Abstract
BACKGROUND: Childhood maltreatment and trauma (CMT) increase the risk for schizophrenia spectrum disorders (SSDs) and the severity of psychosis symptoms. Few studies have considered the possible influence of parental mental health on the relationship between CMT and symptoms of psychosis. Possibly, parental mental health problems (MHP) confound this relationship by increasing both the genetic vulnerability for psychosis and the potential for sub-optimal childhood environments. The aim was to examine the potential influence of parental MHP on the relationship between CMT and symptoms of psychosis. We hypothesized a positive and dose-dependent association between overall CMT and symptoms of psychosis not moderated by parental MHP. METHODS: Patients with SSDs (N = 133) from the Bergen-Stavanger-Innsbruck-Trondheim (BeStInTro) study were included and assessed for CMT by the Childhood Trauma Questionnaire - Short Form, psychosis symptoms by The Positive and Negative Syndrome Scale and parental mental health by means of focused patient interviews. RESULTS: Regression analyses showed a dose-response relationship between CMT and overall psychosis symptom severity and negative symptom severity, further supported by t-tests showing that SSD patients with CMT showed more psychosis symptoms compared to SSD patients with no CMT. Multiple regression analysis with interaction term showed that the association between CMT and psychosis symptom severity was independent, and not moderated, by parental MHP. CONCLUSION: A dose-dependent relationship between CMT and psychosis symptoms emerged, not moderated by parental MHP, suggesting that CMT has an independent and true effect on psychosis symptoms.