Maarten Bak

Childhood abuse as a risk factor for psychotic experiences.

Objective: To examine the hypothesis that individuals from the general population who report childhood abuse are at increased risk of developing positive psychotic symptoms.

The incidence and outcome of subclinical psychotic experiences in the general population.

OBJECTIVES To examine the incidence and 2-year stability and outcome of subclinical psychotic experiences in the general population. DESIGN The Netherlands Mental Health Survey and Incidence Study (NEMESIS), a longitudinal general population study. METHODS A representative population sample of 7,076 participants was interviewed with the composite international diagnostic interview at baseline, 1 year later at T(1) and again 2 years later at T(2). A sample of individuals was identified who had onset of a new, broadly defined psychotic experience between baseline and T(1) (N = 79; incidence = 2%). Stability and outcome of these incident positive psychotic experiences was reassessed by interview at T(2), at which 25 individuals had a CIDI rating of broadly defined psychotic experience (subclinical outcome) and 11 individuals had psychotic experiences with functional impairment and need for care (clinical outcome). RESULTS The majority of individuals with an incident psychotic experience did not display persistence of the experience. Only 8% of individuals with a T1 incident psychotic experience had evidence of a T2 subclinical outcome, and only 8% had evidence of a T2 clinical outcome. The emotional context and the number of the T1 incident psychotic experiences were strong modifiers of predictive power for the clinical outcome, but not (or to a much lesser extent) for the subclinical outcome. CONCLUSIONS The incidence of positive psychotic experiences in the general population is around 100 times greater than traditional estimates of incidence of psychotic disorder such as schizophrenia. The far most likely outcome for these experiences is discontinuity. For the small proportion who display continuity, there is an equally large likelihood of subclinical and clinical 2-year outcomes. Emotional appraisal and degree of intrusiveness of psychotic experiences are important modifiers not for continuity per se but for clinical outcome specifically.

Validity and reliability of the CAPE: a self-report instrument for the measurement of psychotic experiences in the general population

Objective:  General population longitudinal cohort studies have demonstrated the prognostic validity of self‐reported psychotic experiences, but data on reliability and cross‐validation with interview‐based measures of these experiences are sparse. This study tested the reliability and validity of the Community Assessment of Psychic Experiences (CAPE42).

Neuroticism and low self-esteem as risk factors for psychosis

Background Low self-esteem and high neuroticism are common features in psychosis, but in the absence of longitudinal studies it is unclear whether they represent consequences of the illness or risk factors acting before illness onset. Methods A population sample of 3,929 individuals with no lifetime evidence of psychosis were interviewed with the Composite International Diagnostic Interview and were administered the Groningen Neuroticism Scale and the Rosenberg Self-Esteem Scale at baseline and 1 and 3 years later. At year 3, individuals with CIDI evidence of psychotic symptoms were interviewed by clinicians to identify incident psychotic or psychosis-like symptoms. Results Baseline neuroticism and self-esteem predicted first-ever onset of psychotic symptoms at year 3 (neuroticism, OR 1.16, 95 % CI 1.09, 1.23; self-esteem, OR 1.09, 95 % CI 1.01, 1.18). When adjusted for each other and for level of anxiety and depression, neuroticism was the strongest independent predictor for onset of psychotic symptoms (OR 1.16, 95 % CI 1.07, 1.26). Conclusions Neuroticism increases the risk for development of psychotic symptoms. Mechanisms of risk may involve certain cognitive styles associated with neuroticism, such as beliefs about the uncontrollability of certain events and experiences. The association between low self-esteem and psychosis may involve the area of overlap between self-esteem and neuroticism.

Almost All Antipsychotics Result in Weight Gain: A Meta-Analysis

Introduction Antipsychotics (AP) induce weight gain. However, reviews and meta-analyses generally are restricted to second generation antipsychotics (SGA) and do not stratify for duration of AP use. It is hypothesised that patients gain more weight if duration of AP use is longer. Method A meta-analysis was conducted of clinical trials of AP that reported weight change. Outcome measures were body weight change, change in BMI and clinically relevant weight change (7% weight gain or loss). Duration of AP-use was stratified as follows: ≤6 weeks, 6–16 weeks, 16–38 weeks and >38 weeks. Forest plots stratified by AP as well as by duration of use were generated and results were summarised in figures. Results 307 articles met inclusion criteria. The majority were AP switch studies. Almost all AP showed a degree of weight gain after prolonged use, except for amisulpride, aripiprazole and ziprasidone, for which prolonged exposure resulted in negligible weight change. The level of weight gain per AP varied from discrete to severe. Contrary to expectations, switch of AP did not result in weight loss for amisulpride, aripiprazole or ziprasidone. In AP-naive patients, weight gain was much more pronounced for all AP. Conclusion Given prolonged exposure, virtually all AP are associated with weight gain. The rational of switching AP to achieve weight reduction may be overrated. In AP-naive patients, weight gain is more pronounced.

Development of depressed mood predicts onset of psychotic disorder in individuals who report hallucinatory experiences

OBJECTIVES Current psychological theories state that the clinical outcome of hallucinatory experiences is dependent on the degree of associated distress, anxiety, and depression. This study examined the hypothesis that the risk for onset of psychotic disorder in individuals with self-reported hallucinatory experiences would be higher in those who subsequently developed depressed mood than in those who did not. DESIGN A prospective cohort study of a general population sample. METHODS A sample of 4,670 individuals with no lifetime evidence of any psychotic disorder were interviewed with the Composite International Diagnostic Interview Schedule (CIDI) at baseline and 1 and 3 years later. At Year 3, individuals with CIDI evidence of psychotic symptoms were interviewed by clinicians to identify potential onset of psychotic disorder. Psychotic disorder was specified at three levels; two involving severity of positive symptoms of psychosis, and one using additional clinical judgment of need for care. RESULTS Given the presence of hallucinatory experiences at baseline, the increase in risk of having the psychosis outcome at Year 3 was higher in the group with depressed mood at Year 1 than in the group without depressed mood at Year 1 (any level of psychotic symptoms: risk difference 17.0%, 95% CI - 1.7, 35.7; severe level of psychotic symptoms: risk difference 21.7%, 95% CI 3.2, 40.2; needs-based diagnosis of psychotic disorder: risk difference 16.8%, 95% CI 0.4, 33.3). CONCLUSION The results are in line with current psychological models of psychosis that emphasize the role of secondary appraisals of psychotic experiences in the onset of clinical disorder.

Early trauma may increase the risk for psychotic experiences by impacting on emotional response and perception of control

Objective:  Exposure to early trauma may increase the risk of dysfunctional responses to anomalous psychotic experiences resulting in psychotic symptom formation.

Hallucinatory experiences and onset of psychotic disorder: evidence that the risk is mediated by delusion formation

Objective:  To examine the hypothesis that the risk for onset of psychotic disorder in individuals with self‐reported hallucinatory experiences (HE) would be higher in those who developed delusional ideation (DE) than in those who did not.

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 represent the softest expression of an extended psychosis phenotype that is phenotypically continuous with clinical psychosis but discontinuous in need for care.

Explaining transitions over the hypothesized psychosis continuum.

OBJECTIVES It is crucial to understand the psychological mechanisms that mediate transition from having one or two psychotic symptoms to becoming a patient with a psychotic disorder. This study investigated whether: (i) a delusional interpretation and/or a depressed response to hallucinatory experiences predicts the later onset of clinical psychotic disorder; and (ii) the presence of need for care in relation to psychotic disorder was associated with the use of particular coping strategies. METHOD A general population sample of 4672 individuals with no lifetime evidence of any psychotic disorder were interviewed with the Composite International Diagnostic Interview Schedule (CIDI) at baseline and 1 and 3 years later. At year 3, individuals with CIDI evidence of psychotic symptoms were interviewed by clinicians to identify onset of psychotic disorder with need for care. Coping, subjective distress with and perceived control over the psychotic experience were assessed using the Maastricht Assessment of Coping Strategies (MACS). RESULTS Given the presence of hallucinatory experiences at baseline, the increase in risk on the additive scale of having the psychosis outcome at T2 was higher in the group with delusional ideation at T1 than in those without delusional ideation at T1. Similarly, presence of depressed mood at T1 increased the risk of having the psychosis outcome at T2, but this effect overlapped partly with the risk-increasing effect of delusional ideation. Individuals with a need for care were much more likely to display symptomatic coping, whereas the presence of the other coping types was not different across the groups with and without need for care. CONCLUSION Transitions over the psychosis continuum are, at least in part, driven by the emotional, cognitive and behavioural responses to the initial psychotic or psychosis-like experiences. Individuals who react with a delusional interpretation, negative emotional states and/or a symptomatic coping style have an increased risk for developing clinical psychosis.