Cognitive changes in patients with acute phase psychosis--effects of illicit drug use

Illicit drug use may influence cognition in non-affective psychosis. Previous studies have shown better cognition in psychosis with illicit drug use as compared to psychosis only. Possibly, illicit drug using patients have more transient drug-related cognitive deficits. Thus, the aim of the present study was to examine cognitive change the first weeks after admission to a psychiatric emergency ward, expecting more cognitive improvement at follow-up in the illicit drug group as compared to psychosis only. Patients with acute non-affective psychosis with (26%) and without illicit drug use were examined at baseline (n=123) and follow-up (n=67), with alternative forms of the Repeatable Battery for the Assessment of Neuropsychological Status. Latent Growth Curve models, controlling for cognition at baseline and age differences between the groups, were used to analyze cognitive change. The illicit drug using patients showed the largest improvement in cognition, especially among the youngest patients. Younger patients with non-affective psychosis and illicit drug use showed more cognitive improvement the first weeks after acute psychosis as compared to psychosis only. This suggests that the illicit drug users constitute a sub-group with less stable cognitive deficits and less cognitive vulnerability.