Psychiatric disorders in child and adolescent offspring of patients with schizophrenia and bipolar disorder: A controlled study.

BACKGROUND Early clinical manifestations predating schizophrenia (SZ) and bipolar disorder (BP) have not been fully characterized. Child offspring studies are a valuable opportunity to study the natural history of the illness from its earliest stages. However, there is limited evidence assessing young offspring of SZ and BP simultaneously. We set out to assess rates of psychiatric disorders in child and adolescent offspring of SZ and BP, relative to offspring of community controls, so as to characterize the early phenotype of the disorders comparatively. METHODS SZ and BP parents with offspring aged 7-17years were recruited through adult mental health services of two tertiary hospitals. Community control (CC) parents were recruited from the same geographical area. Ninety BP-offspring, 41 SZ-offspring and 107 CC-offspring were assessed using the K-SADS-PL by child psychiatrists blinded to parental status. Differences in prevalence of psychiatric disorders between groups were adjusted for confounders and for sibling correlation using generalised estimating equations. RESULTS We found a gradient of clinical severity and social disadvantage between SZ, BP and CC-offspring. After adjusting for socio-demographic confounders, SZ and BP-offspring presented higher rates of attention deficit hyperactivity disorder (ADHD) than CC-offspring. ADHD was more prevalent in SZ-offspring than BP-offspring, and BP-offspring presented a higher prevalence of depression than CC-offspring. CONCLUSIONS The higher rates of ADHD in SZ-offspring suggest that abnormal neurodevelopmental processes may exert a stronger influence in SZ than BP. Follow-up of these children will help elucidate the role of ADHD and depression phenotypes in predicting future transition to SZ or BP.