This post is by Rachel Upthegrove, a Senior Clinical Lecturer in Psychiatry at the University of Birmingham.
Childhood trauma has been in focus as an environmental risk factor for psychosis, with some authors proposing a causal role with significant lack of recognition and underreporting of childhood trauma in those who treat patients with psychosis. Mechanisms proposed include a process of hypervigilance leading to persecutory ideation and enhanced 'threat to self' networks. However, often studies have looked at small clinical samples or alternatively adopted a large population based approach measuring self-reporting psychotic-like experiences (assessed for example by being asked to rate: 'People are trying to upset me' and 'People communicate about me in subtle way'). This is open to challenge - these measures may be very sensitive but are not necessary specific.
Many children throughout the world experience childhood adversity, and this unfortunate fact has been with human society throughout time and across cultures. Children remain subject to physical neglect, disease, illness, want, hardship, and exploitation. The challenge therefore may be to explain why indeed more children do not go one to develop psychosis, rather than any other type of mental disorder or no disorder at all. In order to begin this exploration we need to stop and think about what we mean by childhood trauma, and what is meant by psychosis.
The Bipolar Disorder Research Network is one of the world's largest studies of Bipolar Disorder, run by the Mood Disorders Research Group based at Cardiff University and the University of Birmingham. We aim to investigate how genetic and environmental factors interact to increase susceptibility to Bipolar Disorder. Patients with Bipolar disorder, also known as manic depression, have severe episodes of mood disturbance that are sustained, intense, and interfere with an individual’s ability to function. The prevalence of Bipolar Disorder is around 1% of the population, roughly evenly spread across the world.
For some people with Bipolar Disorder, mood episodes are accompanied by psychotic symptoms such as delusions and hallucinations. As part of the BDRN’s program of research, we investigated the association between childhood events and psychosis, and in particular looking at symptoms driven by dysregulation of mood or with a persecutory content using data from 2019 participants who had completed an extensive 1:1 structured clinical interview and case note review. Childhood events were coded as thirteen different categories of event including death, separation or divorce of a parent, exclusion from school, and childhood abuse (further grouped into emotional, physical, or sexual abuse) (Upthegrove et al 2015).
Unlike some previous studies with our large sample and detailed interviews, we found no relationship between childhood events, or childhood abuse, and psychosis per se. Childhood events were not associated with an increased risk of persecutory or other delusions. However significant associations were found between childhood abuse and auditory and visual hallucinations, strongest between child sexual abuse and mood congruent or abusive voices. These relationships remained significant even after controlling for lifetime-ever cannabis misuse.
Our results offer both a confirmation and challenge to the argument for childhood trauma being seen as risk (or indeed causal) factor for psychosis. Child sexual abuse has a significant association with hallucinations. One prominent theory of hallucinations is that they arise from aberrant memory activation and internal monitoring. This model postulates a failure of inhibition of recall and unintended memory activation, with the resulting intrusive memories arising 'out of context' and with a perception of 'otherness' to these events. The equivocation between inner and outer events is seen as a defensive manoeuvre to avoid reliving the traumatic experience itself or acknowledging it as having happened. Hippocampal hyper-activation is also apparent during hallucinations, supporting the idea of voices as traumatic aberrant memory or an intrusive, dissociative experience. However, our results also suggest that that the pathways leading to psychotic symptoms differ and are complex, with delusions and non-hallucinatory symptoms being influenced less by childhood or early environmental experience.