Course of head growth from birth to adolescence across the psychosis spectrum.

BACKGROUND: Charting developmental abnormalities in future psychotic disorder could help identify pathogenic processes. Head circumference (HC) is a proxy for brain size. Studies of HC and its developmental trajectories in future psychotic disorder cases and across the psychosis spectrum are inconclusive. It is important to determine whether deviations in HC are specific or reflect a general growth disorder. METHODS: We used data from the Avon Longitudinal Study of Parents and Children (ALSPAC) to chart HC trajectories from birth to 15 years in individuals with operationally-defined psychotic disorder (N = 62), psychotic experiences (PE; N = 339) and controls (N = 3,527). We extracted total intracranial volume (TIV) from MRI data on a subset (N = 347) scanned at age 20. RESULTS: HC at birth, 7 and 15 years was correlated with TIV at age 20 (r's = 0.45-0.77). The psychotic disorder group had consistently smaller HC from birth through to adolescence (B = -0.26, p = 0.02). Females with PE had smaller HC across childhood and adolescence (B = -0.27, p = 0.016), while males with PE had consistently larger HC (B = 0.35, p = 0.023). The effects did not change when controlling for maternal and pregnancy-related characteristics but attenuated after controlling for height, except in males with PE. CONCLUSIONS: Deviations in head and hence brain size across the psychosis spectrum likely reflect a more general growth abnormality. Future studies should examine factors regulating growth during early life in relation to psychosis, including sex, to understand underlying mechanisms.