Executive dysfunction in first-episode schizophrenia and relationship to duration of untreated psychosis: the West London Study.

Background: Many studies have demonstrated early generalised cognitive impairment in schizophrenia.

Aims: To examine executive function in first-episode schizophrenia, characterise the nature of the impairment and specify any relationships with symptoms and duration of untreated psychosis (DUP).

Method: Patients (n = 136) and normal controls (n = 81) were assessed with the Cambridge Automated Neuropsychological Test Battery, National Adult Reading Test IQ, and Scales for the Assessment of Positive and Negative Symptoms.

Results: Memory and executive impairments in patients were independent of IQ level. Spatial working memory was impaired because of inadequate strategy use. On a planning task, patients showed reduced planning times and suboptimal problem-solving. On an attentional set-shifting task, 75% of patients were able to perform an extra-dimensional shift thought to be a core attribute of prefrontal cortex function. Those who failed had significantly longer DUP.

Conclusions: Prefrontal cortex function deteriorates at the onset of psychosis and continues to worsen over time.