Effects of an Occupation-Based Group Occupational Therapy Intervention on Cognitive Functioning in Adults with Schizophrenia: A Randomized Controlled Trial

Background/Objectives: Cognitive impairment is a core feature of schizophrenia and is closely associated with everyday functioning and participation. This study examined the effects of a 12-week occupation-based group occupational therapy intervention on cognitive functioning in adults with schizophrenia. Methods: In this two-arm randomized controlled trial, 86 adults with schizophrenia were randomly allocated to an intervention group (n = 44) or a treatment-as-usual control group (n = 42). The intervention combined cognitive activation with everyday tasks, problem-solving, and social and creative activities. Co-primary outcomes were the Mini-Mental State Examination (MMSE), Addenbrooke’s Cognitive Examination III (ACE-III) total score, and Clock Drawing Test (CDT). Secondary outcomes included the Mini-Addenbrooke’s Cognitive Examination (M-ACE), ACE-III domains, and Trail Making Test (TMT) Parts A and B completion times and error counts, assessed at baseline and post-intervention. Group × time effects were examined using repeated-measures analysis of variance. Results: All 86 participants completed the post-intervention assessment and were included in the analysis. Compared with treatment as usual alone, the intervention was associated with significantly greater improvements in MMSE, ACE-III total, M-ACE, TMT Part A completion time, and the ACE-III language and visuospatial domains. Partial η2 values ranged from 0.17 to 0.43, with the largest effect observed for the ACE-III total score. Conclusions: Adding occupation-based group occupational therapy to usual care may improve global and domain-specific cognitive test performance in adults with schizophrenia. Further research should determine whether these changes are maintained and translate into everyday occupational performance and participation. This trial was retrospectively registered with ISRCTN (ISRCTN43725423).