Chapter 9

Post-traumatic stress disorder and schizophrenia

PTSD is defined as the occurrence of symptoms of greater than one month duration, including re-experiencing distressing aspects of the trauma, hyper-arousal, avoidance of trauma reminders, sleep disturbances, and negative cognitions and mood, that typically develop after experiencing or witnessing an event or events that involve actual or threatened death or injury, of significant physical integrity to self or others (Association 2013) (see Box 9.1). There is growing evidence that people with a severe mental illness are more vulnerable to PTSD due to increased risk of childhood and adulthood trauma and the experience of psychosis itself. Traumatic events themselves are highly prevalent in severe mental illness, with up to 90% of subjects reporting trauma (Lommen and Restifo 2009).

In cross-sectional studies, up to 30% of patients with schizophrenia meet diagnostic criteria for PTSD, albeit the aggregated risk estimates across studies are more in the order of 12% (see Chapter 2). An 18-month follow-up of first episode patients reported 31% developing PTSD, and substance abuse is a further risk association, such that nearly two-thirds of patients with schizophrenia and comorbid substance misuse have been reported to also meet criteria for PTSD (Grubaugh et al. 2011; Jackson et al. 2009; Seow et al. 2016).

Causation

Shared risk factors and mechanisms

Adverse events in childhood and early adulthood increase the risk of psychosis (see Box 9.2). Parental loss, bullying, and childhood abuse occur more frequently than chance in the lives of people with psychotic disorders. These traumatic events may be acting on an underlying (genomic or epigenetic) vulnerability, triggering psychosis. Indeed, one current mechanistic hypothesis centres on maternal immune activation, whereby early pro-inflammatory insult (maternal stress, viral exposure, etc.) leads to a heighted inflammatory response when a second trigger occurs—the second trigger being an environmental challenge, including traumatic events. Immune activation, insufficient oxidative defence, and/or secondary glutamatergic and striatal dopaminergic changes are then secondary effects (Upthegrove and Khandaker 2019). It is parsimonious that those who are more vulnerable to psychosis may also be more likely to experience early trauma (Seow et al. 2016). Thus, the same events that can predispose to schizophrenia could lead to the development of PTSD in addition to psychosis.

Related posts:

Generalized anxiety and panic disorder in schizophrenia Personality disorders and schizophrenia Social anxiety disorder and schizophrenia Schizophrenia and obsessive compulsive disorder Understanding and assessing substance use in schizophrenia Why are psychiatric comorbidities so common in schizophrenia and why are they so often missed in clinical practice?

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