The Temporal Relationship Between Change in Cognition and Change in Adaptive Functioning in Schizophrenia: Implications for Therapies Focused on Improving Cognitive Deficits

Background: Neurocognitive deficits remain a core feature of schizophrenia. This has led to the development and refinement of therapies for schizophrenia that target improvements in cognition. Many of these therapies are prescribed with the assumption that improvements in cognition may translate to improvements in real-world functioning, yet the majority of studies assessing the relationship between neurocognition and functioning have been cross-sectional, failing to evaluate the relationship between change in these two domains. In this study, the relationship between change in cognition and change in functioning was assessed in the context of a psychosocial treatment trial. Methods: In the present study, 96 community-dwelling individuals diagnosed with schizophrenia or schizoaffective disorder were evaluated on measures of neurocognition and adaptive functioning at the beginning and on cessation, one year later, of computer-skills training or cognitive remediation therapy. The cross-sectional relationship between cognition and functioning and the amount of improvement or decline on these measures across the one-year treatment trial was assessed. A multiple linear regression analysis was used to assess the relationship between cognitive and functional change. Results: A cross-sectional relationship between baseline cognition (working memory, processing speed, attention, and verbal intelligence) and adaptive functioning was confirmed and significant improvement was observed on select measures of cognition as well. Improvements in working memory and processing speed predicted improvements in adaptive functioning, however only working memory was a specific predictor as premorbid verbal intelligence explained the relationship between improvements in processing speed and functioning. Conclusions: The observed relationship between neurocognitive and functional change in this study adds to a growing body of longitudinal studies reporting associations between select facets of cognition and functioning. Further studies clarifying the relationship between change in these two domains is crucial for validation of cognitive remediation therapies for schizophrenia that aim to improve functional outcome in patients by identifying cognition as a core treatment target.