Brief report: A randomized controlled trial of a compensatory cognitive training to improve prospective memory performance in people with schizophrenia or depression

People with schizophrenia or depression have prospective memory (PM) deficits, which affect their daily living. Given the paucity of research into training to correct PM deficits, we subjected a group of participants to a Chinese version of the PM module of the Cognitive Compensatory Training (CCT-C-PM) intervention to study its effect on their PM performance. Specifically, we independently randomized two diagnostic cohorts (schizophrenia and depression) into control groups (occupational therapy only) or experimental groups (CCT-C-PM and occupational therapy). The schizophrenia cohort had 17 participants in its control group and 23 participants in its experimental group. The depression cohort had 10 participants in its control group and 12 participants in its experimental group. The sociodemographic information of the participants was collected. Their symptoms and PM performances were measured at baseline and after treatment (after the completion of the CCT-C-PM intervention in the experimental group and the same timeframe in the control group). The treatment effects were examined by a repeated measure analysis of variance/analysis of covariance and a post hoc Scheffé test. The effect sizes (Cohen's d) of treatments against the controls were also calculated. There was no difference between the experimental and control groups in either cohort in terms of sociodemographic data, symptoms, and PM measures at baseline. The sex combination differed across the groups in the depression cohort. We found that the CCT-C-PM improved PM, especially event-based PM, for which large effect sizes were seen. The effect on time-based PM was unclear and requires future study. Our findings suggest that the CCT-C-PM is a viable training method for improving PM.