The number of American Indian and Alaska Native (AI/AN) people living with dementia is expected to increase 5-fold by 2060. Social determinants of health may explain disparities in the incidence of Alzheimer disease (AD) but remain largely overlooked. We examined the time trend of AD mortality rates and associations of the percentage of AI/ANs, density of primary care physicians and neurologists, area deprivation index, rurality, and Indian Health Service region with AD mortality in 646 purchased/referred care delivery area counties. AD mortality rates significantly increased over time. Counties with higher concentrations of AI/AN people had lower AD mortality. More deprived counties had 34% higher AD mortality compared with less deprived counties. AD mortality was 20% lower in nonmetro counties than in metro counties. Findings have implications for prioritizing areas where more resources for AD care, education, or outreach are needed.