Childhoodonset Schizophrenia

Childhood-onset schizophrenia (COS) is a rare psychotic disorder that in certain ways resembles a pervasive developmental disorder. Information on its prevalence is limited, in part because diagnostic criteria have changed considerably over the last decade (Volkmar and Tsatsanis, 2002). COS is almost certainly less prevalent than autism, however, and it is often diagnosed in the presence of an autistic spectrum disorder. Males and females seem equally likely to be affected. Premorbidly, COS is associated with a number of developmental delays, including disturbances in motor, general cognitive, linguistic, and social development (Jacobsen and Rapoport, 1998; Nicolson et al., 2000). Some evidence suggests that the premorbid and clinical courses of COS are more severe than those of later onset schizophrenia (Alaghband-Rad et al., 1995). Episodes are more acute, and on average are of longer duration, in younger compared with older children (Werry, 1996). The course of illness is highly variable.

Neurobiological Substrate. Knowledge of the neural systems involved in COS comes mostly from MRI studies in a small number of cohorts. These children have been consistently reported to have smaller brains and enlarged ventricles (Hendren et al., 2000; Sowell et al., 2000). One longitudinal study has reported a fourfold greater decrement in volume of the cortical gray matter during adolescence compared to healthy controls, most prominently in frontal and temporal regions (Rapoport et al., 1999). This reduction in cortical gray matter may contribute to a more rapid decrease in volumes of the total brain and hippocampus and a more rapid increase in ventricular volumes during adolescence. These age-related changes in the COS group slow by early adulthood (Jacobsen et al., 1998; Giedd et al., 1999). Reductions in volume of the right posterior superior temporal gyrus during this time have been reported to predict the severity of positive psychotic symptoms at follow-up (Jacobsen et al., 1998). Children with COS also have smaller thalamic and basal ganglia volumes when receiving typical but not atypical antipsychotic medications (Frazier et al., 1996; Hendren et al., 2000).

Other imaging modalities have detected lower levels of NAA (an index of neuronal viability) in the frontal lobes and hippocampus of children with COS (Bertolino et al., 1998; Sowell et al., 2000). The few existing PET studies have reported reduced frontal blood flow (Chabrol et al., 1986), reduced metabolism in middle and superior frontal regions, and increased inferior frontal metabolism in adolescents with COS (Jacobsen and Rapoport, 1997).



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