Abstract
BackgroundChildhood adversities such as childhood abuse, bullying victimisation, and parental separation have been found to be associated with many psychiatric illnesses, including psychosis. A large body of research has been conducted on individuals at ultra-high risk (UHR) for psychosis, or clinical high risk (CHR) for psychosis. This review aims to quantitatively summarise (i) the associations between childhood adversities and the UHR state, and (ii) how these adversities may be linked with a higher risk of transition to psychosis (TTP).MethodsWe conducted systematic searches based on PubMed, EMBASE, and PsycINFO databases. We adopted search terms aimed at retrieving studies related to: (1) populations which were at UHR of psychosis, (2) exposure to childhood adversities, and (3) schizophrenia. Studies were eligible as long as they reported information on any form of childhood adversities and recruited participants at UHR of psychosis. Studies that only investigated the level of psychotic symptoms in a cohort or among schizophrenia patients were excluded.Whenever possible, we conducted meta-analyses to compare, across UHR and healthy individuals: (a) the levels of childhood trauma exposure, (b) childhood bullying victimisation, and (c) parental separation or loss. We conducted a second set of meta-analyses to investigate the effect of childhood trauma on TTP. Whenever allowed by provision of detailed information, we also conducted separate meta-analytic computations for each reported subtype of childhood adversity and trauma. All analyses were conducted in Review Manager 5.3, using inverse variance or Mantel-Haenszel methods (random effects model).ResultsThe systematic searches yielded 13 case-control, cross-sectional, and prospective studies from 27 publications, which recorded exposure to childhood adversities among UHR individuals: five of these studies employed longitudinal designs to investigate the conversion rate among UHR. Meta-analytic calculations revealed that, as compared to healthy controls, UHR individuals reported more severe childhood trauma (Random effects Hedges’ g = 1.38; 95% CI: 0.92–1.84, Z = 5.92, p < .001), were 5.5 times and 2.5 times more likely to report emotional abuse (OR = 5.54, 95% CI = 1.13–27.20, p = .03) and physical abuse (OR = 2.53, 95% CI = 0.73 - 8.76, p = .14) respectively. UHR individuals were 3.1 times as likely to report bullying victimisation (OR = 3.09, 95% CI = 2.23 - 4.30; Z = 6.72, p < .001). However, childhood trauma exposure in general was not significantly associated with psychotic conversion (HR = 1.01, 95% CI: 0.99 - 1.03; Z = 1.51, p = .13), suggesting perhaps that this risk is either mediated by other risk factors or that most specific traumatic experiences may contribute to an enhanced risk of conversion among UHR individuals.DiscussionTo date, this is the first meta-analysis that quantitatively summarises the associations between childhood adversities and TTP, and between specific abuse subtypes and the UHR state or TPP. Overall, our findings support the association between childhood adversities (trauma and bullying) and the UHR state; however, these adversities alone may not be sufficient to cause a UHR individual to develop frank psychosis. Most studies did not adjust for potentially confounding variables such as cannabis use, gender, education level, age, comorbid psychiatric disorders and other unmeasured variables such as socioeconomic status, urbanicity, genetic risk, and PTSD symptoms. The current review supports the need to screen for childhood adversities among the UHR population and to provide treatment accordingly, which may improve patients’ engagement with their treatments and result in better clinical outcomes.
Highlights
This study characterizes the age of onset of schizophrenia spectrum disorders and summarizes findings regarding a range of clinical and social outcomes, cognition, brain structure, and mortality
There has been increasing concern about potentially causal effects of tobacco use on psychosis, but epidemiological studies have been less robust in attempts to minimise effects of confounding than studies of cannabis use have been
Our findings indicate that whilst individuals who use either cannabis or cigarettes during adolescence have an increased risk of developing subsequent psychotic experiences, the epidemiological evidence for this being causal is substantively more robust for cannabis than it is for tobacco
Summary
Recent incidence estimates from population-based health administrative data in Ontario suggest an incidence rate of non-affective psychosis of 55.6 per 100,000 person-years in the general population. Early psychosis intervention (EPI) programs across the province estimate that the treated incidence of first-episode psychosis is in the range of 12 to 13 per 100,000 per year, which corresponds to frequently cited estimates of the incidence of schizophrenia. This discrepancy between population-based estimates of incidence and the treated incidence reported by EPI programs suggests that there may be additional cases of psychotic disorder receiving services elsewhere in the health care system. Our objective was to estimate the incidence of non-affective psychosis in the catchment area of an EPI program, and compare this estimate to the EPI-treated incidence of psychotic disorder. Using admission ratios from the EPI program (# admitted/# referred), we correct our population-based incidence estimate to yield an estimated “true incidence” of non-affective psychosis
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