Elsevier

Biological Psychiatry

Volume 57, Issue 12, 15 June 2005, Pages 1504-1509
Biological Psychiatry

Original article
P50 Suppression in Individuals at Risk for Schizophrenia: The Convergence of Clinical, Familial, and Vulnerability Marker Risk Assessment

https://doi.org/10.1016/j.biopsych.2005.03.003Get rights and content

Background

Identification of individuals at risk for the development of schizophrenia is important because it can lead to a greater understanding of the early stages of the illness. The aim of the present study was to determine whether individuals “at risk” for schizophrenia have deficits in P50 suppression, a preattentive measure of sensory gating.

Methods

Thirty-one at-risk and 21 normal comparison subjects were referred to the CARE (Cognitive Assessment and Risk Evaluation) Program at University of California San Diego. The primary aim of the CARE Program is to identify individuals who are at the greatest risk for conversion to psychosis, with a combination of clinical, familial, and vulnerability markers, including P50 suppression.

Results

As a group, the at-risk subjects had modestly lower levels (effect size = .43) of P50 suppression (55.1%, SD = 39.8) relative to comparison subjects (71.5%, SD = 34.7). At-risk subjects with a first-degree relative with schizophrenia had profoundly deficient P50 suppression (16.4%, SD = 33.8) compared with other at-risk (p < .05) and comparison subjects (p < .005).

Conclusions

Ongoing longitudinal follow-up studies will determine whether it is possible to improve the predictive validity of the clinical and familial variables by using P50 suppression alone or in combination with other measures in determining which individuals are at greatest risk for schizophrenia.

Section snippets

Participants

Thirty-one individuals (aged 12–30 years) at risk for schizophrenia were recruited throughout the community of San Diego. The at-risk subjects were compared with 21 age-matched normal comparison subjects. All subjects provided written informed consent after the procedures were fully explained (UCSD IRB# 030829).

Recruitment and Assessment

Individuals classified as “at risk” for schizophrenia were identified through a broad community outreach program. Educational lectures regarding schizophrenia and the prodromal symptoms

Results

There were no statistically significant differences between groups in the amplitude [t(50) = .06, ns] or latency [t(50) = .7, ns] of the P50 response to the first stimulus or the amplitude [t(50) = −1.0, ns] or latency [t(35) = −.06, ns] of the P50 response to the second stimulus (see Figure 2) according to t tests. Nine of the 31 at-risk subjects and 6 of the 21 comparison subjects did not have an identifiable P50 response to the second stimulus (Fisher exact test, ns). The P50 suppression of

Discussion

At-risk individuals with a family history of schizophrenia in a first-degree relative have reduced P50 suppression compared with demographically matched normal comparison subjects, as well as with other individuals identified as being at risk for developing schizophrenia on the basis of subsyndromal or brief episodes of psychotic symptoms. As a group, individuals who have a familial risk and/or are clinically at risk for schizophrenia have reduced P50 ERP suppression and differ from normal

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      Moreover, Grootens et al. (2008) reported a significantly greater difference between P50 for S1 and P50 for S2 in BPD patients as compared to HC, which was mainly due to a greater S1 response. P50 sensory gating is implied in the ability to filter the relevant stimulus at a pre-attentional level and its reduction was frequently identified in schizophrenic patients (Hamilton et al., 2018; Shen et al., 2020), making it a possible marker of vulnerability to psychosis (Cadenhead et al., 2005; Olincy and Martin, 2005). Therefore, the reduced P50 sensory gating observed by Niemantsverdriet et al. (2019) in BPD patients with AVH could indicate a vulnerability to psychosis.

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