For the Oldest Old, Lower Blood Pressure May Not Always Be Better

While most studies examining the relationship between blood pressure and cognitive function find that high blood pressure in middle age is associated with cognitive impairment in later life, findings regarding the relationship between blood pressure in late life and even later cognitive function have been conflicting. Some suggest a link between high blood pressure in late life and subsequent cognitive decline; others do not.

“The Effect of Age on the Association Between Blood Pressure and Cognitive Function Later in Life,” an important study in last month’s Journal of the American Geriatrics Society, sheds new light on the issue.¹ With the mean age of long-term care residents exceeding 80, the study’s findings are particularly relevant to this patient population. In the study, Monique MB Breteler, MD, PhD, of Rotterdam’s Erasmus MC University Medical Center and colleagues¹ analyzed data from both the Rotterdam Study and the Leiden 85-plus Study, two prospective, population-based cohort studies.

The Breteler team’s analysis included nearly 3100 men and women, initial ages 55 to 84, from the Rotterdam Study, and nearly 300 men and women, all with an initial age of 85, from the Leiden Study. The systolic and diastolic blood pressure of all participants was measured at baseline, and cognitive function was assessed in Rotterdam participants in 10-year age groups, and in Leiden study participants at age 85. In participants age 65-74, higher baseline blood pressure was related to poorer cognitive function 11 years later, Breteler and colleagues found. But in participants age 75 and older—particularly those age 85 and older—higher blood pressure appeared to be related to better cognitive function at the end of follow-up.

The researchers speculate that, in the “oldest old,” the effect of higher blood pressure on cerebral perfusion may help preserve cognitive function. “With increasing age, basal cerebral blood flow decreases, possibly caused by impaired cerebral autoregulation through atherosclerosis or endothelial dysfunction,” they write. “In the oldest old, a higher blood pressure may therefore be required to prevent cerebral hypoperfusion and preserve cognitive function.” The “current directive that “lower is better” may not apply to blood pressure levels in the very old,” Breteler and colleagues warn. In closing, they argue that further research clarifying the risks and benefits of blood pressure lowering in the oldest old is needed. We concur.