Assessing Clinically Significant Cognitive Impairment Using the NIH Toolbox in Individuals with Co-occurring Serious Mental Illness and Alcohol Use Disorder.

OBJECTIVE: Serious mental illnesses (SMI) and alcohol use disorder (AUD) co-occurrence (SMI-AUD) is common, yet little is known about the prevalence and risk factors of cognitive impairment for this population. We used the National Institutes of Health (NIH) Toolbox to identify clinically significant cognitive impairment (CSCI), describe the cognitive profile, and investigate whether psychiatric and AUD severity measures are associated with CSCI in individuals with SMI-AUD. METHODS: CSCI was defined as 2 or more fully corrected fluid subtest T scores below a set threshold based on an individual's crystalized composite score. Psychiatric severity measures included the Structured Clinical Interview for DSM-V (SCID-5) for SMI diagnosis and the Positive and Negative Syndrome Scale. AUD severity measures included the SCID-5 for AUD symptom severity score, years of alcohol use, and urine ethyl glucuronide levels. A multivariable logistic regression was used to investigate the adjusted effects of each variable on the probability of CSCI. RESULTS: Forty-one percent (N = 55/135) of our sample had CSCI compared with the base rate of 15% from the NIH Toolbox normative sample. Subtests measuring executive function most frequently contributed to meeting criteria for CSCI (Flanker and Dimensional Change Card Sort). A history of head injury ( P = 0.033), increased AUD symptom severity score ( P = 0.007) and increased negative symptom severity score ( P = 0.027) were associated with CSCI. CONCLUSIONS: Cognition should be considered in the treatment of people with SMI-AUD, particularly in those with history of brain injury, higher AUD symptom severity, and/or negative symptom severity.