NEW YORK, Dec 02 (Reuters Health) -- The dangers of high blood pressure -- heart attack, stroke, kidney disorders -- are often in the news. But in a report released Thursday, Japanese researchers conclude that in men over the age of 65, low blood pressure is just as big a health risk, increasing the chances of dying from cancer or lung disease.

The study findings suggest that among men over 65, low blood pressure may quadruple the risk of dying from non-cardiac illnesses such as respiratory disease and cancer, while high blood pressure is linked to a four times higher risk of dying from cardiovascular disease and stroke.

Researchers from Kochi Medical School in Japan, led by Dr. Kiyohito Okumiya, studied the relationship between blood pressure and mortality in the older residents of a rural Japanese town. They asked 1,186 men and women aged 65 and older take their blood pressure at home four times a day for 5 consecutive days.

Over a 4-year follow-up period, 134 participants died. After adjusting the analysis for factors such as age, health history, smoking and activity level, the investigators found that among men, those with systolic blood pressure (the first number) between 125 and 134 mm Hg had the lowest risk of dying during the follow-up period.

The two groups most likely to die were the extremes: men with systolic blood pressure of 145 mm Hg and higher, and men with systolic pressure below 125. Both groups were four times more likely to die than the low-risk group.

Although men with very high and very low systolic blood pressure were equally likely to die over the 4-year period, what caused their deaths was very different. The relationship between systolic blood pressure and death from cardiovascular disease was straightforward -- the higher the systolic pressure, the greater the risk of dying.

Men with low systolic pressure, however, were at increased risk for death caused by non-cardiovascular conditions. Writing in the December issue of the Journal of the American Geriatrics Society, Okumiya and his colleagues suggest that in older men, low systolic blood pressure may serve as an early sign of a non-cardiovascular condition.

Previous studies suggested that frailty might be the link between low blood pressure and increased mortality risk in elderly men. But the new study contradicts this -- "There was no significant evidence that frailty is more prevalent in the lowest or highest systolic (blood pressure) group than in intermediate groups," the team writes.

In an editorial in the same issue, Dr. Grant W. Somes of the University of Tennessee in Memphis and colleagues call the study findings "a new and potentially important contribution" to our understanding of blood pressure in the elderly. They note that in a young and healthy population, "lower blood pressure is better," but that among older patients the ideal blood pressure has yet to be determined.

Agreeing that low blood pressure among the elderly may indicate an underlying disease, Somes and his colleagues suggest that "perhaps those with low blood pressure deserve more careful monitoring."

SOURCE: Journal of the American Geriatrics Society 1999;47:1415-1421, 1477-1478.