Prospective memory (PM), unlike traditional “retrospective” memory, involves someone’s ability to remember to carry out a delayed intention in the future, and is typically classified into time-based (intended actions are appropriately carried out at a particular moment) and event-based (intended actions are appropriately carried out at the occurrence of a particular event). PM ability has been consistently demonstrated in people with schizophrenia at different stages of the illness. The studies about PM were limited to the cross-section design and it is still unclear how the PM impairments proceed throughout the first onset of the illness up to the later stages of the illness.
Dr. CHAN Raymond (the senior author of the study) from the Institute of Psychology of Chinese Academy of Sciences and Dr. CHEUNG Eric from Hong Kong Castle Peak Hospital conducted a one-year prospective longitudinal study to examine the trajectory changes of PM impairments in people who received their first clinical diagnosis of schizophrenia.
Researchers recruited 58 individuals with first-episode schizophrenia and 37 healthy individuals who were matched in terms of demographics and intelligence with the patient group. They administered computerized PM tasks to both the people with schizophrenia and controls at baseline. People with schizophrenia were followed up at the 6-month interval up to 12 months after the onset of the illness.
Their findings showed that people with schizophrenia showed a gradual improvement in both time- and event-based PM 12months after illness onset. However, deficit in time-based PM persisted and was relatively stable. Interestingly, PM functions were not associated with clinical symptoms at baseline assessment but an association between time-based PM and PANSS positive and general symptoms emerged 12 months after the onset of the illness.
These findings provide additional evidence of the longitudinal stability of PM deficit to the growing body of literature which supports that PM deficit may be a putative neuropsychological marker for schizophrenia. Drs. CHAN and CHEUNG will continue to collaborate to examine the trajectory changes of PM performances in people with first-onset schizophrenia up to a 4-year outcome. Moreover, they are going to examine the underlying structural and functional connectivity changes associated with the course of the illness.
This study was supported by grants from the National Science Foundation of China, the Key Laboratory of Mental Health, Institute of Psychology of Chinese Academy of Sciences, and the Philip KH Wong Foundation.
The paper is now available online in Schizophrenia Research.
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