Science

High blood pressure may predict dementia risk

Seniors with high blood pressure may face a higher likelihood of developing a type of dementia, a new Canadian study suggests.

Seniors with high blood pressure may face a higher likelihood of developing a type of dementia, a new Canadian study suggests.

About one in five Canadians has high blood pressure. For years, doctors have known that hypertension is a risk factor for stroke. The new research suggests high blood pressure may also be a signal for behavioural changes and mental decline later in life. 

'This study may have profound implications for community dwellers with cognitive impairment, no dementia.'— Study's authors

The study, published in the February issue of Archives of Neurology, was based on data from the Canadian Study on Health and Aging.

Dr. Shahram Oveisgharan of the University of Western Ontario in London and colleagues studied 990 adults with an average age of 83 with cognitive impairment showing age-related brains changes, but no full dementia.

They found mental decline came in two forms. People would become increasingly impaired in how they organize thoughts and make decisions, known as executive dysfunction, or they would start to lose their memory.

Among those with executive dysfunction only, the presence of hypertension was associated with an increased risk of developing dementia — 57.7 per cent of those with high blood pressure progressed to dementia, versus 28 per cent of those without.

Overall during the five-year followup period, dementia developed at about the same rate among participants with and without hypertension (59.5 per cent of those with high blood pressure versus 64.2 per cent of those without).

As well, no link was found for the memory loss type of mental decline.

Prevention strategy

"This study may have profound implications for community dwellers with cognitive impairment, no dementia," the study's authors concluded.

"We show herein that the presence of hypertension predicts progression to dementia in a subgroup of about one-third of subjects with cognitive impairment, no dementia."

There is no preventive or therapeutic way to mitigate the public burden of dementia, the researchers noted.

But treating those diagnosed with mild cognitive impairment with anti-hypertensive drugs could help reduce the rate of progression to dementia in the long term, the researchers proposed.

The team acknowledged limitations of the study. For example, about 10 per cent of the subjects refused detailed clinical exams. About 30 per cent of the subjects died over the course of the study, and their cognitive status was estimated from death certificates and interviews with their spouses or close relatives.

The research was supported by the Alzheimer's Association.

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