COPENHAGEN—Among people age 90 and older without dementia, developing hypertension at older ages may lower the risk of dementia, according to research presented at the 2014 Alzheimer’s Association International Conference.
The risk of dementia appears to decrease with increasing age of hypertension onset. In addition, dementia risk may decrease as blood pressure increases, and the use of antihypertensive medications does not account for this association, said Maria Corrada-Bravo, ScD, Associate Adjunct Professor of Neurology and Epidemiology at the University of California, Irvine.
Maria Corrada-Bravo, ScD
Results are from the 90+ Study, an ongoing, population-based investigation of aging and dementia. Participants were 90 or older in 2003, did not have dementia, and had taken part in the Leisure World Cohort Study, which was initiated in the early 1980s. In the Leisure World study, participants who lived in a retirement community received a mailed questionnaire about their health and lifestyle factors. The two studies collected information about whether participants ever had been diagnosed with hypertension and, if they had been, what their age was at diagnosis. People who joined the 90+ Study were followed up every six months with a multidisciplinary assessment that included screening for dementia.
More than two-thirds of participants in the 90+ Study were women, which is consistent with the gender distribution of people age 90 or older, said Dr. Corrada-Bravo. Participants’ mean age was 69 when they joined the Leisure World Cohort Study and 93 when they joined the 90+ Study. Approximately 43% of participants had at least a college degree. The average length of follow-up was about three years, and approximately 41% of participants developed dementia during follow-up.
The risk of dementia was similar for participants with hypertension onset before age 80 and those without a history of hypertension. Risk of dementia was 41% lower, however, for people who developed hypertension in their 80s, compared with people without a history of hypertension. Participants who developed hypertension in their 90s had a 55% decreased risk of dementia, compared with participants without a history of hypertension.
Compared with participants with normal blood pressure, risk of dementia decreased with increasing blood pressure. Participants with the highest levels of blood pressure (ie, stage 2 hypertension) had the lowest risk of dementia. The researchers’ analysis adjusted for the use of antihypertensive medications, and the association between blood pressure and dementia risk did not result from medication, said Dr. Corrada-Bravo.
“For people at very old ages, developing hypertension may be beneficial for maintaining intact cognition,” she added. “Hypertension or a certain level of blood pressure may be needed to maintain adequate blood flow and oxygenation in the brain, but we need to do more research to understand better what the risk–benefit ratio of treating new-onset hypertension at this age is in relation to dementia and other outcomes.”
—Erik Greb