Childhood Adversity, Cannabis Use and Psychotic Experiences
Adversity, cannabis use and psychotic experiences: evidence of cumulative and synergistic effects (2014)
C. Morgan, U. Reininghaus, A. Reichenberg, S. Frissa, SELCoH study team, M. Hotopf and S. Hatch
There is robust evidence that childhood adversity is associated with an increased risk of psychosis. There is, however, little research on intervening factors that might increase or decrease risk following childhood adversity. This study aimed to investigate main effects of, and synergy between, childhood abuse and life events and cannabis use on odds of psychotic experiences.
How was the study conducted?
Data on psychotic experiences and childhood abuse, life events and cannabis use were collected from 1680 individuals as part of the South East London Community Health Study (SELCoH), a population-based household survey.
What did we find?
A number of notable findings emerged. First, in relation to main effects, there was strong evidence that exposure to abuse and other adversities (life events) over the life course and recent cannabis use were associated with a two- to fourfold increased odds of reporting psychotic experiences in the 12 months prior to assessment. In addition, we found strong evidence that the impact of life events was cumulative and strongest for recent events that involved an element of threat or intrusion. Second, there was strong evidence that childhood abuse was associated with an increased odds of later life events and cannabis use, and, consistent with our hypotheses, there was evidence for synergistic effects of abuse and both life events and (more tentatively, given P = 0.07) recent cannabis use on odds of psychotic experiences, such that the odds were greatest in those exposed to abuse and either life events or cannabis in the past year. Before considering these findings further, a number of methodological limitations need to be considered.
Our findings are consistent with the hypothesis that childhood abuse creates an enduring vulnerability to psychosis that is realised in the event of exposure to further stressors and risk factors.
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