Background: Rates of cardiovascular disease and stroke are elevated in Native Americans, and a greater propensity to develop vascular cognitive impairment (VCI) rather than Alzheimer-type dementia has been inferred, supporting a need for further research in VCI in this population. We determined rates and patterns of memory loss among Native American veterans with multiple vascular risk factors.
Methods: Native American veterans ≥50 years old with ≥2 vascular risk factors, including smoking history, hyperlipidemia, diabetes, coronary artery disease, or peripheral arterial disease, were recruited between September 2015 and May 2016. The Montreal Cognitive Assessment (MoCA) and the Beck Depression Inventory-II were used to screen for cognitive impairment and depression. Patients with MoCA scores <26 were referred for imaging studies, memory loss serology, neuropsychiatric testing and clinical assessment by a memory loss physician. Final cognitive status was assigned by blinded adjudication.
Results: We recruited 60 Native Americans aged 50-86 (mean±SD: 64±7.1 years); 90% were male, 95% had at least high-school education, and 69% had some college or advanced degrees. Risk factors included hypertension (92%), hyperlipidemia (88%), diabetes (47%), and prior/current smoking (78%). Eight (13%) with severe depression were excluded, leaving 23/51 with abnormal MoCA scores (44%, 95%CI 30%-59%). All with cognitive impairment were male compared to 83% among non-impaired subjects (p=0.059). Fifteen completed additional evaluation for memory loss, including 4/15 with normal MoCA scores who requested evaluation based on symptoms. Results were adjudicated as normal (4), or as having non-amnestic MCI (4), vascular MCI (5), and vascular dementia (2). MoCA correctly identified cognitive status in 86% (Kappa 0.66, 95%CI 0.23-1.00).
Conclusions: Native American veterans have high rates of vascular cognitive impairment, which exceed rates of cognitive impairment documented in previously published older non-Native American cohorts. These results highlight the need for improved vascular risk reduction among Native American veterans. Further study is needed to identify ways to improve care in this underserved and understudied population.