Men’s social isolation
linked to higher heart disease risk
November 11, 2003
ORLANDO, FL (AHA)
Older men who have few personal relationships may have increased
risk of heart disease, according to a report presented at the
American Heart Association’s Scientific Sessions 2003.
In a study examining factors that influence successful aging,
researchers found that among a group of men in their 70s, social
isolation was linked to increased levels of C-reactive protein
(CRP), interleukin-6 (IL-6) and fibrinogen in the blood. These
blood components are elevated during inflammation.
Recent research has suggested that inflammation in the body
is a risk marker for cardiovascular disease. People with
elevated CRP and fibrinogen have higher risks for heart disease
“Social isolation may influence these different inflammatory
markers and may be one way social relationships influence our
health,” said lead author Eric B. Loucks, Ph.D., research fellow
at Harvard School of Public Health in Boston. He is a
co-investigator for this endeavor in the ongoing MacArthur
Successful Aging Study, a research project that follows 1,189
men and women from Durham, N.C., Boston, and New Haven, Conn.
Social relationships have been linked to better health and
protection against heart disease in many studies. However, the
unanswered question is how social relationships translate into
biological processes that affect a person’s health.
Loucks and his colleagues at Harvard and the University of
California, Los Angeles, investigated CRP, IL-6 and fibrinogen
as potential biological links between friends, family and
As part of that study, researchers drew and froze blood
samples in 1988. They gave a questionnaire to participants to
gauge their social relationships. The questions included
marital status, the number of close friends and family members,
and the extent of religious and social club participation.
In 1988, the potential importance of inflammatory markers in
heart disease had not been fully recognized, nor did today’s
highly sensitive techniques exist to measure CRP and IL-6.
Several years ago, however, the research team began analyzing
blood samples drawn from 388 men and 438 women when they entered
the MacArthur study. Levels of the participants’ biomarkers
were correlated with their degree of social relationships.
Researchers failed to find any correlation between the degree
of social isolation in women and their levels of the
“Men may respond differently than women to social
relationships,” Loucks said.
“Women also live longer than men,” he added. “So another
possibility is that in this particular age group, 70 to 79,
men’s inflammatory biomarkers may be more influenced by social
relationships than women’s at that age.”
Among the 388 men, CRP levels were 3.69 for those in the
lowest fourth of social network index (i.e., those most socially
isolated) compared to 2.33 for those in the highest fourth.
Levels of IL-6 were 5.54 for those in the lowest fourth and 4.10
in the highest fourth. Fibrinogen levels were only slightly
different: 2.98 compared to 2.73.
When the researchers statistically controlled for age,
education, race, physical functioning, and the presence of other
diseases, they still found a significant inverse correlation
between people’s social network and their levels of the three
However, when the team further controlled for behavioral
factors that can affect health – such as smoking, alcohol
consumption, physical exercise and obesity – the association was
no longer statistically significant.
This last finding shines further light on how social
relationships may influence a person’s level of biomarkers
because social relations may influence behavior, Loucks noted.
“If your spouse eats a high-fat diet, chances are you will
eat a high-fat diet, or if your spouse exercises, chances are
you will too,” he said. “People who have a low variety of
social relationships may not have people to support them in
behaviors such as exercise, or in stopping smoking.
“Stress can raise levels of IL-6 and fibrinogen and may be
another pathway by which social isolation can influence health,”
Future long-term studies are planned to examine causes.
Co-authors are Lisa F. Berkman, Ph.D.; Tara L. Gruenewald,
Ph.D. and Teresa E. Seeman, Ph.D.