Reconceptualizing complex posttraumatic stress disorder: A predictive processing framework for mechanisms and intervention

In this article, we introduce a framework for interpreting Complex Posttraumatic Stress Disorder (C-PTSD) through predictive processing, a neuroscience concept explaining the brain ’ s interpretation and prediction of sensory information. While closely related to PTSD, C-PTSD encompasses additional symptom clusters marked by disturbances in self-organization (DSO), such as negative self-concept, affect dysregulation, and relational difficulties, typically resulting from prolonged traumatic stressors. Our model leverages advances in computational psychiatry and neuroscience, offering a mechanistic explanation for these symptoms by illustrating how prolonged trauma disrupts the brain ’ s predictive processing. Specifically, altered predictive mechanisms contribute to C-PTSD ’ s symptomatology, focusing on DSO: (1) Negative self-concept emerges from maladaptive priors that bias perception towards self-criticism, misaligning expected and actual interoceptive states; (2) Misalignment between predicted and actual interoceptive signals leads to affect dysregulation, with sensitivity to bodily cues; and (3) Relationship challenges arise from skewed social prediction errors, fostering mistrust and withdrawal. This precision-focused approach sheds light on the dynamics underpinning C-PTSD and highlights potential intervention targets aimed at recalibrating the predictive processing system.


Introduction
Complex Posttraumatic Stress Disorder (C-PTSD) is a condition typically precipitated by exposure to prolonged and complex traumatic stressors and maltreatment such as, but not limited to, abuse, neglect or repeated violenceoften occurring during critical developmental periods such as childhood.Throughout this article, we will refer to these experiences collectively as prolonged and complex traumatic stressors.While not classified as a separate diagnosis in the Diagnostic and Statistical Manual of Mental Disorders -Fifth Edition (DSM-5; American Psychiatric Association Association, 2013), the International Classification of Diseases 11th Revision (ICD-11;World Health Organization, 2021) recognizes C-PTSD as a distinct condition, and numerous studies have reliably differentiated between the two disorders (Cloitre et al., 2014;Howard et al., 2021;Hyland et al., 2018;Nickerson et al., 2016;Zerach et al., 2019).It is important to note that while these studies support distinguishing C-PTSD from PTSD, the two conditions are closely related.C-PTSD can be viewed as an important subtype of PTSD, sharing core symptoms but with additional complexities in symptom presentation and etiology.The distinction made in this paper aims to highlight these additional features rather than to suggest a complete separation between the two conditions.The symptom clusters unique to C-PTSD include but extend beyond those associated with Posttraumatic Stress Disorder (re-experiencing, avoidance, hyperarousal, negative alterations in cognition and mood) to include persistent difficulties in affect regulation, negative self-concept and challenges in forming and maintaining relationships (Maercker et al., 2013).Importantly, although several studies highlight the degree of impairment and distress associated with C-PTSD (Brenner et al., 2019;Zerach et al., 2019), its exact etiology and pathogenesis remain partially understood.Current research suggests that C-PTSD arises from the complex interplay of biological, psychological, and environmental factors (Marinova and Maercker, 2015), particularly in the context of prolonged exposure to traumatic events that overwhelm an individual's coping mechanisms (Marinova and Maercker, 2015).However, gaps in our understanding persist, emphasizing the need for further studies to explore how these factors contribute to the onset and progression of C-PTSD, as well as the mechanisms by which repeated trauma can lead to distinct symptomatology compared to PTSD.To address these gaps and provide a solid foundation for our predictive processing model of C-PTSD, it is essential to consider the neurobiological underpinnings of trauma processing and interoception.
While previous predictive processing accounts have provided valuable insights into PTSD, several aspects of C-PTSD remain insufficiently explained.Our model aims to address these gaps.First, previous accounts have not fully captured the distinct symptomatology of C-PTSD as defined in ICD-11, particularly the pervasive disturbances in selforganization including negative self-concept and interpersonal difficulties.Second, existing models have not adequately explained how traumatic experiences alter predictive processing across multiple levels of the cognitive hierarchy in ways specific to C-PTSD, from low-level perceptual processing to high-level beliefs and self-concepts.Third, while some accounts have touched on interoceptive processing, they have not fully elucidated how interoceptive predictive processing contributes to the unique emotional dysregulation and bodily symptoms characteristic of C-PTSD.Finally, previous models have not sufficiently accounted for the mechanisms underlying the persistent and treatmentresistant nature of C-PTSD symptoms over time.Our model addresses these limitations by offering a comprehensive predictive processing framework specifically tailored to C-PTSD, providing a more nuanced explanation of its complex symptomatology and underlying mechanisms.
In this article, we present a new framework for explaining C-PTSD, which may shed light on how exposure to prolonged and complex traumatic stressors may alter perception of the self and, in turn, others and the world among those with C-PTSD.This framework draws on emerging advances in neuroscience and computational psychiatry and may have the potential to inspire new avenues for intervention and research into C-PTSD.We first present the rudimentary principles of predictive processing, a theory suggesting the brain continuously generates and updates predictions about sensory input to minimize the difference between expected and actual signals, before applying it to the hallmark symptoms of C-PTSD (for accounts of PTSD symptomology, i.e. re-experiencing, avoidance, hyperarousal, negative alterations in cognition, and mood; see Kube et al., 2020;Putica et al., 2022aPutica et al., , 2022b)).

Predictive Processing
Predictive processing introduces the internal or embodied model as the brain's method of organizing and interpreting sensory information.It posits that the brain is continually generating, updating, and refining predictions to minimize the mismatch between expected and received sensory inputs, thereby enhancing the precision of its internal representations (see Fig. 1).This ongoing process allows the brain to adapt effectively to new, dynamic, and complex environments (Friston and Kiebel, 2009;Millidge et al., 2021;Seth et al., 2012).Central to this framework is the interaction between prediction errors, priors, and hyperpriors.Priors are essentially the brain's assumptions formed by previous experiences.For example, if one believes a situation to be threatening, this can lead to anticipatory sensory predictions, such as an increased heart rate.These priors function within a hierarchical model at various levels, with hyperpriors at the apex.Hyperpriors are overarching, abstract beliefs that generalize patterns or rules about the world, such as "the world is inherently dangerous."They play a critical role in shaping the brain's predictions, influencing interoception (internal bodily sensations), proprioception (body position and movement), exteroception (external stimuli, like sight and sound) and action by setting expectations that guide the processing of sensory information, from the intensity of light in vision to the sensation of pressure and temperature in touch.This mechanism is crucial for our interaction with the world around us (Clark et al., 2018).
This figure illustrates the hierarchical structure of predictive processing, detailing the flow of predictions from the model to the body's physiological state and how these interact with different levels of prediction errors.High precision prediction errors, indicated by the thick red line, suggest significant deviations from expected physiological responses, while low precision errors, shown by the thin red line, represent less influential deviations.The feedback loop, represented by the solid and dotted back lines, demonstrates the dynamic and ongoing process of updating the predictive model based on the body's actual physiological  state.This conceptual model provides a visual framework for understanding the role of predictive processing in the regulation of emotional and physiological responses following trauma exposure.
Building on this, the concept of active inference suggests that organisms not only modify their internal models in response to prediction errors but also actively engage with their surroundings to align sensory inputs with their expectations (Parr et al., 2019).This active engagement helps to minimize prediction errors through behavior and interaction, further refining the brain's predictive accuracy (Pezzulo et al., 2022;Smith et al., 2021).Precision weighting is another key element within this framework.It allows the brain to assess the reliability of prediction errors, effectively tuning the significance of different sensory inputs.Errors deemed unreliable may be overlooked, while those with higher precision can lead to adjustments in the brain's internal model and its priors (Streng et al., 2022).This selective attention mechanism (see Fig. 2) ensures that the brain focuses on errors that are most likely to refine its predictive model efficiently (Streng et al., 2022).Further, the integration of Bayesian inference highlights the brain's capability to continuously update its hierarchical model based on the balance between prior beliefs and new sensory evidence.This probabilistic approach to prediction adjustment enables the brain to maintain a sophisticated and nuanced understanding of its environment, illustrating the brain's remarkable adaptability and the sophistication of its internal model (Friston and Kiebel, 2009;Seth et al., 2012).
This figure illustrates the cyclical nature of predictive processing, showing the flow from high-level cognitive processes to low-level sensory inputs, and how prediction errors at each level contribute to action and subsequent sensory input.

Novelty of this account
This article introduces a model that integrates current findings from neuroscience and computational psychiatry to provide a new perspective on C-PTSD.It examines how prolonged and complex traumatic stressors, especially during formative years, can alter an individual's perception and contribute to significant issues in self-identity, affect regulation, and interpersonal relationships in C-PTSD.

The predictive processing account of C-PTSD
Building on the core mechanisms of predictive processing, we aim to apply this framework to deepen our understanding of C-PTSD.We will build upon previous computational perspectives on PTSD as presented by Kube et al. (2020), Linson and Friston (2019), Putica et al. (2022aPutica et al. ( , 2022b) ) and Radell et al. (2017), which have primarily focused on PTSD's hallmark symptoms: re-experiencing, avoidance, hyperarousal, and negative alterations in cognition and mood.By extending these discussions, we intend to show how predictive processing can illuminate the processes by which exposure to prolonged and complex traumatic stressors precipitates the development of the hallmark symptoms of C-PTSD.We will start by examining how C-PTSD's etiology, particularly prolonged and complex traumatic stressors, impact one's internal model of self, others, and the world within a predictive processing framework.We will then discuss how this framework provides new insights into the development and maintenance of C-PTSD symptoms.From there, we will propose novel hypotheses for future research and discuss treatment implications arising from our account.

The impact of chronic trauma through predictive processing
Prolonged and complex trauma exposure, especially during childhood, has been linked to various forms of psychopathology throughout one's life (Copeland et al., 2018;McFarlane, 2010;Pfluger et al., 2022).However, the underlying mechanisms, particularly in relation to C-PTSD, remain incompletely understood (Schmitz et al., 2023).From the predictive processing standpoint, it is crucial to examine how prolonged and complex traumatic stressors reshape our internal model of self, others, and the world.This involves looking at how trauma affects the balance and precision of our brain's predictions and the sensory information it uses to make these predictions.
Extensive investigations within neuropsychology have elucidated the profound and multifaceted impact that prolonged and complex traumatic stressors exert on neurobiological systems, leading to significant alterations in brain structure and function that fundamentally modify perceptual and cognitive processing (Assogna et al., 2020;Sala et al., 2020).Bremner (2006) provides compelling evidence that sustained trauma exposure transcends psychological disturbance to induce observable neuroanatomical and neurofunctional alterations.These changes are characterized by neuroplastic adaptations in neural circuitry, including modifications in the volume and connectivity of the hippocampus and prefrontal cortex-regions critically involved in memory, executive function, and affect regulation (Dixon et al., 2017;Jin and Maren, 2015;Preston and Eichenbaum, 2013).Additionally, alterations in the amygdala's structure and function have been implicated in heightened emotional reactivity and impaired fear extinction, further contributing to the complex symptomatology observed in trauma-exposed individuals (Belleau et al., 2020).Marusak et al. (2015) extend these findings by elucidating the cognitive and emotional ramifications of such neurobiological changes.They highlight how trauma-induced alterations in brain networks, particularly those involved in the Salience and Default Mode Networks, disrupt the integration and processing of cognitive and emotional information.This disruption can lead to difficulties in attention, memory, executive functioning, and affect regulation, manifesting as symptoms commonly associated with trauma-related disorders (Marusak et al., 2015).The research collectively underscores the critical need for a neurobiologically informed approach to understanding and treating trauma, emphasizing the importance of interventions that target the underlying neurobiological mechanisms to ameliorate cognitive and emotional disturbances resulting from prolonged trauma exposure.
Within the predictive processing framework, our conscious experience is sculpted by the brain's predictions, which are informed by sensory inputs and past experiences (Friston and Kiebel, 2009).Prolonged and complex trauma exposure, therefore, leads to the establishment of highly probable hypotheses-for example, perceiving situations as unsafe or others as inherently dangerous.These are based on the notable impact of the trauma and the physiological response it triggers.Such trauma-based predictions often get reactivated in later situations, regardless of whether they match current sensory data.This misalignment instils these predictions with excessive precision, allowing them to override actual perceptions and elicit negative emotions tied to present circumstances instead of being correctly attributed to past events.This conceptual framework is underpinned by evidence showing that childhood trauma heightens the risk for various psychopathologies via changes in the Hypothalamic-Pituitary-Adrenal (HPA) axis and alterations in interoceptive processing (Schmitz et al., 2023).Furthermore, individuals with a history of childhood trauma frequently develop generalized fear beliefs towards others and the world (Ready et al., 2015).By integrating the active inference framework with this discussion, we suggest that the priors formed from chronic childhood trauma transform into interoceptive hyper-precise hyperpriors.These are exceptionally strong beliefs that profoundly affect the processing of sensory information.Clark et al. (2018) provide additional support for this model, indicating that continuous, trauma or adversity, such as emotional or physical neglect, promotes an exaggerated perception of uncertainty across situations.This is especially true when others exhibit altruistic or prosocial behavior, which can be misconstrued due to entrenched beliefs in their malevolence.The role of hyperpriors and their precision is pivotal for a comprehensive understanding of C-PTSD symptoms, as we will delve into further.For each of the C-PTSD disturbance in self-organization symptom clusters, we will outline a conceptual A. Putica and J. Agathos framework of its relevance within a predictive processing model of C-PTSD, examine empirical evidence for its role, and outline its consequent clinical implications.

Disturbances in affect regulation
We next aim to outline how a predictive processing framework can account for the hallmark symptoms of C-PTSD according to the ICD-11 (World Health Organization, 2021) along with the conceptual, empirical and clinical evidence for our account of these symptom clusters.We begin with "Severe and pervasive problems in affect regulation" (World Health Organization, 2021).Emotional dysregulation refers to the difficulties in modulating and habituating to intense or unwanted emotional states (Gross, 2015;Gross and Jazaieri, 2014).The former pertains to a restricted ability in employing strategies to alleviate intense affective states leading to challenges in impulse control and execution of goal-directed behavior (Gross, 2015).The latter is characterized by a failure to acknowledge and a reduced perceptual or cognitive recognition of emotional states, manifesting in emotional disengagement or alexithymia (Gross, 2015;Putica et al., 2022aPutica et al., , 2022b;;Sheppes et al., 2015).

Disturbances in affect regulationconceptual
Within the predictive processing paradigm, the impact of prolonged and complex traumatic stressors on the brain's hierarchical modelling system, specifically its hyper-priors and priors, merits close examination.This significantly influences interoceptive awareness and, consequently, affect regulation.The recalibration of these models in response to trauma is particularly profound during critical developmental periods, challenging the brain's foundational expectations of safety and autonomy (see Dehorter and Del Pino, 2020).Hyper-priors, representing the brain's highest-level abstract expectations, adjust to unpredictability by forming beliefs such as "the world is inherently unsafe".This adjustment skews lower-level priors to overpredict threats in benign environments, escalating emotional and physiological responses and creating a self-perpetuating cycle of perceived danger, resulting in persistent states of prediction error.This entrenched adherence to negative hyper-priors, despite disconfirming evidence, keeps the brain in a heightened state of vigilance and anxiety.The ongoing conflict between anticipated and actual experiences not only strains physiological and psychological resources but also fosters a spectrum of psychopathological conditions, including anxiety, depression, and PTSD, which significantly impede an individual's ability to adapt (Paulus et al., 2019;Tucker et al., 2015).
Divergent interoceptive sensitivities observed in individuals with a history of chronic trauma modulate their emotional responses (Schaan et al., 2019;Schmitz et al., 2023).Enhanced sensitivity may lead to the misinterpretation of normal physiological variations as threatening, invoking panic or anxiety.Conversely, reduced sensitivity might cause an estrangement from bodily sensations, complicating the awareness and regulation of emotions (Putica et al., 2022a(Putica et al., , 2022b)).These alterations in interoceptive awareness have profound implications for emotional processing, either by intensifying the misinterpretation of physiological 'noise' as meaningful or by impairing the detection of distress cues (Tan et al., 2023;Ventura-Bort et al., 2021).The effectiveness of affect regulation strategies, as highlighted by research, varies significantly, with proactive strategies like cognitive reappraisal proving more beneficial in mitigating negative emotions and stress responses than suppressive tactics like emotional suppression (Amstadter and Vernon, 2008;Appleton et al., 2014;Gross, 1998).Persistent prediction errors, resulting from the mismatch between expected and actual interoceptive signals, engender continuous uncertainty (Clark et al., 2018;Friston and Kiebel, 2009).These errors may arise from ambiguous afferent signals, a rigid internal model, or a failure to adapt the model in response to contextual shifts.Given the critical function of interoception (for definitions of interoceptive domains, see Table 1) in sustaining homeostasis-the regulation of internal stability in response to external changes-and in affect regulation, it is posited that interoceptive dysfunction is a key mechanistic link between prolonged and complex traumatic stressors and emotional dysregulation (Reinhardt et al., 2020;Schmitz et al., 2023;Zamariola et al., 2019).This perspective underscores the necessity of integrating our understanding of interoceptive processing within predictive processing models to elucidate the complex relationships between trauma, interoception, and emotional dysregulation.

Disturbances in affect regulationempirical
The above-proposed perspective is grounded in empirical evidence that underscores the critical role of interoception in affect processing and regulation.For instance, neuroimaging studies have illuminated the links between specific interoceptive responses and distinct emotional states, demonstrating the biological basis for Damasio's theory of 'somatic markers' (Adolfi et al., 2017;Salamone et al., 2021;Zaki et al., 2012).In Damasio's theory, somatic markers are bodily-based signals that arise in response to emotional stimuli and guide decision-making by associating specific physical states with certain outcomes.Somatic markers, or physiological signals, play a pivotal role in guiding behavior and decision-making, reinforcing the interdependence of interoception and affect regulation.
Further empirical support comes from research identifying a clear connection between childhood trauma and interoceptive awareness.Reinhardt et al. (2020) and Schaan et al. (2019) have shown that traumatic events in childhood, including early life adversity and sexual trauma, are associated with diminished interoceptive accuracy.Conversely, increased interoceptive accuracy has been inversely related to posttraumatic distress, suggesting a link between one's ability to accurately perceive internal bodily signals and their capacity for affect regulation.The association between interoceptive ability and affect regulation is echoed by findings (Brewer et al., 2021;Murphy et al., 2017;Tan et al., 2023) that higher interoceptive accuracy enhances affect regulation capabilities.
Moreover, Schulz et al. (2022) provided intriguing insights into the physiological underpinnings of these observations.Their work with yohimbine, an α2-adrenergic receptor antagonist which activates the sympatho-adreno-medullary axis, revealed that individuals with a history of childhood trauma exhibit a decrease in interoceptive accuracy following administration, in contrast to controls.This suggests that traumatic experiences might induce a physiological readiness for stress

Table 1
Interoceptive dimensions and their relevance to complex PTSD.

Interoceptive Accuracy
The ability to accurately detect internal bodily signals, such as heart rate or hunger.
A person with high interoceptive accuracy can accurately count their heartbeats without feeling their pulse.

Interoceptive Awareness
The level of attention paid to internal bodily sensations, influenced by both accuracy and sensibility.
A therapist helps a patient become more aware of their body's responses to stress, enhancing their interoceptive awareness.Interoceptive Sensibility An individual's self-reported tendency or belief in their attentiveness and sensitivity to internal signals.
A questionnaire reveals that a person believes they are highly attentive to internal signals, like hunger or breathlessness, indicating high interoceptive sensibility.
Note.This table summarizes key terms related to the understanding of interoception in the context of complex PTSD, highlighting the nuances between the accuracy of detecting internal states, the awareness of these states, and the selfreported sensibility towards them.
responses ('fight, flight, or freeze'), which in turn affects the ability to attend to internal bodily signals under conditions of uncertainty, further complicating affect regulation.Lastly, the mediation role of body dissociation, as explored by (Schmitz et al., 2023(Schmitz et al., , 2021)), suggests that atypical interoceptive sensibility-ranging from reduced attention to internal states to overwhelming attentiveness-may bridge the gap between traumatic experiences in childhood and subsequent emotional dysregulation.These studies collectively offer robust empirical support for the predictive processing model's explanation of emotional dysregulation in individuals with C-PTSD, highlighting the significant influence of altered interoceptive processing shaped by early traumatic experiences.
Neuroimaging studies have provided valuable insights into the neural underpinnings of interoceptive processing and emotion regulation in trauma-related disorders, particularly relevant to disturbances in affect regulation.Research consistently shows altered connectivity between the insula, amygdala, and prefrontal regions in individuals with PTSD (Hinojosa et al., 2024).Specifically, PTSD is associated with hyperactivation of the amygdala and insula, coupled with hypoactivation of prefrontal regions during emotion processing and regulation tasks.This altered connectivity pattern is thought to contribute to heightened threat sensitivity and difficulties in emotion regulation characteristic of PTSD.Building on these findings, Lanius et al. (2015) proposed a neural model of PTSD that highlights disruptions in large-scale brain networks related to affect regulation.A key component of this model is the Salience Network, which encompasses the insula and amygdala.In PTSD, this network shows heightened activity and connectivity, potentially leading to an overly sensitive threat detection system.This hypervigilance may contribute to the persistent re-experiencing and hyperarousal symptoms observed in PTSD, which are closely tied to affect dysregulation.While most neuroimaging studies have focused on PTSD, emerging research suggests that C-PTSD may have both overlapping and distinct neural correlates related to affect regulation.For instance, Bryant et al. (2021) found that individuals with C-PTSD, compared to those with PTSD, showed greater bilateral insula and right amygdala activation during conscious processing of threat stimuli.This heightened activation may underlie the more pervasive emotional dysregulation characteristic of C-PTSD.However, both groups showed similar patterns of reduced dorsolateral prefrontal cortex activation, suggesting some shared neural mechanisms in top-down emotional control.These findings highlight the need for more research, specifically examining the neural correlates of affect dysregulation in C-PTSD.Future studies should aim to disentangle the shared and distinct neural mechanisms underlying affect regulation difficulties in PTSD and C-PTSD, which could inform more targeted treatment approaches for each condition.

Disturbances in affect regulationclinical
The emerging clinical evidence linking interoception to adaptive affect regulation and self-concept disturbances in individuals with C-PTSD offers support for our predictive processing account.Specifically, the work of Schmitz et al. (2021) highlights the correlation between interoceptive sensibility and affect dysregulation, a connection that is notably pronounced in fibromyalgia-a condition prevalent among survivors of chronic trauma (Combas et al., 2022).This burgeoning area of research is foundational to the predictive processing framework, positing that disruptions in the accurate perception and interpretation of internal bodily signals are instrumental in the emergence and perpetuation of altered self-concept and compromised affect regulation capabilities within this population.Elucidating the mechanisms through which impaired interoception contributes to C-PTSD's complex symptomatology further substantiates our account.For instance, studies have shown that individuals with C-PTSD often exhibit a heightened or diminished awareness of internal bodily sensations (Schaan et al., 2019;Schmitz et al., 2023), such as heart rate or respiratory changes, which in turn affects their ability to regulate emotional responses to stress or trauma cues appropriately (Tan et al., 2023).This dysregulation manifests in a range of psychopathologies (for a review, see Sheppes et al., 2015).
The clinical relevance of these findings is further supported by the success of therapeutic interventions targeting interoceptive awareness.Techniques such as Mindfulness-Based Stress Reduction (MBSR; Kabat-Zinn, 2003) which has been found to be effective in addressing C-PTSD symptomology (Dumarkaite et al., 2022) incorporate elements designed to enhance interoceptive tolerance and accuracy.By doing so, they facilitate a more nuanced understanding and integration of bodily sensations with corresponding emotional states.This process not only aids in the alleviation of posttraumatic symptomatology but also contributes to the reconstruction of a more coherent and positive self-concept among individuals with C-PTSD (Putica et al., 2024).For example, mindfulness practices focusing on body scanning and conscious breathing can help individuals re-engage with their bodily sensations in a non-judgmental and exploratory manner, countering the tendency to dissociate from or misinterpret these cues (Kang et al., 2022).The clinical evidence thus underscores the profound impact of interoception on the emotional and psychological well-being of individuals with C-PTSD.By advancing our understanding of the interplay between interoceptive awareness and affect regulation within the predictive processing framework, these insights pave the way for more targeted and effective interventions.

Negative self-concept
In the context of C-PTSD, negative self-concept is characterized by maladaptive cognitive processes and rigid negative beliefs about one's self-identity and self-worth.Individuals with C-PTSD exhibit a selfperception that is marked by feelings of defeat (Ebert and Dyck, 2004) or intrinsic worthlessness (Cloitre et al., 2013).This self-assessment is frequently accompanied by enduring affective states of shame, guilt or perceived failure, which are directly attributable to the individual's experience of prolonged and complex traumata exposure.The characteristics of a negative self-concept manifest in several distinct, yet interrelated dimensions.These individuals often experience low self-esteem, frequently attributing their worthlessness to an inherent flaw within themselves, which they believe to be 'the reason' for them experiencing the trauma (Banz et al., 2022).These feelings of low self-esteem are compounded by persistent feelings of shame and guilt (Banz et al., 2022).Moreover, those with C-PTSD often experience a chronic sense of failure, which permeates various facets of their life and reinforces one's negative self-concept (Banz et al., 2022).As a result of the interplay of these cognitions, individuals with C-PTSD perceive themselves as fundamentally different from othersa perception that exacerbates social isolation and withdrawal impeding one's access to corrective experiences (Fox et al., 2022).

Negative self-concept -conceptual
Within the predictive processing framework, interoception's pivotal role in crafting and perpetuating maladaptive expectations becomes evident, culminating in a persistent negative self-concept among individuals afflicted with C-PTSD.Chronic exposure to trauma, particularly forms such as abuse or neglect encountered in early developmental stages, not only molds anticipatory models for social interactions, engendering a profound expectation of rejection or criticism (for example see Clark et al., 2018) but also significantly impacts the processing of interoceptive signals during these interactions.For example, an elevated heart rate might be interpreted as a sign of anxiety or hypervigilance, leading individuals to scrutinize and misinterpret interactions as containing cues of rejection or criticism, even when such cues are non-threatening or neutral.This mechanism perpetuates a cycle of alienation, where high-level generative models and priors, forecasting constant threat or social danger, shape the interpretation of social cues and bodily signals, thus reinforcing these negative expectations.
The maladaptive cycle characteristic of C-PTSD involves a nuanced interaction between active and interoceptive inference, whereby both external and internal signals are filtered through highly specific hyperpriors of unworthiness or inevitable rejection.These hyper-priors skew perception, causing individuals to detect rejection or criticism in otherwise neutral or ambiguous social exchanges, while also misinterpreting physiological responses-such as an increased heart rate or muscle tension-as signs of negative feedback.This misinterpretation not only consolidates a negative self-concept but also triggers an amplified stress response, further embedding the maladaptive hyperpriors associated with perceived threats or social dangers.
In contrast, positive social interactions, which could counteract the negative self-concept, are de-emphasized, diminishing their capacity to amend or refresh the internal, embodied working model of self.Nevertheless, experiences or interoceptive signals that validate existing priors are given heightened precision (reliability), perpetuating a cycle of negative self-evaluation.This interplay of emotion and perception in C-PTSD deeply influences enduring feelings of shame and guilt.These emotions are closely tied to individuals' self-perception in social contexts; shame emerges from the misinterpretation of social interactions, whereas guilt arises from a skewed causal interpretation, where negative social outcomes, whether actual or perceived, are wrongly attributed to personal flaws or inadequacies.

Negative self-conceptempirical
Empirical research offers robust support for our conceptual account of negative self-concept in C-PTSD.Dorahy et al. (2013) provide initial evidence by demonstrating that individuals with clinical levels of dissociation-marked by a profound disconnection between the self, cognition, and bodily sensations-exhibit greater C-PTSD symptomology.Furthermore, these individuals display increased levels of both state and trait guilt and shame, coupled with a tendency toward social withdrawal and an obsessive preoccupation with social interactions (Brewin, 2020;Kvedaraite et al., 2022;Palic et al., 2016).These findings highlight the critical interplay between interoception and the perception of self in relation to others.Expanding on these findings, the role of Theory of Mind (ToM)-the ability to attribute mental states to oneself and others to infer their behavioural intentions-was examined in the context of childhood trauma survivors (Shah et al., 2017).Shah et al. (2017) found a positive correlation between interoceptive accuracy and ToM abilities.This indicates that while interoception is not essential for the basic representation of mental states, it significantly enhances the accuracy of these representations.This notion is supported by research linking visceral sensitivity to empathy (Fukushima et al., 2011;Grynberg and Pollatos, 2015), underscoring the importance of interoception in understanding and empathizing with the mental states of others.
On a neural level, individuals with C-PTSD show significant alterations in brain activation and connectivity, particularly within the Default Mode Network (DMN), which are highly relevant to the negative self-concept characteristic of the disorder.The DMN is a group of brain regions including the ventral and dorsal medial prefrontal cortex, inferior parietal cortex, lateral temporal cortex, posterior cingulate, and parahippocampal regions (Buckner et al., 2008).This network is crucial for self-referential processing, including reflecting on oneself, ruminating about the past, and envisioning the future (Benjamin et al., 2010) -all processes that can contribute to the formation and maintenance of self-concept.Recent studies have revealed significant C-PTSD-related alterations in DMN function (Dai et al., 2021;Daniels et al., 2011;Lanius et al., 2011;Schlumpf et al., 2021).These alterations include reduced connectivity within the DMN, particularly between the posterior cingulate cortex and the medial prefrontal cortex.Such disruptions may underlie the fragmented sense of self and identity disturbances often reported by individuals with C-PTSD, contributing to the development and persistence of a negative self-concept.Moreover, altered connectivity between the DMN and the Salience Network has been observed in C-PTSD (Viard et al., 2019).This disrupted inter-network communication may indicate impaired integration between interoceptive processing and self-referential thinking.Integration of interoceptive signals with self-referential thinking is crucial for maintaining a coherent sense of self.Disruption in this integration can lead to difficulties in experiencing primordial feelings and forming knowledge for cognition, which may affect emotional experience, social cognition, and regulatory behavior (Dinulescu et al., 2021;Holly, 2020;Seth, 2013).These difficulties can further reinforce negative self-perceptions and beliefs.
The accumulation of empirical evidence underpins the relationship between interoception, self-perception, and social cognition in C-PTSD.From the dissociative experiences linked to C-PTSD symptomology to the nuanced role of interoceptive accuracy in ToM and the alterations in the DMN, these studies collectively affirm the complexity of negative self-concept in C-PTSD.This body of work not only validates the conceptual framework by outlining how empirical evidence directly connects alterations in interoceptive processing and social cognition with the development and perpetuation of a negative self-concept in C-PTSD, but also emphasizes the need for further investigation into the mechanisms that underlie these relationships.

Negative self-conceptclinical
Recent research exploring the origins and persistence of Social Anxiety Disorder (SAD), a condition marked by extreme fear and avoidance of social settings due to fear of judgment (American Psychiatric Association and Association, 2013) and its link to childhood trauma, offers clinical support for our understanding of C-PTSD through the lens of predictive processing.Kuo et al. (2011) discovered that individuals with SAD experienced more childhood emotional abuse and neglect compared to those without SAD.This connection between early trauma and the development of SAD corroborates our theory that such trauma leads to the creation of maladaptive predictive models about oneself.These models, expecting negative social outcomes as a result of personal failings, influence how individuals perceive and emotionally process their experiences, perpetuating feelings of anxiety and alienation.
Building upon this, Lochner et al. (2010) noted the widespread occurrence of childhood trauma in individuals with both SAD and panic disorder.Given that panic disorder is essentially a disorder of interoception, characterized by recurrent panic attacks and a heightened sensitivity to internal bodily sensations, this finding further emphasizes the relationship between social cognition, entrenched beliefs about negative evaluations, and the incorrect interpretation of bodily signals in those who have suffered chronic trauma.Lucero et al. (2022) extended these insights by showing that the link between mood disorders and childhood trauma is mediated by fears of social evaluation, supporting Clark et al. (2018)'s hypothesis that mood disorders stem from the misinterpretation of bodily signals.This misinterpretation, resulting from a mis calibrated neuromodulation threshold due to trauma/adversity, leads to altered body signal regulation and chronic negative mood states, perpetuated by the anticipation of negative outcomes and a heightened sensitivity to bodily cues.
These inflexible beliefs about negative social evaluations and the misinterpretation of bodily signals predispose individuals to anticipate negative social interactions with a high degree of certainty, potentially impeding therapeutic progress due to concerns over negative evaluation by therapists or peers.This discrepancy in treatment outcomes underscores the complex interplay between anxiety disorders and treatment efficacy, highlighting the need for tailored approaches that address these deeply held beliefs.These studies collectively offer strong clinical support for our predictive processing framework in understanding C-PTSD, demonstrating how maladaptive predictive models, deeply ingrained through trauma, forecast adverse social outcomes.These models are maintained through both active engagement with the environment and the interpretation of internal bodily cues, underscoring the complexity of C-PTSD and the challenges it presents for treatment.

Difficulties in sustaining relationships
The Difficulties in Sustaining Relationships symptom cluster delineates the pronounced disturbances in interpersonal dynamics endemic to individuals diagnosed with C-PTSD (World Health Organization, 2021).Such individuals exhibit systemic fragility in trust paradigms or perceive heightened vulnerability, often as a sequela of betrayal or harm inflicted by individuals within their close or trusted circles (World Health Organization, 2021).Manifestations of fear and mistrust towards others materialize in multifaceted ways that exacerbate relational complexities (Ford and Courtois, 2021).For example, these individuals may encounter significant barriers to engaging in emotional disclosures or demonstrating vulnerability, inhibited by apprehensions of potential harm or misinterpretation.Furthermore, there is a tendency towards the formation of unstable relational dynamics, marked by pronounced emotional volatility (Ford and Courtois, 2021).This is perpetuated by the individual's entrenched negative self-perception and a pervasive skepticism towards others' intentions and behaviors (Kampling et al., 2022).

Difficulties in sustaining relationshipsconceptual
In the context of our predictive processing framework, we delineate the nuanced processes underpinning the interpersonal challenges manifest in individuals with C-PTSD, with a particular focus on the formation and perpetuation of trust and intimacy deficits.These challenges are rooted in the individual's traumatic experiences, frequently characterized by their interpersonal nature (Dorahy et al., 2013;Giourou et al., 2018;Palic et al., 2016), leading to a predisposition towards interpreting ambiguous social cues as indications of potential deceit or harm (Bertó et al., 2023).This predisposition is anchored in entrenched hyperpriors, which are essentially maladaptive predictive models that anticipate adverse social interactions.Notably, these hyperpriors are resistant to modification, even in the face of disconfirming experiences, leading to a persistent guarded stance in social contexts (Clark et al., 2018).This state necessitates an ongoing regulatory effort to minimize trust-related prediction errors, consequently fostering social isolation and perpetuating misunderstandings (Clark et al., 2018).For instance, consider the dynamics of a social interaction where a benign comment is made.An individual with C-PTSD, through the lens of their maladaptive hyperpriors, may interpret this as covert criticism or rejection.This is a clear example of how a Bayesian brain might fail to update its priors in the face of new, non-confirmatory evidence, thereby reinforcing a state of hyper-vigilance and withdrawal in social settings.Moreover, the concept of active inference becomes crucial in understanding the tendency of these individuals to gravitate towards relationships that validate their negative expectations.Active inference, a fundamental mechanism in predictive processing, describes how an agent seeks to minimize the discrepancy between its predictions and the sensory evidence it receives.In the context of C-PTSD, this means engaging in social interactions that are congruent with their established hyperpriors, thus reducing prediction error.Engaging with individuals who exhibit predictable, albeit negative, behaviors allows for a reduction in the cognitive dissonance experienced by the individual with C-PTSD, further entrenching their hyper-priors related to mistrust and social rejection.The maladaptive interoceptive inference process, another facet of predictive processing, elucidates the disjunction between internal state perception and actual social interactions.An exemplar scenario could involve an individual with C-PTSD interpreting a delayed response to a message as a profound indication of disinterest or abandonment.This interpretation triggers a disproportionate internal distress response, reflective of a heightened interoceptive prediction error.Such instances exemplify the predictive processing framework's concept of the brain as a Bayesian inference machine, where the expectation of a negative outcome leads to an overinterpretation of innocuous stimuli as threatening or rejecting, perpetuating a state of internal distress and maladaptive social navigation.These insights underscore the critical misalignment between the internal predictive models, heavily influenced by past traumas, and the realities of present social environments in individuals with C-PTSD.

Difficulties in sustaining relationshipsempirical
Empirical studies reveal a multifaceted relationship among chronic trauma, difficulties in forming and maintaining relationships, and underlying neurobiological mechanisms, all of which resonate with the principles of our predictive processing framework.Research indicates that individuals with a history of chronic trauma often hold entrenched beliefs of mistrust and suspicion towards others (Ebert and Dyck, 2004;Jepsen et al., 2013;Karatzias et al., 2016).These beliefs foster persistent doubts about the goodwill of others, adversely affecting the development and maintenance of healthy interpersonal relationships (Briere and Jordan, 2009;Pearlman and Courtois, 2005).For instance, research has documented that children subjected to rejection or abuse as a response to their emotional expressions tend to suppress their emotional needs over time, a behavior that becomes generalized across various relationships.This contradiction, where the caregiver represents both a source of threat and solace, paradoxically fosters a sense of alienation and isolation, a pattern that often continues into adulthood (Amos et al., 2015;Van Nieuwenhove and Meganck, 2019;Zilberstein and Messer, 2010).
Further supporting our theoretical model, the role of the insula in mediating the intersection between interoceptive awareness and social decision-making has been highlighted.The insula has been implicated in how physical sensations influence trust-related behaviors, as evidenced by studies employing temperature manipulation and trust games (Kang et al., 2011).Additionally, individuals with insular damage display atypical trust behaviors (Belfi et al., 2015), suggesting that the insula's function transcends the mere integration of sensory information to include the essential processing of interoceptive data.This link between interoceptive awareness and social cognition positions the insula as a pivotal bridge connecting our physical self-perception with our social interactions.The integration of interoceptive signals and social cognition suggests that our internal bodily states significantly influence our social interactions and trust decisions.Collectively, this body of evidence supports our predictive processing framework for understanding relationship difficulties in individuals with C-PTSD.It demonstrates that such individuals may anticipate danger or malevolence in others or may seek relationships that affirm their negative expectations to minimize the 'surprise' or prediction error.This evidence enriches our understanding of the predictive processing framework by illustrating how chronic trauma can shape neurobiological processes and social cognition, leading to persistent difficulties in interpersonal relationships.

Difficulties in sustaining relationshipsclinical
The therapeutic relationship emerges as pivotal clinical evidence supporting our predictive processing framework for understanding the interpersonal challenges faced by individuals with C-PTSD.Notably, countertransference reactions within the therapeutic setting highlight this evidence.These reactions occur when a patient's historical traumatic interpersonal experiences and their associated hyper-priors-expectations that undermine their sense of safety in relationships-are re-enacted in therapy.For instance, therapists may feel resentment or disapproval toward patients who appear avoidant or display irritability/aggression, behaviors developed as protective mechanisms against past betrayals.Such reactions from therapists can unintentionally reinforce the patients' deeply ingrained hyper-priors, Individuals with complex PTSD will show a tendency towards overregulation of affective states when presented with interoceptive cues, contributing to emotion numbing or alexithymia, more so than controls The Trauma Script Emotion Discordance Task: Participants are exposed to personalized trauma scripts that recount their index traumatic experience, narrated with sensory details to evoke emotional and physiological responses.The experiment measures emotion response concordance, which refers to the alignment between subjective emotional experiences and physiological responses, such as skin conductance (Galvanic Skin Response, GSR) and Total Mood Disturbance (TMD).Concordance between these responses is considered essential for effective emotional processing and adaptation to stressors.The brain's predictive models fail to undergo timely or precise updates with interoceptive inputs Individuals with complex PTSD exhibit inadequate regulation of emotional responses to bodily sensations until these sensations intensify to a point of overwhelming distress.
Emotion Induction with Interoceptive Manipulation: Emotions are induced through standard methods (e.g., viewing emotional pictures, recalling emotional memories) while simultaneously manipulating interoceptive cues (e.g., through breathing exercises that mimic physiological responses to stress or anxiety).The intensity of interoceptive manipulation is gradually increased to examine the participants' capacity for affect regulation and the threshold at which regulation fails.

Negative Self Concept
Biased predictions reinforce threat anticipation and arousal leading to a recursive feedback loop escalating into negative secondary emotions In individuals with complex PTSD, a reciprocal relationship between threat anticipation and psychophysiological arousal is proposed, whereby each element reinforces the other.This cyclical interaction is hypothesized to trigger an affective spiral, manifesting as secondary emotions like shame and guilt, thus exacerbating complex PTSD symptoms Ecological Momentary Assessment (EMA): EMA involves collecting data in real-time using portable devices as participants go about their daily lives.

Difficulties in sustaining relationships
Low precision afforded to pro social prediction errors Individuals with complex PTSD will exhibit slower and less accurate behavioural adaptations to social prediction errors compared to controls Behavioural Adaptation to Prediction Errors: This involves tasks where participants must adjust their behavior based on the mismatch between expected and received social feedback.By measuring the rate and manner of adaptation, it could be possible to assess how altered predictive processing mechanisms impact social interaction strategies in CPTSD.Inflexibility in social interactions due to high precision hyper-priors anticipating negative outcomes Individuals with complex PTSD will show distinct neural and behavioural responses to social prediction errors, compared to control participants, indicating altered flexibility and accuracy in their social predictive processing processes.Specifically, it is hypothesized that those with complex PTSD will demonstrate increased neural activity in areas Social Prediction Error Tasks: These tasks involve situations where the expected social outcome does not match the actual outcome, creating a prediction error.By measuring neural and behavioural responses to social prediction errors, researchers can assess the flexibility and accuracy of social predictive processing in individuals with CPTSD.
(continued on next page) A. Putica and J. Agathos sustaining a cycle of mistrust and defensive behavior (Dalenberg, 2004;Pressley and Spinazzola, 2015;Zorzella et al., 2014).Additionally, therapeutic attempts characterized by acceptance and compassion may be undermined by the patient's prediction error being assigned low precision.This discrepancy illustrates the challenge in altering expectations based on past negative interactions, perpetuating difficulties in establishing therapeutic rapport with individuals diagnosed with C-PTSD.The crucial role of the therapeutic alliance in addressing C-PTSD is underscored by the development of multi-phased interventions designed to build upon a foundation of interpersonal safety.Such interventions aim to facilitate the processing of traumatic experiences and enhance functioning, recognizing the importance of overcoming hyper-priors of interpersonal mistrust through the establishment of a secure therapeutic relationship.Evidence-based treatments and models that priorities this approach include the Skills Training in Affective and Interpersonal Regulation (STAIR; Cloitre et al., 2010Cloitre et al., , 2020) ) Stepped Model of C-PTSD treatment, alongside other therapeutic frameworks emphasizing the significance of a robust therapeutic alliance in promoting recovery and functional improvement in C-PTSD patients (Cloitre et al., 2020(Cloitre et al., , 2010;;Cloitre and Schmidt, 2022;Jackson et al., 2019;Pearlman and Courtois, 2005).

Limitations and future research
In this article, we endeavor to present a predictive processing framework to dissect the core symptoms of C-PTSD, aiming to shed light on its etiology and pathogenesis.However, we recognize certain limitations within our exposition.Notably, we concede that the mechanisms delineated may not function in isolation but might interact or co-occur with other mechanisms, contributing to a complex, recursive interplay of symptomatology.For instance, emotion dysregulation can impair the maintenance of intimate relationships through perceived rejection or criticism, further reinforcing a negative self-perception as being "defective" or "distinct from others," thereby perpetuating the cycle.Despite this, we consider these mechanisms as foundational elements that, when combined, offer a personalized, predictive processing interpretation of C-PTSD.This approach aims to clarify the disorder's heterogeneous nature and identify specific intervention targets.Moreover, we acknowledge that the application of predictive processing models extends beyond C-PTSD, suggesting a potential unified framework for understanding variabilities in psychiatric conditions.Our discussion does not distinguish between types of trauma, the severity of adversity, or developmental periods of exposure, primarily as they are not necessary conditions for C-PTSD.Previous literature (Kube et al., 2020;Linson and Friston, 2019;Putica et al., 2022) supports the predictive processing framework's applicability across different trauma types, arguing that changes may only pertain to nuances in priors, with the interaction between self and world views remaining largely consistent.Additionally, our account does not directly address hallmark PTSD symptoms such as re-experiencing, hyperarousal, avoidance, and negative alterations in cognition and mood (American Psychiatric Association and Association, 2013).However, this omission is intentional, as detailed explorations of these symptom clusters have been undertaken in prior works (Kube et al., 2020;Linson and Friston, 2019;Putica et al., 2022), and our discussion is intended to complement these analyses.Crucially, a predictive processing framework does not simplify C-PTSD to a singular cause, mechanism, or treatment approach.Instead, it proposes a comprehensive and integrated framework that can enhance personalized treatment by augmenting existing methods.Given the theoretical nature of our proposal, further empirical research is imperative to validate our model and uncover its clinical implications.We outline potential future research directions (Table 2) and propose specific hypotheses derived from our predictive processing account, alongside experimental validation suggestions, to advance the understanding of C-PTSD's mechanisms.
Firstly, to test our mechanisms explaining disturbances in affect dysregulation could be tested by exploring how elements of interoceptive processing (for example sensibility via the MAIA (Multidimensional Assessment of Interoceptive Awareness; Mehling et al., 2012) or accuracy (Heartbeat detection task; Schandry, 1981) impacts one's ability to adaptively regulate emotion (i.e.monitor and change emotion regulation strategy choice to engage in goal-directed behavior); update beliefs/behavior.Secondly, to test the hypothesis outlined by our account regarding the underpinning mechanisms of a negative self-concept could be examined via numerous paradigms examining belief updating and belief perseveration and its impact on secondary emotional states such as shame and guilt and the role of interoception on social cognition and mentalizing.Finally, experimental protocols examining social behavior beliefs under conditions of uncertainty may be used to examine our hypotheses pertaining to difficulties in close relationships among those with C-PTSD.

Conclusion
In conclusion, our article offers a pioneering perspective on Complex Posttraumatic Stress Disorder (C-PTSD) by integrating the principles of predictive processing with contemporary insights from neuroscience and computational psychiatry.We propose a novel framework that not only deepens our understanding of the etiology and symptomatology of C-PTSD but also opens new avenues for therapeutic interventions.By elucidating the mechanisms through which prolonged trauma reshapes perception, self-concept, and interpersonal relations, we highlight the critical role of predictive processing in the maintenance and manifestation of C-PTSD symptoms.Our account emphasizes the importance of considering the intricate interplay between cognitive processes and affect regulation in the treatment and management of C-PTSD.We believe that this integrative approach not only offers a comprehensive understanding of the disorder but also underscores the potential for developing more effective, personalized treatment strategies.Future research should aim to empirically validate the proposed mechanisms and explore their clinical implications, paving the way for innovative interventions that can better address the complex needs of individuals with C-PTSD.associated with threat detection and affect regulation, such as the amygdala and prefrontal cortex, in response to unexpected social outcomes.Ambiguity/uncertainty in social interactions linked to priors of benevolence and negative affect Individuals with C-PTSD will have a different neural reaction indicative of anxiety/fear to unexpected stimuli in their environment, specifically when it comes to social cues Mismatch Negativity (MMN) Experiments: MMN is an event-related potential (ERP) component elicited by deviant stimuli in a sequence of regular stimuli.In the context of CPTSD, MMN experiments could investigate whether individuals show altered neural responses to unexpected social cues or tones, indicating differences in predictive processing.

Fig. 2 .
Fig. 2. The predictive processing process in facial recognition and emotional processing.
It can capture instances of threat anticipation, psychophysiological arousal, and emotional responses, offering insights into the naturalistic dynamics of the hypothesized cyclical interaction.Influence of Hyperpriors on Social Cognition Hyperpriors anticipating threat/ malevolence from others significantly impairs social cognition in individuals with C-PTSD Eye-tracking in Social Interaction Tasks: By monitoring eye movements, this task can reveal how individuals with C-PTSD focus on and interpret social cues compared to those without such hyperpriors.The underlying premise is that individuals with C-PTSD, due to their altered anticipation of threat, might exhibit abnormal eye movement patterns, such as an increased focus on potentially threatening aspects of faces (e.g., angry expressions) or a tendency to avoid eye contact altogether.Disrupted Integration of Interoceptive Signals and Social Cognition Impaired interoceptive awareness significantly impedes Theory of Mind capabilities in individuals with complex post-traumatic stress disorder C-PTSD Reading the Mind in the Eyes Test (RMET): This test requires participants to identify emotions and mental states from photographs focusing on the eye region of faces.By comparing RMET scores among individuals with C-PTSD to controls, alongside evaluating their interoceptive awareness, researchers assess the impact of impaired interoceptive awareness on Theory of Mind capabilities.Lower RMET scores in C-PTSD individuals with diminished interoceptive awareness would indicate a correlation between interoception and the ability to accurately infer others' mental states, supporting the hypothesis.

Table 2
Proposed future research directions.