Neurocognition, functional capacity, and functional outcomes: The cost of inexperience

Background: Neurocognitive impairments are the strongest predictor of functional deficits in schizophrenia, but adaptive (i.e., functional) capacity, typically measured with performance-based assessments, yields an objective index of current abilities, whereas real-world functional performance relies on observations of community activity. However, limited experiences in the community may limit the acquisition, retention, or expression of these skills. Methods: We examined the frequency of engagement in behaviors that are assessed in the current "gold standard" in person functional capacity assessment. The UCSD Performance-Based Skills Assessment (i.e., UPSA) examines skills associated with recreational engagement, handling money, scheduling appointments, and navigating public transportation. We used neurocognition, experience, and UPSA performance as predictors of the relationships among cognition and real-world functioning variables. Results: Neurocognition was a significant correlate of UPSA scores regardless of whether it was forced into the model before or after prior experience, whereas experience was only a significant predictor of UPSA scores when entered before neurocognition. Further, functional capacity, neurocognition, and experience were significant predictors of real-world outcomes and experience remained a significant predictor regardless of the order it was entered into the model. Conclusions: The amount of current experience with functional tasks is not a rate-limiter of the relationships between neurocognition and functional capacity but does account for some previously unexplained variance in the functional capacity-everyday functioning relationship. These findings underscore the importance of neurocognitive deficits as they relate to functional capacity in schizophrenia, and suggest an incremental functional cost of limited experience with independent living.