High rates of undiagnosed vascular cognitive impairment among American Indian veterans.

As data on prevalence and etiology of dementia in American Indians are limited, we sought to determine rates and patterns of memory loss among American Indian veterans with vascular risk factors. Sixty consecutive outpatient American Indian veterans with a mean age of 64 years (range 50-86), without prior dementia or mild cognitive impairment (MCI), and with ≥ 2 vascular risk factors were enrolled. 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 additional evaluation, including imaging, serology, and neuropsychological testing. Overall rates, types, and distribution of cognitive impairment were determined. Most prevalent vascular risk factors included hypertension (92%), hyperlipidemia (88%), diabetes (47%), and smoking (78%). Eight patients (13%) with severe depression were excluded, leaving 23/52 with abnormal MoCA scores (44%, 95%CI 30%-59%). Fifteen completed additional evaluation for memory loss, including four with normal MoCA scores who requested evaluation based on symptoms. Results were adjudicated as normal (4), non-amnestic MCI (4), vascular MCI (5), and vascular dementia (2). These results show that rates of undiagnosed cognitive impairment among American Indian veterans with vascular risk factors exceed rates previously published in non-American Indian cohorts. The most common etiology is vascular. Our findings support the need to improve vascular risk reduction in this understudied population.