Researchers have found an increased risk of psychosis among individuals who were physically abused as children.
"The current findings support the notion that childhood physical abuse may be one experience that alters neurobiological development and increases the risk for a psychotic illness," say Mark Shevlin (University of Ulster at Magee College, Londonderry, UK) and colleagues.
The researchers assessed data from the National Comorbidity Survey to estimate the relationship between interpersonal trauma and the likelihood of psychosis in 5877 individuals aged between 15 and 54 years.
The traumatic experiences included rape, serious attack or assault, physical abuse as a child, neglect as a child, and sexual molestation.
Analysis showed that physical abuse was the only traumatic event that significantly predicted psychosis, increasing the risk 2.68 fold in affected individuals compared with those not physically abused as children.
Looking at the effects of trauma depending on gender, the researchers found that physical abuse still predicted psychosis, with an odds ratio of 3.45, compared with no physical abuse, but there was also a gender-by-rape interaction.
The effect of rape in predicting psychosis was statistically more significant for men than for women, with odds ratios of 5.8 and 4.0, respectively.
Shevlin and team note that the effect of trauma on psychosis risk was cumulative. They found that the risk of developing psychosis following one or two traumatic experience was 2.12 and 3.89 times higher than that for no trauma, and increased 7.96-fold following three or more such experiences.
While childhood physical abuse was the only significant predictor of psychosis, the team points out that there was significant homogeneity among the effects of all trauma variables. The odds ratio for all traumas, although lower than that for childhood physical abuse, was still statistically significant, at 1.80.
"The findings highlight the importance of evaluating interpersonal victimization experiences during clinical assessment to ensure comprehensive formulation of the patient's difficulties and appropriate treatment planning," the investigators conclude.