Dementia Risk Among US Veterans Varies Significantly by Region

Dementia incidence among older veterans varies significantly across regions in the US, according to study findings published in JAMA Neurology.

To investigate geographic differences in dementia incidence among US veterans, researchers conducted a cohort study of veterans aged 65 years and older who obtained care at Veterans Health Administration medical centers from 1999 to 2021. Eligible participants had at least 1 visit during the 2-year period before their random selection date (baseline) and at least 1 follow-up visit. Individuals with prevalent dementia at baseline, missing zip codes, and no follow-up visit were excluded. The primary outcome was a dementia diagnosis. Poisson regression models were employed for statistical analysis.

Participants (N=1,268,599; mean age, 73.9 years; women, 2.0%; White, 86.1%)   included in the study had a mean follow-up time of 12.6 years. Individuals in the Southeast and South regions had lower educational attainment, and those in the Midwest and Rocky Mountains had a higher percentage of residents in small rural areas vs other regions.

Prevalence of diabetes was highest in the South (26.6%) and Southeast (26.5%), and lowest in the Rocky Mountains (21.3%). Hypertension prevalence was highest in the Southeast (72.3%) and lowest in the Rocky Mountains (61.5%) and Northwest (61.9%) regions.

Unadjusted dementia incidence (per 1000 person-years) for each region were as follows:

• Southeast: 14.0 (95% CI, 13.8-14.2)
• South: 13.1 (95% CI, 12.9-13.3)
• Rocky Mountains: 13.0 (95% CI, 12.7-13.3)
• Northwest: 12.9 (95%CI, 12.7-13.2)
• South Atlantic: 12.4 (95% CI, 12.3-12.6)
• Southwest: 12.3 (95% CI, 12.1-12.5)
• Midwest: 12.3 (95% CI, 12.1-12.5)
• Northeast: 12.0 (95% CI,11.8-12.1)
• Great Lakes: 11.9 (95% CI, 11.8-12.0)
• Mid-Atlantic: 11.2 (95% CI, 11.1-11.4)

After adjusting for demographics, the rate ratios (RR) for dementia incidence compared with the Mid-Atlantic region were:

• Southeast: RR, 1.25 (95% CI, 1.22-1.28)
• South: RR, 1.18 (95% CI, 1.15-1.20)
• Rocky Mountains: RR, 1.23 (95% CI, 1.20-1.26)
• Northwest: RR, 1.23 (95% CI, 1.20-1.27)
• South Atlantic: RR, 1.12 (95% CI, 1.10-1.14)
• Southwest: RR, 1.13 (95% CI, 1.11-1.15)
• Midwest: RR, 1.12 (95% CI, 1.09-1.14)
• Northeast: RR, 1.07 (95% CI, 1.05-1.09)
• Great Lakes: RR, 1.07 (95% CI, 1.05-1.09)

Study limitations included a small study population, lack of generalizability, and inability to make inferences on time period of residency or participant migration patterns.

“By identifying areas with the highest incidence rates, resources can be better allocated and targeted interventions designed to mitigate the impact of dementia on vulnerable populations,” the researchers concluded.

One study author declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.