Further clarification of the nature of prospective memory impairment in schizophrenia

Abstract

Memory impairment is a core deficit in schizophrenia, previous studies have focused on retrospective memory, and several studies have found prospective memory deficit in schizophrenia, the nature of this deficit is yet to be fully known. Prospective memory refers to the ability to execute a delayed intention, and it includes the following stages: intention formation; intention maintenance; cue detection and intention retrieval; intention execution. The present study aimed to further clarify the nature of prospective memory impairment in schizophrenia. Fifty-four patients with schizophrenia and 54 age, education, IQ and executive function matched healthy controls participated the study, they completed time-, event-, and activitybased prospective memory tasks and a set of neurocognitive tests, ie, working memory tests (Chinese Letter-Number Span, N-back), verbal and visual memory tests. Patients with schizophrenia performed worse in all time- (P < .001), event- (P < .01) and activity-based (P < .001) prospective memory tasks than healthy controls. Correlation analysis found that prospective memory correlated significantly with other cognitive functions. Patients still performed poorer even after controlling other cognitive functions (working memory, verbal memory, visual memory and executive functions). Results also found patients with schizophrenia did not perform poorer in recalling task requirements after finishing the prospective memory tasks, so the intention formation and intention maintenance stages maybe relatively intact in schizophrenia, and patients were mainly impaired in cue detection and intention retrieval stage. Prospective memory is a primary not secondary deficit in schizophrenia. Prospective memory deficit mainly occur in cue detection and intention retrieval stage.