Social isolation may be associated with poor health consequences, including heart disease, researchers say.

People with atherosclerosis, or hardening of the arteries, and who live alone may be at higher risk of dying than those living with others, an international study finds.

Heart attack risk may be associated with how connected people are with others. (Fabrizio Bensch/Reuters)

Learning more about how living alone affects health is important, considering that about one in seven American adults live alone. People in both developed and developing countries increasingly live apart from friends and family and communicate and work remotely.

In Monday’s online issue of the Archives of Internal Medicine, Dr. Jacob Udell of Brigham and Women's Hospital and Harvard Medical School in Boston and his co-authors said living alone was associated with four-year mortality (14.1 per cent vs. 11.1 per cent) and cardiovascular death (8.6 per cent vs. 6.8 per cent) compared with those not living alone.

Living alone was riskier among those aged 45 to 65, but not those 66 or older, the researchers found.

"Living alone may be a marker of a stressful situation, such as social isolation due to work or personal reasons, which can influence biological effects on the cardiovascular system," Udell said.

"Also, patients who live alone may delay seeking medical attention for concerning symptoms, which can increase their risk of dying from a heart attack or stroke," he added in a release.

The study looked at 44,573 people in North America, Europe, Japan, Middle East, Latin America and Asia. Of these, 19 per cent were living alone.

Participants either had atherothrombosis such as heart disease, angina and stroke, or had at least three risk factors for cardiovascular disease.

Social factors can undermine health

The researchers said the findings should encourage doctors to ask patients with cardiovascular disease if they live alone.

In a second study appearing in the same issue, Dr. Carla Perissinotto, of the University of California, San Francisco, found that loneliness was associated with an increased risk of death during the study's six-year followup period.

Older people who said they felt lonely tended to have more difficulty taking care of themselves, which could increase the risk of dying from any cause, after considering depression.

"Loneliness is a negative feeling that would be worth addressing even if the condition had no health implications," Emily Bucholz of Yale University in New Haven, Conn., concluded in a journal commentary accompanying the research papers.

"Nevertheless, with regard to health implications, scientists examining social support should build on studies such as those published in this issue and be challenged to investigate mechanisms as well as practical interventions that can be used to address the social factors that undermine health."

Udell's research was supported by Sanofi Aventis, Bristol-Myers Squibb, Waksman Foundation in Tokyo, Canadian Institutes for Health Research and the Canadian Foundation for Women's Health. Perissinotto's study was funded by the U.S. National Institute on Aging.