Uncontrolled high blood pressure means more cognitive problems in old age

Study underscores another keyreason to control hypertension

People with high blood pressure and their doctors have a new reason to work at controlling this common but high-risk condition: As patients get older, they might otherwise have worse-than-normal problems with short-term memory and verbal ability. New research shows that uncontrolled hypertension puts people at higher risk for sharper drops in these cognitive functions than does blood pressure that’s normal due to diet, exercise and/or medication. The study appears in the current issue of Neuropsychology, which is published by the American Psychological Association (APA).

Because blood pressure typically increases with age, hypertension affects 60 percent of adults age 60 and older. However, this “silent killer” often goes undetected or inadequately treated, leaving nearly 40 percent of older hypertensive people with continued high readings — even with treatment. As a result, the findings suggest that a substantial number of older people with uncontrolled hypertension will experience significant cognitive declines, especially because with age, hypertension becomes more common and harder to control.

Researchers at the Veterans Affairs (VA) Boston Healthcare System, Harvard Medical School and the Boston University School of Public Health looked at a subset of men in the VA Normative Aging Study, a longitudinal study that started in 1963 and added neuropsychological tests in 1993. In this smaller cross-sectional study, 357 men from the larger sample averaged 67 years of age, lived in the community, didn’t have dementia or other serious medical problems, and showed stable blood pressure over a three-year interval. Hypertension was defined as measuring 140/90 and higher.

Co-authors Christopher Brady, PhD, Avron Spiro III, PhD, and J. Michael Gaziano, MD, MPH, found that the older the men, the predictably lower their overall neuropsychological performance. However, older men in the sample with uncontrolled hypertension did significantly worse on specific tests of verbal fluency (generating words in a given category) and immediate recall of a word list (short-term memory).

The uncontrolled hypertensives’ decrements on fluency were 2.4 times as great as for those with normal pressure; their decrement with immediate recall was 1.3 times as great. That means by the age of 80, men with uncontrolled hypertension could generate seven fewer words in a given category, and recall about one and a half fewer words on average, than the other 80-year-old men in the study.

“The findings suggest that uncontrolled hypertension produces specific cognitive deficits beyond those attributable to age alone,” the researchers report. They also note that their findings are consistent with other studies that suggest that anti-hypertensive drugs do not hurt cognition, given that the men with controlled hypertension who used them in this study did as well as men who had naturally normal blood pressure. The researchers speculate that high blood pressure somehow exacerbates the normal effects of age on the frontal lobes, making it even harder to quickly retrieve information such as words.

The authors raise the possibility that the actual proportion of cognitive problems among older people with uncontrolled hypertension in the general population may actually be larger than seen in the study, because this sample used healthy men with no other health problems. Uncontrolled hypertension also is known to raise the risk of vascular dementia, the second most common form of serious cognitive impairment after Alzheimer’s disease.