Negative symptoms are among the most robust clinical predictors of adaptive functioning in schizophrenia, particularly in residual or stabilized phases of the disorder. Executive functioning (EF) is also linked to adaptive functioning and partially overlaps with negative symptoms but may capture distinct self-regulatory processes involved in translating intentions into sustained real-world behavior. Most prior evidence relies on performance-based EF measures, which assess executive functioning under highly structured conditions. This study examined whether behavioral ratings of EF provide incremental explanatory value for adaptive functioning beyond negative symptoms in adults with residual-phase schizophrenia. Forty outpatients with residual-phase schizophrenia were assessed using the Life Skills Profile (LSP-39) to measure adaptive functioning, the Scale for the Assessment of Negative Symptoms (SANS), and the informant-report Dysexecutive Questionnaire (DEX). Hierarchical regression models were estimated to test the incremental contribution of behavioral EF beyond negative symptoms, using permutation-based tests for model improvement and bias-corrected and accelerated bootstrap confidence intervals. Behavioral EF ratings showed strong associations with global adaptive functioning and all functional domains. Negative symptoms were also significantly related to functioning, although associations were generally smaller. In hierarchical models, DEX scores accounted for a substantial and statistically significant proportion of additional variance in global adaptive functioning beyond negative symptoms. Similar incremental effects were observed across all LSP-39 subscales, with behavioral EF showing larger standardized coefficients than negative symptoms. These findings indicate that behavioral ratings of executive functioning provide nonredundant and clinically meaningful information about adaptive functioning in residual-phase schizophrenia.
Pérez-Flores et al. (Mon,) studied this question.