Meta-analysis of prospective memory in schizophrenia: nature, extent, and correlates.

Prospective memory (PM) is the ability to remember to carry out an intended action in the future and it is an important function for everyday living. Studies have found that the neural basis of PM is located mainly in the prefrontal lobes (particularly in Brodmann Area 10) and patients with schizophrenia have functional deficits in this area. The present study provided a meta-analytic review of PM performances in patients with schizophrenia in 11 studies. A total of 485 patients with schizophrenia and 409 controls were included. Results showed that patients with schizophrenia exhibited impairments in all time- (d=-1.33), event- (d=-0.827), and activity-based (d=-0.729) PM, with time-based PM more impaired than event-based PM. In addition, PM was found to be significantly correlated with negative symptoms (r=-0.18), general psychopathology (r=-0.168), medication dosage (r=-0.119), duration of illness (r=-0.131), age (r=-0.23), education (r=0.249), IQ (r=0.439) and premorbid IQ (r=0.356). It has theoretical and clinical implications. Theoretically, the results indicate time-based PM involves more initiation than event-based PM. Clinically, the results indicate patients on high dose of antipsychotic medication and with long duration of illness need special attention from care givers for PM problems.