August 02, 2018
Antihypertensive therapy to lower elevated blood pressure (BP) decreases the risk for dementia and Alzheimer's disease (AD) in older adults, and the benefits may be gained by several different drug classes, new research shows.
Debate continues about whether treating elevated BP or using a specific antihypertensive medication in late life will reduce the risk for dementia, said study investigator Jie Ding, PhD, from the National Institute on Aging, Bethesda, Maryland.
The findings were presented here at the Alzheimer's Association International Conference (AAIC) 2018.
To investigate, the researchers conducted a meta-analysis of individual patient data from six long-term prospective cohort studies: the Age, Gene/Environment Susceptibility-Reykjavik Study; Atherosclerosis Risk in Communities Study; Framingham Heart Study; Honolulu-Asia Aging Study; Rotterdam Study; and 3-C study.
They assessed associations of different classes of BP-lowering drugs to incident dementia and Alzheimer's disease in 31,090 dementia-free community-dwelling participants aged 55 years and older with baseline data on BP and use of BP-lowering drugs who were followed for up to 22 years.
They examined five major drug classes: angiotensin-converting enzyme inhibitors (ACEIs), angiotensin II receptor blockers (ARBs), beta-blockers (BBs), calcium channel blockers, and diuretics.
Within-study Cox proportional hazards analyses were adjusted for propensity scores to control for risk factors. Analyses were stratified by high baseline BP (systolic BP ≥140 mm Hg or diastolic BP ≥90 mm Hg) and normal baseline BP irrespective of medication use, and APOE ε4 carrier status.
During follow-up, 3728 study participants developed dementia and 1741 developed AD.
In adults with high baseline BP, those using any BP-lowering drug, regardless of drug class, had a reduced risk for developing all-cause dementia (hazard ratio [HR], 0.88; 95% confidence interval [CI], 0.79 - 0.98) and Alzheimer's disease (HR, 0.85; 95% CI, 0.74 - 0.99) compared with those not using BP medication, Ding reported.
HRs for incident dementia were similarly reduced among APOE ε4 carriers (HR, 0.77; 95% CI, 0.64 - 0.93), which mainly reflected the associations with ACEIs (HR, 0.75; 95% CI, 0.57 - 0.98), ARBs (HR, 0.65; 95% CI, 0.47 - 0.91), BBs (HR, 0.74; 95% CI, 0.58 - 0.95), and diuretics (HR, 0.75; 95% CI, 0.59 - 0.94).
No significant associations were noted among APOE ε4 noncarriers or in participants with normal baseline BP.
Keith Fargo, PhD, director of scientific programs and outreach for the Alzheimer's Association, told Medscape Medical News that this analysis is "interesting, especially comparing it to the SPRINT MIND study," which was also reported here at AAIC 2018.
As reported by Medscape Medical News, SPRINT MIND showed that aggressive lowering of systolic blood pressure to 120 mm Hg significantly reduces the risk for mild cognitive impairment (MCI).
"What's nice about this meta-analysis," said Fargo, "is the size, 31,000 people, and that it looked at dementia and found a statistical difference for those who were treated vs those who were not in terms of the number of people who developed dementia. So this analysis adds to the overall story especially given that SPRINT MIND is a little bit incomplete at this point," said Fargo.
It's also interesting, he noted, that this meta-analysis looked not only at dementia but also Alzheimer's disease specifically and found a benefit of BP lowering. "This is intriguing," said Fargo, "and suggests that the onset of Alzheimer's disease may be slowed through treatment of high blood pressure, which I think is good news."
The study had no commercial funding. The authors have disclosed no relevant financial relationships.