Level and pattern of neuropsychological functioning in early-onset psychoses.

The present study aimed to compare the level and pattern of cognitive deficits in patients with early-onset psychoses with an age, gender and IQ matched control group. In order to ensure a representative sample of patients with psychoses, participants with an IQ of less than 70 were included. Forty-eight patients with an onset of psychoses before the age of 16, and 47 age, gender and IQ matched controls without psychoses were recruited. Psychotic symptomatology was assessed using the Schedules for Clinical Assessment to obtain DSM-IV and ICD-10 diagnoses. Positive and negative symptoms were assessed using the Positive and Negative Symptoms Scale. Levels of cognitive function were measured using a comprehensive neuropsychological battery. A pattern of specific impairments was not found, with few significant differences between the two cohorts. However both cohort groups performed lower than age derived norms. Therefore it appears that there are global cognitive deficits rather than specific deficits in early-onset psychoses when compared to normative data, in-line with conclusions of early-onset schizophrenia research, but patients did not have greater deficit than controls when matched on IQ, gender and age, even after excluding participants with IQ less than 70.