Midlife blood pressure linked to dementia risk

NEW YORK (Reuters Health) - Pulse pressure in middle age is not independently associated with the development of dementia later in life, according to findings from the Honolulu-Asia Aging Study.

As earlier studies have found, the blood pressure component that most strongly predicts dementia is midlife systolic blood pressure, the top number of a blood pressure reading.

Dr. Lenore J. Launer, from the National Institute on Aging in Bethesda, Maryland, and colleagues examined whether the pulsatile (pulse pressure) or the nonpulsatile component of blood pressure contribute to this association.

Midlife blood pressure was measured in Japanese American men between 1971 and 1974 and signs of dementia were assessed in later in life. A total of 2505 men who were dementia free in 1991 were re-examined for dementia on two occasions between 1994 and 1999. The patients' ages ranged from 71 to 93 years.

A total of 189 cases of Alzheimer's disease or vascular dementia were diagnosed over an average of 5.1 years of follow-up. Dementia was not associated with either high or low pulse pressures, the investigators report in the January issue of the medical journal Stroke.

On the other hand, "the risk increased as blood pressure increased," Launer told Reuters Health. "Someone with a systolic blood pressure of over 140 mm Hg, has a higher risk for dementia than someone with systolic blood pressure between 120 and 139 mm Hg, who has a higher risk than someone with systolic blood pressure less than 120 mm Hg," she noted.

"This risk for dementia was highest in persons with high blood pressure who had never been treated for this condition," Launer added.

The findings suggest that "processes leading to dementia begin many years before someone is diagnosed with dementia," she pointed out. "Prevention and treatment of high blood pressure in middle age may prevent dementia in (old) age."

SOURCE: Stroke, January 2006.