Link between dementia and hypertension

Hypertension appeared to predict the progression of dementia among older adults with certain cognitive deficits, including the ability to organize thoughts and make decisions, but not others, such as those with memory dysfunction.

“We know from a large number of papers now that the hallmark of Alzheimer’s disease is memory impairment, whereas vascular cognitive impairment due to multiple strokes are typically associated with hypertension,” said a study researcher Vladimir Hachinski, MD, of the department of clinical neurological sciences at the University of Western Ontario in London, Canada. However, up until now, the literature has been confusing about the role of late-life hypertension in progression to dementia, with some studies’ results supporting the link and others not supporting it.

“Because hypertension is a major risk factor for vascular brain diseases and vascular cognitive impairment, we postulated that the cognitive domain of dysfunction may be the crucial factor that determines the association between hypertension and cognitive deterioration,” Hachinski and colleagues wrote.

They analyzed data from 990 adults (mean age, 83.06 years) who had experienced cognitive impairment but not dementia, and who had participated in the Canadian Study of Health and Aging in 1991; 1995 to 1996; and 2001 to 2002.

During the five-year follow-up, the researcher found that dementia developed at about the same rate among participants with and without hypertension (59.5% vs. 64.2%; P=.32). However, results were different when they compared the progression to dementia among patients with hypertension and three patterns of cognitive impairment — those with executive dysfunction alone, those with memory dysfunction alone and patients with both types of cognitive dysfunction. Patients with executive dysfunction alone who had hypertension were more likely than patients without hypertension to progress to dementia (57.7% vs. 28.0%; P=.02).

“The implication is that if we treat high BP we could decrease progression [to Alzheimer’s disease] or slow it,” Hachinski said. “We potentially could be delaying or preventing cognitive impairment, and that’s huge. The big gain is not in mortality but to push morbidity to the end of life.”

As medical advances continue to extend the average human lifespan, Hachinski advocates for broader preventive strategies to improve the quality of life for aging populations. He called for more prospective studies to explore the means by which hypertension can be most effectively lowered, including research into behavioral as well as pharmaceutical strategies.

Currently, Hachinski and colleague Richard K. Chan, MD, also of the University of Western Ontario, are conducting an ongoing trial to determine whether reinforcement from family and peers helps patients at risk for stroke make necessary lifestyle changes, including losing weight and lowering BP.