Relationships among functional capacity, cognition, and naturalistic skill performance in people with serious mental illness.

There has been increasing interest in understanding real-world outcomes for individuals with serious mental illnesses (SMI). This study examined domain-specific skill knowledge, functional capacity, and neurocognition as predictors of naturalistic grocery shopping skill performance in forty-eight individuals with SMI. Participants completed measures of skill knowledge and general functional capacity (UCSD Performance-Based Skill Assessment - brief) as well as measures of neurocognition and symptoms. The Test of Grocery-Shopping Skills (TOGSS) assessed naturalistic shopping. TOGSS was significantly correlated with functional capacity, shopping skill knowledge, and neurocognition, but not symptoms. Multiple regression analysis was conducted with variables entered in 2 blocks. Skill knowledge and functional capacity were entered in block 1. Neurocognitive measures were entered in block 2 using forward entry. Skill knowledge was not a significant predictor of TOGSS when accounting for functional capacity and neurocognition. Functional capacity predicted TOGSS over and above skill knowledge and remained significant after accounting for the effects of neurocognition. Our findings indicate that functional capacity was associated with skill assessment under naturalistic conditions. Further, there was some, but not complete, overlap between neurocognitive and functional capacity predictors of naturalistic skill performance. Further development of naturalistic assessments may hold promise for interventions targeting real-world function.