(Boston)—In a new NIH-supported study in the journal Alzheimer's & Dementia: The Journal of the Alzheimer's Association , researchers detected significant risk associations for vascular and Alzheimer’s dementias among American Indians for four previously-identified key risk factors: limited education, hypertension, social isolation, and depression.
Prior research published by the Lancet Commission found that 14 modifiable risk factors in early life, mid-life, or later life are collectively responsible for up to 45% of dementia cases in the general population. These 14 factors include: limited education, hearing loss, elevated low density lipoprotein cholesterol (LDL), depression, history of traumatic head or brain injury (TBI), physical inactivity, diabetes, smoking, hypertension, obesity, excess alcohol use, social isolation, exposure to air pollution and vision loss. This estimate of 45% is based on a concept called population attributable fraction (PAF), which represents the proportion of disease in the population that is attributable to the presence or absence of a particular factor. This concept is important because it helps to identify high-impact targets for public health prevention efforts to reduce the burden of dementia for all people.
In this new report, researchers validated the previous model for 10 of these 14 factors, finding only 4 of them to have statistically significant association in American Indian groups. The PAF for these 4 factors were: education 19%, hypertension 11%, social isolation 13%, and depression 60%; the researchers also noted that the depression finding might be a high estimate because depression can also be a symptom of dementia. Together these 4 factors might represent the highest potential impact for dementia prevention programs in Native American populations.
“Our results point to the need for careful consideration of exposures and tailored prevention programs across the life-course when assessing cognitive risk for Indigenous populations. Later-life factors (isolation, depression) are likely to provide efficient targets for community interventions, whereas public health programs designed to improve treatment and control of hypertension and cardiovascular conditions are critically needed to resolve persistent health inequities. Finally, structural improvements to educational systems, learning resources and skills training for rural communities may result in better life-course trajectories for all who live in those communities,” said corresponding author Astrid Suchy-Dicey, PhD, associate professor medicine at Boston University Chobanian & Avedisian School of Medicine.
The researchers also evaluated the pattern of these 10 dementia risk factors among older American Indians and compared the results to the previous reports from the Lancet Commission. They found that some risk factors were less common, some were more common, and some about the same for American Indians as for the general population. These findings suggest that American Indian populations may have a complex and unique pattern of contributing factors that increase risk of vascular and Alzheimer’s dementias. The authors point out that these differences are likely to stem from differences in socioeconomic environment, and that this work emphasizes the importance of including many groups when conducting population research, for the most valid understanding of health and disease in all peoples.
The researchers also pointed out that because of the high burden of some risk factors, this population may develop neurodegenerative (Alzheimer's) and vascular injury earlier in life, or with faster progression towards dementia. “Future research should evaluate risk in younger groups--perhaps as young as 35-45--in order to observe conversion from healthy to symptomatic, and thus evaluate risk with lower potential for bias due to selective survival,” said Suchy-Dicey.
This research was conducted among participants of the Strong Heart Study, a large cohort of American Indians aged 45-95 years residing in Tribal communities in the U.S. Southwest, Southern Plains, and Northern Plains. Individuals attended multiple examination visits from mid- to late-life, and were assessed cognitively. The researchers then used regression models to assess prevalence, relative risk, and PAF for dementia. Strong Heart Study research is conducted in collaboration with the participating Tribal communities using a community-participatory research model, which centers research participants and Tribes throughout the research process. More information about the Strong Heart Study research programs can be found on the NIH website, or at strongheartstudy.org.
Data/statistical analysis
People
Risk factors and population attributable fraction for dementia in American Indians: The Strong Heart Study
24-Aug-2026