Late-Life Hypertension May Help Protect Against Alzheimer’s
New study results published online in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association suggest that the onset of high blood pressure later in life is associated with lower dementia risk after age 90, especially if hypertension is developed at age 80 or older.
High blood pressure and other heart-health risk factors are generally thought to increase dementia risk. These new findings challenge this idea and add to scientists’ understanding of hypertension and dementia risk over the course of a person’s life.
Researchers at the University of California, Irvine followed 559 people for an average of 2.8 years to investigate the relationship between dementia, age of hypertension onset and blood pressure measurements. All participants are from an ongoing, longterm study of people age 90 and older known as The 90+ Study. At enrollment, participants did not have dementia, were 93 years old on average, and 69 percent female. They received dementia assessments every six months during the study period. During the follow-up period, 224 (40 percent) of the participants were diagnosed with dementia. The researchers found that study participants who reported hypertension onset at age 80 to 89 were 42 percent less likely to develop dementia after age 90 compared with those who reported no history of high blood pressure.
Participants whose hypertension began at age 90 or older were at even lower risk—63 percent less likely to develop dementia. These associations were statistically significant and independent of whether participants were taking medications to treat hypertension.
“In this first-of-its-kind study, we find that hypertension is not a risk factor for dementia in people age 90 or over, but is actually associated with reduced dementia risk,” says first author Maria Corrada, M.S., Sc.D., Professor of Neurology and Epidemiology at the University of California, Irvine. “This relationship had not yet been examined in groups of older people in their 80s or 90s, known as the ‘oldest old.’” (Note: Most data from younger patients show that high blood pressure is a risk factor for Alzheimer’s disease and dementia. It is recommended that blood pressure be controlled to lessen risk in this age group.)
The authors also measured study participants’ blood pressure at enrollment. Those in the hypertensive range at baseline were at lower risk for dementia compared to those with blood pressure in the normal range. While these results were not statistically significant, the researchers observed that dementia risk declined as hypertension severity increased—a trend consistent with the idea that, in this age group, hypertension may protect the brain from insults that lead to dementia.