Cannabis use and dimensions of psychosis in a nonclinical population of female subjects

OBJECTIVE: The aim of the present study was to explore the pattern of associations between cannabis use and dimensions of psychosis in a nonclinical population of female subjects. METHOD: The Community Assessment of Psychic Experiences (CAPE), a 42-item self-report questionnaire that evolved from the Peters et al. Delusions Inventory [Schizophr. Bull. 25 (1999) 553], was used to measure dimensions of psychosis in a sample of undergraduate female students (n=571). The participants were also asked to complete a self-report questionnaire collecting information on substance use. RESULTS: Three correlated dimensions of positive, negative and depressive experiences were identified using principal components factor analysis. Frequency of cannabis use was independently associated with the intensity of both positive and negative psychotic experiences. No significant association was found between cannabis use and the depressive dimension, or between alcohol use and any of the three positive, negative and depressive dimensions. CONCLUSION: This cross-sectional study supports the hypothesis that exposure to cannabis may induce the emergence of positive psychotic symptoms in subjects without clinical psychosis, and additionally suggests that cannabis users exhibit greater levels of negative symptoms. Prospective studies are required to explore the direction of causality and the impact of cannabis on the course of psychotic experiences in subjects from the general population.     

The psychosis continuum and categorical versus dimensional diagnostic approaches

This overview briefly presents recent thinking on the dimensional approach to understanding psychotic experiences. First, evidence is provided for a continuum of psychosis ranging from self-reported infrequent psychotic symptoms in the general population, to schizotypal traits, to schizotypal personality disorder, and finally to full-blown psychosis resulting in a diagnosable primary psychotic disorder. Variation within each of these types of psychotic experience is discussed. Then, a comparison is presented between categorical and dimensional approaches to the diagnosis of psychosis by highlighting four advantages of each approach. In doing so, it is emphasized that the categorical approach is beneficial primarily in terms of reliability, whereas the dimensional approach would enhance validity.     

Early trauma and familial risk in the development of the extended psychosis phenotype in adolescence

Wigman JTW, van Winkel R, Ormel J, Verhulst FC, van Os J, Vollebergh WAM. Early trauma and familial risk in the development of the extended psychosis phenotype in adolescence. Objective: Both genetic and environmental factors are thought to play a role in the development of psychotic outcomes; however, their respective contributions over time, including possible developmental interactions, remain largely unknown. Method: The contribution of parental general and psychotic psychopathology as proxies of genetic risk to the development of subthreshold psychosis and its hypothesized interaction with childhood trauma were studied in a general population sample of 2230 adolescents, followed from age 10–16 years. Outcome measures were: i) level of psychotic experiences at age 16 years and ii) persistence of such experiences over the total follow‐up period. Results: General parental psychopathology was associated with CAPE score (OR = 1.08; P < 0.043 for highest quintile) and suggestively predicted psychosis persistence (OR, 1.16; P < 0.072). Psychotic parental psychopathology was suggestively associated with CAPE score (OR, 2.25; P < 0.063 for highest quintile), predicted membership of the Persistent group (OR, 3.72; P < 0.039) and suggestively predicted membership of the Decreasing group (OR 2.04; P < 0.051). Childhood trauma was associated with CAPE score and with all developmental trajectories of subclinical psychosis. No evidence was found for an interaction between trauma and parental psychopathology. Conclusion: The development and persistence of subthreshold psychotic symptoms may be conditional on non‐interacting proxy genetic and environmental influences.     

How psychotic are individuals with non-psychotic disorders?

BACKGROUND: The objective of this study was to compare, using a self-report questionnaire, the dimensions of psychosis across different patient groups in a community mental health service (CMHS) and in non-patients in the general population. METHODS: The Community Assessment of Psychic Experiences (CAPE) is a 40-item self-report instrument with positive, negative and depressive symptom dimensions. Seven hundred and sixty-two patients and 647 subjects in the general population filled in the CAPE. In 555 of the 762 patients, a DSM-IV diagnosis was made. The following DSM-IV categories were used in the analyses: 1. Schizophrenia and Other Psychotic Disorders (n = 72), 2. Mood Disorders (n = 214), 3. Anxiety Disorders (n = 129). The patient and non-patient groups were compared on the three dimensions of the CAPE using multivariate regression analysis. RESULTS: The patient groups scored significantly higher on the positive, negative and depressive dimensions than the non-patients. Patients with psychotic disorders had the greatest difference in positive psychosis items compared to non-patients (beta = 0.94, 95 % CI: 0.7-1.18), whereas patients with mood and anxiety disorders had the highest depressive symptom scores, and positive symptom scores that were intermediate to that of non-patients and patients with psychotic disorders (mood disorders: beta = 0.53, 95 % CI: 0.39-0.68; anxiety disorders: beta = 0.22, 95 % CI: 0.04-0.39). The CAPE distress score adjusted for the corresponding frequency score was not significantly different between the patient groups, but compared to the general population, patient status did contribute significantly to the level of distress. DISCUSSION: Patients with anxiety and mood disorders had elevated scores on positive psychosis items, indicating that expression of psychosis in non-psychotic disorders is common. The finding of elevated scores of the patient groups on all three dimensions compared to non-patients suggests that the psychopathology associated with psychotic disorders varies quantitatively across DSM-IV categories.     

The Cardiff Anomalous Perceptions Scale (CAPS): a new validated measure of anomalous perceptual experience

The study describes the Cardiff Anomalous Perceptions Scale (CAPS), a new validated measure of perceptual anomalies. The 32-item CAPS measure is a reliable, self-report scale, which uses neutral language, demonstrates high content validity, and includes subscales that measure distress, intrusiveness, and frequency of anomalous experience. The CAPS was completed by a general population sample of 336 participants and 20 psychotic inpatients. Approximately 11% of the general population sample scored above the mean of the psychotic patient sample, although, as a group, psychotic inpatients scored significantly more than the general population on all CAPS subscales. A principal components analysis of the general population data revealed 3 components: "clinical psychosis" (largely Schneiderian first-rank symptoms), "temporal lobe disturbance" (largely related to temporal lobe epilepsy and related seizure-like disturbances) and "chemosensation" (largely olfactory and gustatory experiences), suggesting that there are multiple contributory factors underlying anomalous perceptual experience and the "psychosis continuum."     

A self-reported instrument for prodromal symptoms of psychosis: testing the clinical validity of the PRIME Screen-Revised (PS-R) in a Japanese population

OBJECTIVE: Early intervention for psychosis requires an easy, useful assessment instrument to identify subjects with prodromal symptoms at an early stage. The aim of this study was to test the clinical validity of the PRIME Screen-Revised (PS-R), a 12-item self-reported instrument for prodromal symptoms of psychosis, by comparing the results for a non-clinical population with those for a clinical population. METHOD: The PS-R was administered to 1,024 subjects (496 students and 528 outpatients). Of the 528 patients, 115 were randomly recruited and tested using the Structured Interview for Prodromal Syndromes (SIPS) to determine the concordant validity of the PS-R. The predictive validity of the PS-R was measured by determining the transition rate to psychosis during a 6-month follow-up period. RESULTS: The specificity and sensitivity of the PS-R, using the SIPS as a gold standard, were 0.74 and 1.00. The concordant validity of the PS-R against the SIPS was 0.43. The predictive validity of the PS-R and the SIPS, defined as the transition rate to psychosis, were 0.11 and 0.25, respectively. None of the patients with negative PS-R results developed psychosis. CONCLUSIONS: Our findings showed that the PS-R was highly valid and that its usage is feasible in both general practice and clinical settings. This self-reported instrument represents a useful screening tool for alerting clinicians to subjects with psychotic prodromal symptoms.     

Phenotypically continuous with clinical psychosis, discontinuous in need for care: evidence for an extended psychosis phenotype

Background:

Rates of self-reported psychotic experiences (SRPEs) in general population samples are high; however the reliability against interview-based assessments and the clinical significance of false-positive (FP) ratings remain unclear. Design: The second Netherlands Mental Health Survey and Incidence Study-2, a general population study.

Methods:

Trained lay interviewers administered a structured interview assessing psychopathology and psychosocial characteristics in 6646 participants. Participants with at least one SRPE (N = 1084) were reassessed by clinical telephone interview.

Results:

Thirty-six percent of participants with SRPEs were confirmed by clinical interview as true positive (TP). SPREs not confirmed by clinical interview (FP group) generated less help-seeking behavior and occurred less frequently compared with TP experiences (TP group). However, compared with controls without psychotic experiences, the FP group more often displayed mood disorder (relative risk [RR] 1.7, 1.4–2.2), substance use disorder (RR 2.0, 1.6–2.6), cannabis use (RR 1.5, 1.2–1.9), higher levels of neuroticism (RR 1.8, 1.5–2.2), affective dysregulation, and social dysfunction. The FP group also experienced more sexual (RR 2.0, 1.5–2.8) and psychological childhood trauma (RR 2.1, 1.7–2.6) as well as peer victimization (RR 1.5, 1.2–2.0) and recent life events (RR 2.0, 1.6–2.4) than controls without psychotic experiences. Differences between the FP group and the TP group across these domains were much smaller and less conclusive.

Discussion:

SRPEs not confirmed by clinical interview may epresent the softest expression of an extended psychosis phenotype that is phenotypically continuous with clinical psychosis but discontinuous in need for care.     

Self‐reported psychotic experiences in the general population: a valid screening tool for DSM‐III‐R psychotic disorders?

OBJECTIVE: To examine the diagnostic value of self-reported psychotic-like experiences for DSM-III-R psychotic disorders. METHOD: A general population sample of 7076 subjects aged 18-64 years was interviewed with the Composite International Diagnostic Interview (CIDI) and, if there was evidence of psychotic experiences, the Structured Clinical Interview for DSM-III-R. RESULTS: The probability of having a psychotic disorder increased in a dose-response fashion with the level of self-reported psychotic experiences, but individual CIDI psychotic experience ratings had relatively low post-test probabilities (PPs) (range: 5.1-26.5%). However, limiting the sample to individuals who had been in contact with mental health services substantially improved PPs (range: 13.3-43.1%). CONCLUSION: Screening for psychosis in the population carries a high risk of stigmatization in false-positive cases and violation of the right 'not to know' in true-positive cases. However, in mental health care users, self-reported psychotic experiences may be a useful screening tool in individuals who have already developed help-seeking.     

Improving detection of first-episode psychosis by mental health-care services using a self-report questionnaire

Objective: To examine the utility of the Community Assessment of Psychic Experiences (CAPE)‐42, a self‐report questionnaire, to improve detection of first‐episode psychosis in new referrals to mental health services. Method: At first contact with mental health‐care services patients were asked to complete the CAPE‐42 and were then routinely diagnosed by a clinician. Standard diagnoses were obtained by means of the mini‐Schedule for Clinical Assessment in Neuropsychiatry. Results: Of the 246 included patients, 26 (10.6%) were diagnosed with psychosis according to the mini‐Schedule for Clinical Assessment in Neuropsychiatry. Only 10 of them were recognized by clinical routine, and 16 psychotic patients were not properly identified. Using an optimal cut‐off of 50 on the frequency or distress dimension of the positive subscale of the CAPE‐42 detected 14 of these misdiagnosed patients. The sensitivity of the CAPE‐42 at this cut‐off point was 77.5 and the specificity 70.5. Conclusion: Systematic screening of patients using a self‐report questionnaire for psychotic symptoms improves routine detection of psychotic patients when they first come into contact with mental health services.     

The reliability and validity of general psychotic rating scales with people with mild and moderate intellectual disabilities: an empirical investigation

Background Whilst assessment tools have been developed to diagnose schizophrenia in people with mild intellectual disabilities (IDs), little attention has been paid to developing reliable and valid dimensional measures of psychotic experiences with this population. This study investigates the reliability and validity of two such measures developed for the general adult psychiatric population, the Positive and Negative Syndrome Scale (PANSS) and the Psychotic Symptom Rating Scales (PSYRATS), with a population of adults with mild IDs. Method Sixty-two adults with mild IDs were interviewed using the PANSS and PSYRATS, and independently interviewed using the Psychiatric Assessment Schedule – Adults with Developmental Disability (PAS-ADD) to obtain psychiatric diagnoses to the criteria of the International Classification of Diseases – Tenth Revision (ICD-10). On the basis of ICD-10 diagnosis, participants were divided into three groups: psychosis (n = 11); other mental health problem (n = 14); no mental health problem (n = 37). PANSS and PSYRATS subscale scores were compared across these three groups and were correlated with PAS-ADD symptom scores across a number of PAS-ADD symptom domains. Results All PANSS and PSYRATS subscales showed adequate internal reliability, largely good test-retest reliability, and logical inter-correlations between subscales. The PANSS positive symptoms and the PSYRATS auditory hallucinations subscales differentiated between the psychosis group and the other groups; the PANSS general symptoms subscale differentiated between the psychosis and no mental health problem groups; and the PANSS negative symptoms and the PSYRATS delusions subscales did not differentiate between the three groups. Conclusions The PANSS and PSYRATS are promising measures for use with people with mild IDs and psychotic experiences, although further investigation of items relating to negative symptoms and delusions is warranted.     

Do different psychotic experiences differentially predict need for care in the general population?

INTRODUCTION: The pathway from subclinical psychotic experiences to need for care may depend on type of psychotic experience, level of associated distress, and previous experience of psychosis. METHOD: In a general population sample with no previous Diagnostic and Statistical Manual of Mental Disorders , Revised Third Edition , psychotic disorder (n = 4722), 83 subjects displayed at least one psychotic experience. Within the group of 83, subjects with (n = 24) and without need for care (n = 59) were compared. Presence of psychotic experiences at younger ages had been assessed at earlier interviews. RESULTS: Of 7 different psychotic experiences, only hearing voices, nonverbal hallucinations, and passivity phenomena were significantly associated with need for care. These associations were largely explained by the distress associated with the psychotic experience, but whether individuals had had psychotic experiences at earlier ages did not matter. CONCLUSIONS: Different psychotic experiences differ in the associated level of need for care and the mediating role of distress. Longer prior exposure to psychosis may not influence the pathway from subclinical to clinical.     

Characterization of Psychotic Experiences in Adolescence Using the Specific Psychotic Experiences Questionnaire: Findings From a Study of 5000 16-Year-Old Twins

We aimed to characterize multiple psychotic experiences, each assessed on a spectrum of severity (ie, quantitatively), in a general population sample of adolescents. Over five thousand 16-year-old twins and their parents completed the newly devised Specific Psychotic Experiences Questionnaire (SPEQ); a subsample repeated it approximately 9 months later. SPEQ was investigated in terms of factor structure, intersubscale correlations, frequency of endorsement and reported distress, reliability and validity, associations with traits of anxiety, depression and personality, and sex differences. Principal component analysis revealed a 6-component solution: paranoia, hallucinations, cognitive disorganization, grandiosity, anhedonia, and parent-rated negative symptoms. These components formed the basis of 6 subscales. Correlations between different experiences were low to moderate. All SPEQ subscales, except Grandiosity, correlated significantly with traits of anxiety, depression, and neuroticism. Scales showed good internal consistency, test-retest reliability, and convergent validity. Girls endorsed more paranoia, hallucinations, and cognitive disorganization; boys reported more grandiosity and anhedonia and had more parent-rated negative symptoms. As in adults at high risk for psychosis and with psychotic disorders, psychotic experiences in adolescents are characterized by multiple components. The study of psychotic experiences as distinct dimensional quantitative traits is likely to prove an important strategy for future research, and the SPEQ is a self- and parent-report questionnaire battery that embodies this approach.Key words: paranoia, hallucinations, grandiosity, anhedonia, adolescence, schizophrenia     

Assessing Anomalous Perceptual Experiences in Nonpsychiatric Individuals and Outpatients with Psychosis in Taiwan: An Investigation Using the Cardiff Anomalous Perceptions Scale (CAPS)

The Cardiff anomalous perceptions scale (CAPS) has been recently designed for the assessment of anomalous perceptual experiences in the general population, and includes dimensions that measure distress, intrusiveness, and frequency. The purpose of this study was to assess the psychometric properties of a Taiwanese version of the CAPS. The English version of the CAPS was translated into Taiwanese (CAPS-T) and the latter was applied to this study. We administered the questionnaire to a consecutive sample of 192 participants with (n = 106; clinical group including schizophrenia and affective psychosis) or without psychotic disorders (n = 86; non-clinical group). In addition to the CAPS-T, the Taiwanese version of the brief psychiatric symptom rating scale (BSRS) measured the severity of the psychopathology. We also tested the psychometric properties of the CAPS-T including construct validity, internal consistency, test–retest reliability, and convergent and discriminative validity. Overall, the CAPS-T showed good construct validity, internal consistency, and stability over time and correlated significantly with the psychoticism subscale of the BSRS. As predicted, the mean differences in CAPS-T scores between participants with or without a psychotic disorder were significant. Convergent and discriminative validity were satisfactory. A score of 5 was found to the best threshold in discriminating between clinical and non-clinical samples. Our findings indicate that the Taiwanese version of the CAPS is a reliable and valid instrument to measure the multidimensionality of perceptual anomalies in general and appears to complement the clinical measures of psychosis proneness in Taiwan.     

Data Gathering: Biased in Psychosis?

This study examined whether the probabilistic reasoning bias referred to as a "jumping-to-conclusions" (JTC) style of reasoning, which, according to previous research, is associated with particular psychotic symptoms such as delusions, represents a trait that can also be detected in nonpsychotic relatives of patients with schizophrenia and in nonpsychotic individuals with a high level of psychotic experiences. Participants were, in order of level of psychosis liability, 40 patients with schizophrenia or a schizoaffective disorder, 40 first-degree nonpsychotic relatives, 41 participants from the general population with above average expression of psychotic experiences, and 53 participants from the general population with an average level of psychotic experiences. A "jumping-to-conclusions" bias was assessed using the beads task. A dose-response relationship was found in the association between level of psychosis liability and JTC (defined as needing only a single bead to complete the beads task) (odds ratio [OR] linear trend = 1.59, 95% CI: 1.13-2.24), and, independently, alinear association was apparent between JTC and level of delusional ideation (OR linear trend = 2.59, 95% CI: 1.18-5.69). In addition, the association between psychosis liability and JTC was generally much stronger as the level of delusional ideation was higher. JTC is associated with liability to psychosis (trait), in particular if the psychosis phenotype is characterized by delusional ideation (state).     

Replication of dissociation-psychosis link in New Zealand students and inmates

To assess the relationship between dissociative and psychotic experiences, New Zealand university students (N = 119) and prison inmates (N = 42) were administered the Dissociative Experiences Scale (DES) and Symptom Checklist-90-Revised (SCL-90-R). Strong correlations were found between DES scores and the psychoticism and paranoid ideation subscales of the SCL-90-R (students: r = .520, .517, respectively; inmates: r = .637, .649, respectively). While other correlations were also significant (but smaller), these results are consistent with previous studies that have used a range of measures of psychosis or schizotypy with a variety of clinical and nonclinical populations. Such consistent findings in the face of methodological diversity offer strong support for the validity of a link between the concepts of dissociation and psychosis. While this relationship has previously been interpreted indirectly, as dissociative experiences predisposing to psychotic symptoms, we suggest a direct route: that dissociative experiences of various forms may underlie some (or even all) psychotic symptoms.     

Latent structure of psychotic experiences in the general population

Ahmed AO, Buckley PF, Mabe PA. Latent structure of psychotic experiences in the general population. Objective: There have been increasing pressures to adopt or incorporate dimensional representations in various sections of DSM‐5 including the psychotic disorders section. Thus far, findings offered as evidence of a continuous distribution of psychosis are limited given their exclusive focus on the manifest rather than latent structure of psychotic experiences. The current study sought to determine whether or not psychotic experiences possess a taxonic or dimensional latent structure. Method: We investigated the latent structure of psychotic experiences in the Collaborative Psychiatric Epidemiological Surveys (CPES) and the National Comorbidity Survey (NCS). We analyzed responses of participants in these surveys with three multivariate taxometric procedures (MAMBAC, MAXEIG, and L‐Mode) after summing responses on the surveys into three indicators of positive psychosis. Results: Taxometric results tended to support a dimensional, rather than taxonic structure for psychotic experiences. In the CPES, all taxometric methods produced graphical and numerical support for a dimensional structure. In the NCS, MAMBAC appeared to slightly support a taxonic structure, whereas MAXEIG and L‐Mode supported a dimensional structure. Conclusion: There appears to be a dimensional distribution of psychotic experiences in the general population. This supports the incorporation of dimensional representations of psychotic symptoms in the current diagnostic system.     

The Independent Effects of Psychosocial Stressors on Subclinical Psychosis: Findings From the Multinational EU-GEI Study

The influence of psychosocial stressors on psychosis risk has usually been studied in isolation and after the onset of the disorder, potentially ignoring important confounding relationships or the fact that some stressors that may be the consequence of the disorder rather than preexisting. The study of subclinical psychosis could help to address some of these issues. In this study, we investigated whether there was (i) an association between dimensions of subclinical psychosis and several psychosocial stressors including: childhood trauma, self-reported discrimination experiences, low social capital, and stressful life experiences, and (ii) any evidence of environment–environment (ExE) interactions between these factors. Data were drawn from the EUGEI study, in which healthy controls (N = 1497) and siblings of subjects with a psychotic disorder (N = 265) were included in six countries. The association between psychosocial stressors and subclinical psychosis dimensions (positive, negative and depressive dimension as measured by the Community Assessment of Psychic Experiences (CAPE) scale) and possible ExE interactions were assessed using linear regression models. After adjusting for sex, age, ethnicity, country, and control/sibling status, childhood trauma (β for positive dimension: 0.13, negative: 0.49, depressive: 0.26) and stressful life events (positive: 0.08, negative: 0.16, depressive: 0.17) were associated with the three dimensions. Lower social capital was associated with the negative and depression dimensions (negative: 0.26, depressive: 0.13), and self-reported discrimination experiences with the positive dimension (0.06). Our findings are in favor of independent, cumulative and non-specific influences of social adversities in subclinical psychosis in non-clinical populations, without arguments for E × E interactions.     

Correlates of perceptual distortions in clinical and non-clinical populations using the Cardiff Anomalous Perceptions Scale (CAPS): associations with anxiety and depression and a re-validation using a representative population sample

Although the literature on hallucinations in psychiatric patients shows clear links with anxiety and depression, associations of affect with a wider array of anomalous perceptual experiences have been much less studied. This study investigated patients with psychosis (N = 29) and a non-clinical population (N = 193) using the Cardiff Anomalous Perceptions Scale (CAPS), a measure of perceptual distortion and associated distress, intrusiveness and frequency; along with measures of depression, anxiety and worry. The study also allowed a re-validation of the CAPS in a more representative sample of the UK population. Moderate, reliable correlations with depression, anxiety and worry were found in the non-clinical population with the association being stronger in psychotic patients. The study re-confirmed that anomalous perceptual experiences are common in the general population and that a significant minority (11.9%) have higher levels than the mean of psychotic patients. Scale reliability and validity were also re-confirmed, and the CAPS score was found to be unrelated to age or gender in either sample. As in the original study, factor analysis produced a three-factor solution, although factor theme was not fully replicated: as before, a cluster of first-rank symptoms emerged, but with equivocal evidence for a temporal lobe factor and no replication of a ‘chemosensation’ component.     

Validity and usefulness of the Wisconsin Manual for Assessing Psychotic-like Experiences.

The Wisconsin Manual for Assessing Psychotic-like Experiences is an interview-based assessment system for rating psychotic and psychotic-like symptoms on a continuum of deviancy from normal to grossly psychotic. The original manual contained six scales, assessing thought transmission, passivity experiences, thought withdrawal, auditory experiences, personally relevant aberrant beliefs, and visual experiences. A seventh scale assessing deviant olfactory experiences was subsequently added. The rating scales have good interrater reliability when used by trained raters. Cross-sectional studies indicated that the frequency and deviancy of psychotic-like experiences are elevated among college students who were identified, hypothetically, as psychosis prone by other criteria. Psychotic-like experiences of moderate deviancy in college students successfully predicted the development of psychotic illness and poorer overall adjustment 10 years later. The manual is useful for identifying psychosis-prone individuals and is recommended for use in linkage and treatment outcome studies. The present article provides an interview schedule for collecting information required for rating psychotic-like experiences.     

Testing the psychosis continuum: differential impact of genetic and nongenetic risk factors and comorbid psychopathology across the entire spectrum of psychosis

A growing number of studies demonstrate high rates of subthreshold psychotic experiences, but there is considerable heterogeneity in rates due to study cohort and design factors, obscuring how prevalent psychotic experiences may or may not relate to rare psychotic disorders. In a representative general population sample (n = 4011) in Izmir, Turkey, the full spectrum of expression of psychosis was categorized across 5 groups representing (1) absence of psychosis, (2) subclinical psychotic experiences, (3) low-impact psychotic symptoms, (4) high-impact psychotic symptoms, and (5) full-blown clinical psychotic disorder and analyzed for continuity and discontinuity in relation to (1) other symptom dimensions associated with psychotic disorder and (2) proxies of genetic and nongenetic etiology. Results were tested for linear and extralinear contrasts between clinical and nonclinical and between disorder and nondisorder expression of psychosis. Demographic variables, indexing premorbid social adjustment and socioeconomic status, impacted mostly linearly; proxy variables of genetic loading (more or more severely affected relatives) impacted in a positive extralinear fashion; environmental risk factors sometimes impacted linearly (urbanicity and childhood adversity) and sometimes extralinearly (cannabis), occasioning a disproportional shift in risk at the clinical disorder end of the spectrum. Affective symptoms were associated with a disproportionally higher risk below the disorder threshold, whereas a disproportionally higher risk above the threshold was associated with psychotic symptom load, negative symptoms, disorganization, and visible signs of mental illness. Liability associated with respectively affective and nonaffective symptom domains, in interaction with environmental risks, may operate by impacting differentially over a quasi-continuous extended psychosis phenotype in the population.