Consistently High BP Seems to Up Dementia, AD Risk

BOSTON -- Older individuals who failed to achieve blood pressure control seemed to be at an increased risk of developing dementia and/or Alzheimer's disease, researchers said here.

The mid-to-late life trajectory risk of developing dementia was nearly twice as great among individuals who had persistently elevated blood pressure (BP) after age 55 and those people whose blood pressure was less than 140 mm Hg systolic and 90 mm Hg diastolic (hazard ratio 1.96, 95% CI 1.25-3.06), reported Emer McGrath, MBChB, PhD, of Brigham & Women's Hospital/Massachusetts General Hospital and Harvard Medical School in Boston, and colleagues.

"We did see evidence that elevated pressure in mid-life is associated with increased risk of dementia in older life," McGrath said in a presentation at the American Academy of Neurology (AAN) annual meeting. "I think that in middle-aged adults and older adults with elevated blood pressure, it would seem that treating blood pressure would diminish the risk of dementia."

"Hypertension is the most important modifiable risk factor for cerebrovascular pathology contributing to stroke and dementia," she said. "Mid-life -- ages 40 to 64 years -- and late-life (65 years and older) elevated blood pressure have been associated with an increased risk of cognitive decline."

McGrath's group accessed data from the Framingham Heart Study, specifically the Framingham Offspring Study from which they identified 1,440 individuals (758 women) for whom complete BP data were available. All the participants in the study were at least age 60, and had undergone a BP examination when they were age 55 years. At the time of their seventh exam, participants had a mean age of 69, and they did not have a dementia diagnosis. Exam seven was performed between 1998 and 2001. About 50% of the current study population with elevated BPs were taking antihypertensive medication.

"We assessed the impact of mid-life hypertension (≥140/90 mmHg), late-life hypertension, lower late-life blood pressure (<100/70 mmHg), persistent hypertension from mid-to-late life, and steeper than average decline in blood pressure from mid-to-late life on the risk of incident dementia due to all-causes," the authors explained.

After a mean follow-up of 10 years, 107 people in the study were diagnosed with dementia, with 81 receiving a diagnosis of Alzheimer's disease.

The researchers also reported that among people with low to normal midlife BPs (≤140/90 mmHg), a steeper than average decline in systolic BP from mid-to-late life was linked to a more than a twofold increased risk of dementia (HR 2.40, 95% CI 1.39-4.15).

"There had been some studies in the literature that lowering blood pressure below 140/90 in this population could have increased the risk of dementia," McGrath said. "What we saw in this study is that lowering blood pressure in patients who were at 140/90 appears to increase the risk of cognitive decline, so for these individuals lowering blood pressure may be harmful. I would say we need to replicate these findings in other studies."

But persistently high BP in older individuals requires treatment. "Our data highlight the potential sustained cognitive benefits of lower mid-life blood pressures," she said.

AAN session moderator David Wolk, MD, of the University of Pennsylvania in Philadelphia, told MedPage Today, "I think that in some internal medicine practices, clinicians tend to get a little looser in controlling blood pressure later in life, with the idea that elevated blood pressure is an accumulated risk and in later life it may not matter as much. I think there often is more concern about hypotension and its consequences as well."

He added that preventive medicine concerns tend to drop off as patients get older, accumulating evidence shows that clinicians need to continue with preventive medicine.

Wolk noted that in the study by McGrath's group "it looks like maintained high blood pressure of cases in which normal blood pressure declines accounts for most of the dementia cases. The bottom line here is that keeping your body healthy -- including blood pressure -- also tends to keep your brain healthy," he said.