Women who are socially isolated have an increased risk for high blood pressure, researchers report. But men, not so much.

Scientists used data on 28,238 Canadian men and women aged 45 to 85 who are participating in a large continuing study on aging.

The researchers found that compared with married women, single women had a 28 percent higher risk of hypertension, divorced women a 21 percent higher risk, and widowed women a 33 percent higher risk.

Social connections were also significant. Compared with the one-quarter of women with the largest social networks — which ranged from 220 to 573 people — those in the lowest one-quarter, with fewer than 85 connections, were 15 percent more likely to have high blood pressure.

The associations were different, and generally weaker, in men. Men who lived alone had a lower risk of hypertension than men with partners, but the size of men’s social networks, or their participation in social activity, was not significantly associated with high blood pressure.

The study, in the Journal of Hypertension, controlled for many factors that affect blood pressure, including age, education, smoking, alcohol use and depression.

The senior author, Annalijn I. Conklin, an assistant professor at the University of British Columbia, said that the most important finding is that social ties seem to be more meaningful for women than for men. “Social ties matter for cardiovascular health,” she said, “and they matter more for women.”