Performance of schizophrenia patients on time-, event-, and activity-based prospective memory tasks.

The present study aimed to determine whether individuals with long-term schizophrenia have impaired prospective memory (PM), the ability to remember to perform intended actions in the future. Three PM tasks (time-, event-, and activity-based) were administered to 60 schizophrenia patients and 60 matched controls. Patients performed significantly more poorly than controls on all three tasks. The between-group difference was disproportionately larger on the time-based task, a task that required a prefrontal lobe process called self-initiated retrieval. To examine the relationship between PM and prefrontal lobe functions, subjects were also administered the Design Fluency Test (DFT), the Tower of London (TOL), and the Wisconsin Card Sorting Test (WCST). For patients, performance on the event-based task was found to correlate significantly with performance on the DFT, and performance on the time-based task was found to correlate significantly with performance on the TOL. Results of this study support the importance and contribution of prefrontal lobe processes in prospective remembering and have implications for the assessment and treatment of individuals with schizophrenia.