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Lower blood pressure may not reduce risk for Alzheimer's disease

Mendelian randomization analyses found an association between lifetime exposure to higher systolic blood pressure and decreased risk for Alzheimer’s disease.

“Alzheimer’s disease prevalence is rising, further increasing the social and economic burden of this disease. Epidemiological studies have aimed to identify potentially modifiable risk factors that could be targeted in preventive measures to reduce incidence of [Alzheimer’s disease]. These include type 2 diabetes and glycemic traits, hypertension, obesity, dyslipidemia, smoking, physical inactivity, depression, and low educational attainment,” study researcher Søren Østergaard, MD, PhD, of the Aarhus University Hospital in Risskov, Denmark, and colleagues wrote in PLoS Medicine. “However, this suggestion is predicated on these risk factors having causal effects on [Alzheimer’s disease] risk, which is currently uncertain.”

Søren Østergaard

To assess associations between potentially modifiable risk factors and Alzheimer’s disease, researchers conducted Mendelian randomization analyses among a cohort of 17,008 patients with Alzheimer’s disease and 37,154 cognitively healthy elderly controls. Researchers examined type 2 diabetes, fasting glucose, insulin resistance, body mass index, total cholesterol, HDL cholesterol, LDL cholesterol, triglycerides, systolic blood pressure, smoking initiation, smoking quantity, university completion and years of education.

Genetically predicted higher systolic blood pressure (OR = 0.75; 95% CI, 0.62-0.91) and genetically predicted smoking quantity (OR = 0.67; 95% CI, 0.51-0.89) were associated with lower risk for Alzheimer’s disease. Genetically predicted smoking initiation was not associated with risk for Alzheimer’s disease. The researchers noted they were unable to stratify by smoking history.

There were no causal associations between Alzheimer’s disease risk and glycemic traits, type 2 diabetes, BMI or educational attainment (P > .01 for all).

“We found associations between genetically predicted higher [systolic blood pressure] and lower [Alzheimer’s disease] risk. This finding is contrary to the notion that societal interventions to lower blood pressure will reduce the incidence of [Alzheimer’s disease]. However, since there is a strong association between higher [systolic blood pressure] gene scores and exposure to antihypertensive treatments, there is a need to evaluate the possible protective role of some of these substances against [Alzheimer’s disease], independent of their effects on blood pressure.” – by Amanda Oldt

Disclosure: Østergaard has received speaking fees, consultant honoraria and travel support from Janssen-Cilag and travel support from Bristol-Myers Squibb. Please see the full study for a list of all other authors’ relevant financial disclosures.