One-Third of Dementia Cases Laid to Small Blood Vessel Damage

Findings back control of hypertension, diabetes that may contribute to cumulative effects

SUNDAY, April 6 (HealthDay News) -- Small blood vessel damage caused by hypertension and diabetes may be among the leading causes of dementia, according to new research.

The findings provide an additional reason to control these common conditions, according to Dr. Thomas Montine of the University of Washington, who was to present the study Sunday at Experimental Biology 2008 in San Diego.

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The autopsied brains of a third of men and women with dementia or cognitive decline showed evidence of small vessel damage -- a cumulative injury that can result from multiple small strokes caused by hypertension and diabetes. The strokes are often so small that the person notices nothing until the cumulative effect reaches critical mass, the researchers said.

Meanwhile, 45 percent of the risk for dementia was associated with pathologic changes of Alzheimer's disease. Another 10 percent risk was linked to Lewy bodies, which are neocortical structural changes that indicate a degenerative brain disease known as Lewy Body Dementia, a possible variant of Alzheimer's and/or Parkinson's disease, the study found.

The finding about small vessel disease challenges conventional wisdom and conclusions from most autopsy studies of brain aging and dementia, Montine said in a prepared statement.

The broader population sample on which the autopsy study was based may be reason for the differing results, he said. Most previous research had focused on participants in Alzheimer's disease center studies, or was limited to one gender, ethnic or professional group. The individuals in the new study were part of a large managed care program and representative of the Seattle urban and suburban area they came from: white, Asian, African-American and Hispanic, with a range of educational and professional levels.

In the study, which ran from 1994 to 2006, some participants suffered cognitive impairment and dementia, while others did not. Roughly a third of all 3,400 participants died, and autopsies were performed on the 221 who had given permission for this to be done.

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The American Heart Association has more about controlling high blood pressure.

-- Kevin McKeever