Examining the continuum of psychosis: Frequency and characteristics of psychotic-like symptoms in relatives and non-relatives of patients with schizophrenia

doi:10.1016/j.schres.2016.07.015

Schizophrenia Research

Volume 178, Issues 1–3, December 2016, Pages 6-11

https://doi.org/10.1016/j.schres.2016.07.015 Get rights and content

Abstract

Background

A key finding underlying the continuum of psychosis concept is the presence of psychotic-like experiences (PLEs) in healthy subjects. However, it remains uncertain to what extent these experiences are related to the genetic risk for schizophrenia and how far they actually resemble attenuated forms of psychotic symptoms.

Methods

Forty-nine adults with no history of mental illness in first-degree relatives and 59 siblings of patients with schizophrenia were rated on the psychosis section of the Computerized Diagnostic Interview Schedule IV (C DIS-IV) and the Rust Inventory of Schizotypal Cognitions (RISC). Those who rated positive on the CDIS-IV were re-interviewed using the lifetime version of the Present State Examination 9th edition (PSE-9) and the Structured interview for Schizotypy (SIS).

Results

Seventeen (34.69%) of the non-relatives and 22 (37.29%) of the relatives responded positively to one or more of the psychosis questions on the DIS. This difference was not significant. RISC scores were also similar between the groups. At follow-up interview with the PSE-9, 13/40 PLEs (32.50%) in the non-relatives were classified as possible or probable psychotic symptoms compared to 11/46 (23.91%) in the relatives. Using liberal symptom thresholds, 5 of those who attended the follow-up interview (2 non-relatives and 3 relatives) met SIS criteria for schizotypal personality disorder.

Conclusions

Rates of PLEs, however considered, do not differ substantially between relatives and non-relatives of patients with schizophrenia. Only a minority of PLEs picked up by screening interviews resemble attenuated forms of psychotic symptoms.

Section snippets

Subjects

The sample consisted of 108 healthy adults, 49 with no history of major mental illness in first-degree relatives and 59 who were the siblings of patients with schizophrenia. The non-relatives were recruited via poster and web-based advertisement in the hospital and local community, plus word-of-mouth requests from staff in the research unit. They were excluded if they reported having a first-degree relative with an established diagnosis of major mental illness, or who had symptoms suggestive of

Results

Demographic characteristics of the two groups are shown in Table 2. The relatives and non-relatives were well matched for age and sex, and also did not differ on TAP-estimated IQ. However, the relatives had significantly lower SESs than the non-relatives.

Discussion

Although the continuum of psychosis is strictly speaking a ‘phenotypic’ construct, i.e. it refers to a continuity between normal experiences and psychotic symptoms, in practice a link to underlying risk factors, especially genetic susceptibility, is almost always assumed (Johns and van Os, 2001, van Os et al., 2000). On these grounds, a higher prevalence of PLEs would be expected in the relatives of schizophrenic patients than in the general population. This prediction was not supported in the

Role of the funding source

This work was supported by the Catalonian Government (2014-SGR-1573 to E.P.-C), and the Instituto de Salud Carlos III-Subdirección General de Evaluación y Fomento de la Investigación and the European Regional Development Fund (FEDER): Miguel Servet research contracts (CPII13/00018 to R.S. and CP10/00596 to E.P.-C.), Rio Hortega research contract (CM1400048 to A.R.) and Research Projects (PI14/01148 to E.P.-C., PI14/01151 to R.S., PI14/01691 to P.M. and PI12/00,686 to S·S). These funding

Conflict of interest statement

All authors state that they have no financial interests to declare.

Author contributions

Peter McKenna and Edith Pomarol-Clotet designed the study. Carmen Sarrí, Ramon Landin-Romero, Ana Romaguera, Eva Álvarez-Moya and Ariadna Compte recruited subjects for the study. Ramon Landin-Romero, Ana Romaguera, Eva Álvarez-Moya, Candibel Aguirre, Ariadna Compte and Clara Bosque tested the subjects. Salvador Sarró, Raymond Salvador, Eva Álvarez-Moya, Ana Romaguera, Peter McKenna, Ramon Landin-Romero and Edith Pomarol-Clotet carried out the data analysis. Peter McKenna and Ramon Landin-Romero

Acknowledgements

PJM is supported by CIBERSAM, Spain. We thank the patients, their relatives and volunteers for their indispensable contribution.

References (32)

T. Del Ser et al.
Estimation of premorbid intelligence in Spanish people with the word accentuation test and its application to the diagnosis of dementia
Brain Cogn.
(1997)
J.J. Gomar et al.
Validation of the word accentuation test (TAP) as a means of estimating premorbid IQ in Spanish speakers
Schizophr. Res.
(2011)
L.C. Johns et al.
The continuity of psychotic experiences in the general population
Clin. Psychol. Rev.
(2001)
E.C. Johnstone et al.
Edinburgh high risk study–findings after four years: demographic, attainment and psychopathological issues
Schizophr. Res.
(2000)
S. Ochoa et al.
What is the relative importance of self reported psychotic symptoms in epidemiological studies? Results from the ESEMeD–Catalonia study
Schizophr. Res.
(2008)
S.I. Tarbox et al.
A multivariate perspective on schizotypy and familial association with schizophrenia: a review
Clin. Psychol. Rev.
(2011)
J. van Os et al.
Strauss (1969) revisited: a psychosis continuum in the general population?
Schizophr. Res.
(2000)
D. Corstens et al.
Emerging perspectives from the hearing voices movement: implications for research and practice
Schizophr. Bull.
(2014)
A.S. David
Why we need more debate on whether psychotic symptoms lie on a continuum with normality
Psychol. Med.
(2010)
M.B. First et al.
The Structured Clinical Interview for DSM-IV Axis I Disorders (Research Version)
(2002)

E.M. Goldberg et al.

Schizophrenia and social class

Br. J. Psychiatry

(1963)

A.B. Hollingshead et al.

Social class and mental illness: a community study. 1958

Am. J. Public Health

(2007)

S. Jastak et al.

The Wide Range Achievement Test–Revised Administration Manual

(1984)

E.C. Johnstone et al.

Predicting schizophrenia: findings from the Edinburgh high-risk study

Br. J. Psychiatry

(2005)

K.S. Kendler

Diagnostic approaches to schizotypal personality disorder: a historical perspective

Schizophr. Bull.

(1985)

K.S. Kendler et al.

The structured interview for schizotypy (SIS): a preliminary report

Schizophr. Bull.

(1989)

Cited by (10)

Schizophrenia
2022, The Lancet
Citation Excerpt :
Studies have yet to show that psychotic-like experiences follow a half-normal distribution in the population (van Os and colleagues’ preferred model), and according to some the continuum view is “at best premature and at worst wrong scientifically”.176 The 5–7% prevalence figure might also be an overestimate: most studies to date have not explored the nature of the experiences their participants reported, and the few that have done so have reported a substantial rate of false positives—real persecution (eg, workplace harassment), culturally accepted beliefs (eg, in witchcraft), and the so-called hallucinations of widowhood, among other things.177–179 However, if nothing else this research initiative has placed beyond doubt the fact that otherwise healthy individuals can sometimes have quite arresting unusual beliefs and experiences, with one example being a former director of WHO's Division of Mental Health (panel 3).180
Schizophrenia, characterised by psychotic symptoms and in many cases social and occupational decline, remains an aetiological and therapeutic challenge. Contrary to popular belief, the disorder is modestly more common in men than in women. Nor is the outcome uniformly poor. A division of symptoms into positive, negative, and disorganisation syndromes is supported by factor analysis. Catatonic symptoms are not specific to schizophrenia and so-called first rank symptoms are no longer considered diagnostically important. Cognitive impairment is now recognised as a further clinical feature of the disorder. Lateral ventricular enlargement and brain volume reductions of around 2% are established findings. Brain functional changes occur in different subregions of the frontal cortex and might ultimately be understandable in terms of disturbed interaction among large-scale brain networks. Neurochemical disturbance, involving dopamine function and glutamatergic N-methyl-D-aspartate receptor function, is supported by indirect and direct evidence. The genetic contribution to schizophrenia is now recognised to be largely polygenic. Birth and early life factors also have an important aetiological role. The mainstay of treatment remains dopamine receptor-blocking drugs; a psychological intervention, cognitive behavioural therapy, has relatively small effects on symptoms. The idea that schizophrenia is better regarded as the extreme end of a continuum of psychotic symptoms is currently influential. Other areas of debate include cannabis and childhood adversity as causative factors, whether there is progressive brain change after onset, and the long-term success of early intervention initiatives.
Psychotic experiences in seven-year-old children with familial high risk of schizophrenia or bipolar disorder in: The Danish High Risk and Resilience Study – VIA 7; A population-based cohort study
2021, Schizophrenia Research
Citation Excerpt :
In contrast to the above studies, a family history of schizophrenia was not predictive of PEs in the ‘Avon Longitudinal Study of Parents and Children’ birth cohort of twelve-year-old children (Zammit et al., 2008). In line with this latter study, a study including adult siblings of individuals with schizophrenia did not find a higher occurrence of PEs in these relatives (Landin-Romero et al., 2016). PEs in children of parents with bipolar disorder is sparsely lit.
We aimed to examine the prevalence of psychotic experiences (PEs) in children with familial high risk of schizophrenia (FHR-SZ) or bipolar disorder (FHR-BP) and, in exploratory analyses, to examine the possible associations between PEs and mental disorders as well as level of functioning.
A cohort of seven-year-old children with FHR-SZ (N = 199), FHR-BP (N = 118) and controls (N = 196) was recruited through Danish nationwide registers. Lifetime PEs were assessed through interviews using the psychosis section of the ‘Schedule for Affective Disorders and Schizophrenia for School-Age Children - Present and Lifetime Version’ (K-SADS-PL). Lifetime DSM-IV diagnoses were ascertained through K-SADS-PL and the level of functioning of the children through ‘Children's Global Assessment Scale’.
Both children with FHR-SZ (OR = 2.9, 95% CI = 1.4–6.2, p = 0.005) and FHR-BP (OR = 2.9, 95% CI = 1.3–6.7, p = 0.011) had an increased risk of having experienced “severe” PEs compared with controls. In the overall cohort PEs were associated with any lifetime mental disorder, Attention-Deficit/Hyperactivity Disorder, anxiety disorders and a lower level of functioning.
The findings of a higher proportion of high risk children reporting PEs could represent an early manifestation of later more severe psychopathology or simply an unspecific transitory symptom. Future follow-up studies of this cohort will explore the predictive value of the occurrence of PEs at age seven.
Psychiatric framing affects positive but not negative schizotypy scores in psychology and medical students
2018, Psychiatry Research
Citation Excerpt :
Such self-report questionnaires tap the same subjective experiences as the interview techniques used in patient samples (Eaton et al., 1991; Raine, 1991), and have good predictive validity (Barrantes-Vidal et al., 2013; Chapman et al., 1994; Gooding et al., 2005). Given that there is a strong genetic component in psychosis, it is paradoxical that patient relatives often present with normal to low rates of positive schizotypy (e.g. Appels et al., 2004; Bora and Veznedaroglu, 2007; Calkins et al., 2004; Claridge et al., 1983; Clementz et al., 1991; Compton and Chien, 2008; Katsanis et al., 1990; Landin-Romero et al., 2016; Tarbox et al., 2012). Potentially, relatives report unexpectedly low positive schizotypy scores because of a defensive response1 tendency when asked about unusual experiences of the kind associated with the illness seen in the overtly psychotic family member (e.g. Claridge et al., 1983; Katsanis et al., 1990; Yaralian et al., 2000).
When testing risk for psychosis, we regularly rely on self-report questionnaires. Yet, the more that people know about this condition, the more they might respond defensively, in particular with regard to the more salient positive symptom dimension. In two studies, we investigated whether framing provided by questionnaire instructions might modulate responses on self-reported positive and negative schizotypy. The O-LIFE (UK study) or SPQ (New Zealand study) questionnaire was framed in either a “psychiatric”, “creativity”, or “personality” (NZ only) context. We tested psychology students (without taught knowledge about psychosis) and medical students (with taught knowledge about psychosis; UK only). We observed framing effects in psychology students in both studies: positive schizotypy scores were lower after the psychiatric compared to the creativity instruction. However, schizotypy scores did not differ between the creativity and personality framing conditions, suggesting that the low scores with psychiatric framing reflect defensive responding. The same framing effect was also observed in medical students, despite their lower positive schizotypy scores overall. Negative schizotypy scores were not affected by framing in either study. These results highlight the need to reduce response biases when studying schizotypy, because these might blur schizotypy-behaviour relationships.
Transdiagnostic dimensions of symptoms and experiences associated with immune proteins in the continuity of psychosis
2024, Psychological Medicine
Relationship between polygenic risk scores and symptom dimensions of schizophrenia and schizotypy in multiplex families with schizophrenia
2023, British Journal of Psychiatry
Environment-Wide Association Study (E<sup>n</sup>WAS) of Prenatal and Perinatal Factors Associated With Autistic Traits: A Population-Based Study
2020, Autism Research

View all citing articles on Scopus

View full text

Examining the continuum of psychosis: Frequency and characteristics of psychotic-like symptoms in relatives and non-relatives of patients with schizophrenia

Abstract

Background

Methods

Results

Conclusions

Section snippets

Subjects

Results

Discussion

Role of the funding source

Conflict of interest statement

Author contributions

Acknowledgements

Brain Cogn.

Schizophr. Res.

Clin. Psychol. Rev.

Schizophr. Res.

Schizophr. Res.

Clin. Psychol. Rev.

Schizophr. Res.

Emerging perspectives from the hearing voices movement: implications for research and practice

Schizophr. Bull.

Why we need more debate on whether psychotic symptoms lie on a continuum with normality

Psychol. Med.

The Structured Clinical Interview for DSM-IV Axis I Disorders (Research Version)

Schizophrenia and social class

Br. J. Psychiatry

Social class and mental illness: a community study. 1958

Am. J. Public Health

The Wide Range Achievement Test–Revised Administration Manual

Predicting schizophrenia: findings from the Edinburgh high-risk study

Br. J. Psychiatry

Diagnostic approaches to schizotypal personality disorder: a historical perspective

Schizophr. Bull.

The structured interview for schizotypy (SIS): a preliminary report

Schizophr. Bull.