Neuropsychological Functioning in Cognitively Normal, Older American Indians of the Southwestern United States.

Objective: There is a dearth of research on neuropsychological functioning and the validity of assessment measures in American Indian (AI) older adults. The present study sought to comprehensively examine neuropsychological functioning in cognitively normal AI older adults in the southwestern USA (i.e., Arizona).

Participants and methods: Ninety predominantly female participants (45 AIs and 45 non-Hispanic Whites) aged 44 years and older (mean age of mid-60s) were matched on age, decade, gender, and assessment battery. Participants were enrolled in the Arizona Alzheimer's Disease Center database. Data obtained included demographics, medical history, psychiatric variables, and raw neuropsychological scores. Analyses included ANCOVAs, chi-square, and stepwise multiple regression.

Results: AIs generally had lower performance across all neuropsychological measures compared with matched Whites, even after controlling for demographic variables. Performance between groups was most discrepant on several measures of global cognition, attention, executive functioning, and language, while performance was statistically comparable on measures of memory and visuospatial abilities. The AI group had higher proportions of diabetes and obesity, but results showed that higher cardiovascular risk was not predictive of lower cognitive performance with the exception of the Clinical Dementia Rating Scale-Sum of Boxes.

Conclusions: Findings suggest that older AIs perform lower on many neuropsychological measures compared with non-Hispanic Whites, even after controlling for demographic variables. This suggests that other factors, including language, culture, educational quality, overall health, socioeconomic status, and level of acculturation may be impacting test scores and need to be considered when assessing and diagnosing older AIs.