Independent Association of Prospective Memory with Retrospective Memory and Intelligence in Schizophrenia: A Controlled Study

Prospective memory (PM) refers to the ability to remember to do something in the future. This study examined the relationship between three PM subtypes, and intelligence and retrospective memory (RM) in schizophrenia patients and healthy controls. The study sample comprised 110 schizophrenia patients and 110 healthy controls matched according to age, sex, and level of education. The patients' clinical condition was evaluated with the Brief Psychiatric Rating Scale. Time-, event-, and activity-based PM and RM (immediate and delayed Logical Memory subtests of the Wechsler Memory Scales-Revised), executive functioning (Design Fluency Test, Tower of London-4 disk, and Wisconsin Card Sorting Test), and intelligence (Raven's Progressive Matrices) tests were administered to all participants. Correlation analyses showed time- and event-based PM to be significantly associated with RM in both the patients and controls, but with intelligence only in the patients. After controlling for covariates, only time-based PM was associated with RM in the controls and only event-based PM with intelligence in the patients. In schizophrenia, PM deficit may arise from the impairments of the retrospective components of memory.