Objective: To examine the effectiveness of quetiapine versus conventional antipsychotics in improving cognitive and functional outcomes.

Method: Forty stable outpatients with DSM-IV schizophrenia treated in public outpatient clinics were randomly assigned to continue taking conventional antipsychotic medications or switch to quetiapine for 6 months, beginning September 1998 and ending July 2000. Neurocognitive and functional measures were obtained at study entry, 3 months, and 6 months by raters blinded to treatment. Group differences were examined using repeated-measures analyses of covariance for mixed models.

Results: The mean (SD) dose of conventional antipsychotics in chlorpromazine equivalents was 348.00 (348.28) mg/day; the mean (SD) dose of quetiapine was 319.25 (142.55) mg/day. A cognitive function summary score improved in the quetiapine group relative to the group treated with conventional antipsychotics over the 6-month period (F = 5.80, df = 1,28.9; p < .023). Patients taking quetiapine did better with respect to both verbal fluency (initiation) and verbal memory. There were also statistically significant group differences with respect to quality of life favoring the quetiapine group (F = 4.87, df = 1,29; p < .04). Differences were not found with respect to adaptive functioning.

Conclusion: Quetiapine improved cognition relative to conventional agents. After 6 months, groups differed by more than 1 standard deviation when baseline cognitive functioning was taken into account. No group differences were found with respect to improvements in community functioning. Improvements in adaptive functioning may lag behind improvements in cognition. Psychosocial programming may be necessary to translate gains in cognition into improvements in adaptive functioning.