Hypertension, Diabetes, High BMI All Early Life Risk Factors for Dementia

Maria C. Carrillo, PhD

Results from 2 studies presented virtually at the Alzheimer’s Association International Conference (AAIC) 2020 annual meeting suggest that hypertension, diabetes, a combination of multiple cardiovascular risk factors, and high body mass index (BMI) are all early life risk factors for developing dementia.^1,2

The first, the Study of Healthy Aging in African Americans (STAR) included 676 African Americans who completed Multiphasic Health Check-ups (MHC) from 1964 to 1985, during which BMI, blood pressure, blood glucose, and serum total cholesterol were measured. At MHC, participants were either adolescents (n = 333; aged 14 to 25 years) or adults (n = 343; aged 26 to 56 years).

Led by presenting author Kristen George, PhD, MPH, postdoctoral scholar, University of California—Davis, the research showed that hypertension (pooled B = —0.18; 95% CI, –0.33 to –0.03) and diabetes (pooled B = —0.69; 95% CI, –1.15 to –0.24) were associated with worse cognition among both MHC age groups. Additionally, hypercholesteremia was associated with worse cognition in adults at MHC, but not adolescents (adults: B = —0.22 [95% CI, –0.40 to –0.05]; adolescents: B = 0.02 [95% CI, —0.16 to 0.21]; P = .03).

Cognitive domains of verbal episodic memory, semantic memory, and executive function were measured using the Spanish and English Neuropsychological Assessment Scales (SENAS) while linear regression was used to analyze the association between adolescent and adult cardiovascular disease (CVD) risk factors with cognition, adjusted for age, gender, and education. All told, associations were consistent for executive function and verbal memory, but non-significant for semantic memory.

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George and colleagues found that being overweight or obese did not predict late-life cognition regardless of age at MHC but having ≥2 cardiovascular risk factors predicted worse cognition for both MHC age groups (pooled B = —0.24; 95% CI, –0.40 to –0.08). Overall, results from the study suggest that cardiovascular risk as early as adolescence may influence late-life brain health in African Americans.

While STAR did not find any associations between being overweight and late-life cognition, a second study from Adina Zeki Al Hazzouri, PhD, social epidemiologist, assistant professor, Columbia University, and colleagues, became the first to report heightened dementia risk with higher early life BMI—for both women and men.

The studied compiled 5104 older adults from 2 studies, the Cardiovascular Health Study (CHS; n = 2909) and the Health, Aging and Body Composition Study (Health ABC; n = 2195) study. Participants from both studies had a mean age of 72.6 years (standard deviation [SD], 4.2) at enrollment, with 18% of the population being black and 56% female.

Pooled logistic regression models adjusted for midlife and late-life BMI indicated that dementia risk was 1.8 times higher among women who were overweight (odds ratio [OR], 1.8; 95% CI, 1.31—2.54) and 2.5 times higher among those who were obese (OR, 2.45; 95% CI, 1.47–4.06). For men, dementia risk increased with higher early life (obese OR, 2.47; 95% CI, 1.46–4.19) and mid-life BMI (overweight OR, 1.51 [95% CI, 1.11–2.05]; obese OR, 2.00 [95% CI, 1.16–3.42]), in models also adjusted for late-life BMI.

Hazzouri and colleagues noted that dementia risk decreased with higher late-life BMI in both men and women. There was no effect for midlife BMI on dementia risk among women.

To test previous hypotheses about the timing and influence of cardiovascular risk factors such as BMI on AD, researchers gathered data on early and midlife BMI as early as age 18 years from both studies. BMI was summarized by time-weighted averages in early (ages 20 to 49 years), mid (ages 50 to 69 years), and late life (ages 70 to 89 years).

“By identifying, verifying, and acting to counter these Alzheimer’s risk factors that we can change, we can reduce new cases and eventually the total number of people with Alzheimer’s and other dementia,” Maria C. Carrillo, PhD, Alzheimer’s Association chief science officer, said in a statement.³ “Research like this is important in addressing health inequalities and providing resources that could make a positive impact on a person’s life.”

REFERENCES

1. George KM, Peterson R, Gilsanz P, et al. Cardiovascular risk factors in adolescence and adulthood and late-life cognition: study of healthy aging in African Americans (STAR). Presented virtually at AAIC 2020. Poster 47974.

2. Hazzouri AZA, Vittinghoff E, Hoang TD, et al. Association of early life BMI with dementia risk: findings from a pooled cohort analysis. Poster 37958.

3. Alzheimer's Risk Factors May Be Measurable in Adolescents and Young Adults [press release]. Chicago, IL. AAIC. Published July 30, 2020. Accessed July 30, 2020. alz.org/aaic/releases_2020/early-life-risk-factors-dementia.asp.