A systematic review of all reported incidence and prevalence studies of population rates of subclinical psychotic experiences reveals a median prevalence rate of around 5% and a median incidence rate of around 3%. A meta-analysis of risk factors reveals associations with developmental stage, child and adult social adversity, psychoactive drug use, and also male sex and migrant status. The small difference between prevalence and incidence rates, together with data from follow-up studies, indicates that approximately 75-90% of developmental psychotic experiences are transitory and disappear over time. There is evidence, however, that transitory developmental expression of psychosis (psychosis proneness) may become abnormally persistent (persistence) and subsequently clinically relevant (impairment), depending on the degree of environmental risk the person is additionally exposed to. The psychosis proneness-persistence-impairment model considers genetic background factors impacting on a broadly distributed and transitory population expression of psychosis during development, poor prognosis of which, in terms of persistence and clinical need, is predicted by environmental exposure interacting with genetic risk.

/pdf/a-systematic-review-and-meta-analysis-of-the-psychosis-468eokeeyn.pdf

A systematic review and meta-analysis of the psychosis continuum: evidence for a psychosis proneness-persistence-impairment model of psychotic disorder

• An operational criteria checklist for psychotic illness and computer programs designed to be used in conjunction with it constitute the OPCRIT system. This provides a simple and reliable method of applying multiple operational diagnostic criteria in studies of psychotic illness. The development of the OPCRIT system and an assessment of reliability are described. Diagnostic agreement between three raters is excellent. Item-by-item agreement, although less good, still achieves reasonable reliability despite the problem of low base rates for some items.

https://jamanetwork.com/journals/PSYCH/articlepdf/495478/archpsyc_48_8_015.pdf

A Polydiagnostic Application of Operational Criteria in Studies of Psychotic Illness: Development and Reliability of the OPCRIT System

OBJECTIVE: The authors synthesize findings of previous studies implicating migration as a risk factor for the development of schizophrenia and provide a quantitative index of the associated effect size. METHOD: MEDLINE was searched for population-based incidence studies concerning migrants in English-language publications appearing between the years 1977 and 2003. Article bibliographies and an Australian database were cross-referenced. Studies were included if incidence reports provided numerators and denominators and if age correction was performed or could be performed by the authors. Relative risks for migrant groups were extracted or calculated for each study. Significant heterogeneity across studies indicated the need for a mixed-effects meta-analytic model. RESULTS: The mean weighted relative risk for developing schizophrenia among first-generation migrants (40 effect sizes) was 2.7 (95% confidence interval [CI]=2.3–3.2). A separate analysis performed for second-generation migrants (seven effect siz...

https://ajp.psychiatryonline.org/doi/pdf/10.1176/appi.ajp.162.1.12

Schizophrenia and migration: a meta-analysis and review.

Context Although differences in clinical characteristics exist between major depressive disorder (MDD) and bipolar disorder (BD), consistent structural brain abnormalities that distinguish the disorders have not been identified. Objectives To investigate structural brain changes in MDD using meta-analysis of primary studies; assess the effects of medication, demographic, and clinical variables; and compare the findings with those of a meta-analysis of studies on BD. Data Sources The MEDLINE, EMBASE, and PsycINFO databases were searched for studies from January 1, 1980, to February 2, 2010. Study Selection Two hundred twenty-five studies that used magnetic resonance imaging or x-ray computed tomography to compare brain structure in patients with MDD with that of controls were included in an online database, and 143 that measured common brain structures were selected for meta-analysis. Data Extraction Twenty-five variables, including demographic and clinical data, were extracted from each study, when available. For the meta-analysis, mean structure size and standard deviation were extracted for continuous variables, and the proportion of patients and controls with an abnormality in brain structure was extracted for categorical variables. Data Synthesis Compared with the structure of a healthy brain, MDD was associated with lateral ventricle enlargement; larger cerebrospinal fluid volume; and smaller volumes of the basal ganglia, thalamus, hippocampus, frontal lobe, orbitofrontal cortex, and gyrus rectus. Patients during depressive episodes had significantly smaller hippocampal volume than patients during remission. Compared with BD patients, those with MDD had reduced rates of deep white matter hyperintensities, increased corpus callosum cross-sectional area, and smaller hippocampus and basal ganglia. Both disorders were associated with increased lateral ventricle volume and increased rates of subcortical gray matter hyperintensities compared with healthy controls. Conclusions The meta-analyses revealed structural brain abnormalities in MDD that are distinct from those observed in BD. These findings may aid investigators attempting to discriminate mood disorders using structural magnetic resonance imaging data.

Structural neuroimaging studies in major depressive disorder. Meta-analysis and comparison with bipolar disorder

Stress-reactivity in psychosis: evidence for an affective pathway to psychosis

The aim of this study was to identify underlying dimensions of psychopathology in a cohort of patients with functional psychosis of recent onset, and to examine their prognostic value. Factor analysis of the psychopathological features of 166 consecutively admitted patients with functional psychosis of recent onset revealed seven psychopathological dimensions, which explained 63% of the variance. Five of these seven syndromes bore differential associations with subsequent treatment and illness course, independent of: (i) associations with DSM-III-R diagnosis; (ii) associations with other prognostic factors; and (iii) associations with the baseline values of outcome variables. The most striking associations were shown for an early and insidious onset syndrome with affective flattening, which predicted a more disabled course of illness on three of four outcome dimensions, and which was more common in males and unmarried individuals. A second syndrome, characterized by bizarre behaviour, inappropriate affect, catatonia, and poor rapport showed similar, slightly less striking, associations with illness course, as well as with poor pre-morbid social functioning. A third syndrome, characterized by positive psychotic symptoms was to a lesser degree associated with poorer outcome, whereas a fourth syndrome distinguished by manic symptomatology predicted a more benign illness course. A fifth syndrome identified by lack of insight predicted more time in hospital and admission under a section of the Mental Health Act during the follow-up period.A further finding was that dimensional representations of psychopathological features were considerably more useful than categorical representations (DSM-III-R and ICD-10) as predictors of illness course and treatment decisions.

Psychopathological syndromes in the functional psychoses: associations with course and outcome.

A case-control study was undertaken of volumetric computerized tomographic scan measures in 216 consecutive admissions for functional psychosis and 67 healthy community controls. Odds ratio analysis demonstrated significant linear trends in the association between increasing lateral and third ventricle volumes, and both RDC schizophrenia (N = 121) and schizo-affective disorder (N = 41); cases were consistently associated with larger volumes than controls. There was an association between larger third, but not lateral, ventricle size in affective psychoses (N = 54). These associations were statistically independent of intracranial volume, sex, social class and ethnicity, factors which were significantly associated with ventricular measures in the controls. There was no evidence of a threshold corresponding to the notion of normal versus enlarged ventricles. Within the schizophrenia group, there were no large or significant associations between ventricle dimensions and age at onset, duration of illness or pre-morbid social functioning. Neither obstetric complications nor a family history of schizophrenia or other psychiatric illness was associated with large ventricles in these cases.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0033291700029081

Cerebral ventricle dimensions as risk factors for schizophrenia and affective psychosis: an epidemiological approach to analysis.

CT scans were performed on 72 consecutive patients with a functional psychosis, and compared with 50 community controls. There was a specific difference in lateral ventricular area between these two groups but it accounted for only 11% of the variance in this measure. In contrast, racial and sexual differences in the ventricular-brain ratio (VBR) related to differences in intracranial area. It is argued that analysis of variance, using lateral ventricular area and intra-cranial area, is more informative than VBR in examining these structural changes in functional psychoses.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0033291700013222

The ventricular-brain ratio (VBR) in functional psychoses: the relationship of lateral ventricular and total intracranial area

BACKGROUND It has been suggested that the dimensions of cerebral ventricles are a risk factor for poor outcome in psychotic illness.

METHOD A cohort of 140 patients with functional psychoses of recent onset who had undergone CT scanning, were followed up for an average of 46 months and assessed on six dimensions of course and outcome of illness.

RESULTS Left and right sylvian fissure volumes and, to a lesser extent, third ventricular volume predicted negative symptoms and unemployment over the course of follow-up, the latter association being mediated by poor cognitive functioning. There was significant linear trend in risk over the distribution of sylvian fissure volumes in the cohort, and associations were especially evident in schizophrenic patients. No associations were found with global severity of illness, duration of hospital stay, homelessness, or affective symptoms.

CONCLUSIONS These findings support the notion that dimensions of the cerebral ventricles are a continuous risk factor for some measures of outcome in the functional psychoses.

M. Williams

Papers

Psychopathological syndromes in the functional psychoses: associations with course and outcome.

Cerebral ventricle dimensions as risk factors for schizophrenia and affective psychosis: an epidemiological approach to analysis.

The ventricular-brain ratio (VBR) in functional psychoses: the relationship of lateral ventricular and total intracranial area

Increased intracerebral cerebrospinal fluid spaces predict unemployment and negative symptoms in psychotic illness : a prospective study

Cerebral ventricle dimensions as risk factors for schizophrenia and affective psychosis: An epidemiological approach to analysis