Language, motor and speed of processing deficits in adolescents with subclinical psychotic symptoms

Objectives: Neuropsychological impairment is a core feature of schizophrenia. Adolescents reporting subclinical psychotic symptoms are considered to be at greater risk of developing a psychotic illness later in life than adolescents who do not report such symptoms and, thus, may represent an at-risk group for further study. We wished to investigate neuropsychological functioning in early adolescence in relation to reports of psychotic symptoms.

Methods: Participants were recruited from local primary schools after a two-stage screening and parental consent process. In brief, 277 adolescents were screened and 37 attended for testing. Seventeen adolescents who were deemed to report 'definite' psychotic symptoms after clinical interview and 20 control adolescents underwent a clinical interview and a one-hour neuropsychological battery.

Results: Adolescents who report psychotic symptoms exhibited significant impairments in receptive language (as measured by the British Picture Vocabulary Scale), motor function (as measured by the Pegboard test) and executive function/speed of processing (as measured by the Trail-Making test). There were no significant differences between the groups on measures of attention, memory or expressive language, abstract reasoning or overall scholastic ability.

Conclusions: Taken together with the results from birth cohort, genetic high risk and prodromal studies, these findings are consistent with a neural inefficiency/disconnectivity hypothesis in those at risk for psychosis. These results highlight the need to investigate developmental brain circuits subserving language and motor function and processing speed and how these change over time in at-risk adolescents.