Exploring the Relationship between Cognitive Performance, Performance-Based Functioning, and Everyday Functioning in...

Cognitive and functional impairments are core features of schizophrenia with considerable disease burden. However, the relationships between cognitive performance, functional capacity, and real-world functioning remain incompletely understood. This systematic review aimed to clarify the magnitude and nature of these interrelationships across primary research studies.

A systematic review (PROSPERO CRD42024532729) was conducted across MEDLINE, Embase, PsycINFO, and Cochrane Database. Eligible articles assessed cognitive performance, functional capacity, and real-world functioning in adults with schizophrenia using standard psychometric instruments, and reported quantitative relationships between ≥1 of these constructs. Due to substantial heterogeneity in study designs, outcome measures, and reported metrics, a narrative synthesis was performed.

Overall, 104 articles with unique datasets were included (88 observational, 16 interventional). The relationship between cognitive performance and functional capacity was the most studied (63/104 articles; 60.5%), with predominantly medium-to-large effect sizes. In contrast, associations between cognitive performance and real-world functioning were less frequently reported (43/104 articles, 41.3%) and largely small-to-medium, with only 2 large effect sizes identified. Associations between functional capacity and real-world functioning were variable (41/104 articles; 39.4%) and predominantly small-to-medium, with only 4 large effect sizes reported. Associations were less consistent when examined at the level of specific cognitive or functional domain.

This review highlights the central role of cognition in shaping functional abilities, while reinforcing the complexity of translating these gains into meaningful improvements in everyday functioning. A multimodal, person-centered approach is needed to effectively translate cognitive improvements into meaningful real-world outcomes in people with schizophrenia.