Constipation might signal Parkinson's.

Constipation is a common problem in people who have Parkinson's disease. A new study now suggests that men who have constipation in late middle age are more likely to develop Parkinson's than are those who have more frequent bowel movements.

Between 1971 and 1974, researchers enrolled 8,006 Hawaiian men of Japanese ancestry between ages 45 and 68 in a health study. The scientists recorded the men's health data and then documented their health status again in the 1990s. In the interim, 96 men developed Parkinson's disease.

The researchers found that men who had fewer than one bowel movement per day in the 1970s were nearly three times as likely to develop Parkinson's disease as were men who had averaged one per day, and four times as likely as were men who averaged more than one. These figures accounted for differences due to smoking and other factors, the researchers report in the Aug. 14 NEUROLOGY.

The data don't suggest that constipation causes Parkinson's disease. But the study might permit scientists to identify people at risk of developing Parkinson's, says study coauthor Robert D. Abbott, a biostatistician at the University of Virginia School of Medicine in Charlottesville and the Pacific Health Research Institute in Honolulu. That, in turn, could help researchers designate candidates for experimental treatments designed to protect against the disease, he says.