Social Isolation May Lead to Poor Health Behaviors

Charlene Laino

November 13, 2003

Nov. 13, 2003 (Orlando) — Researchers seeking to find out why social isolation can adversely affect cardiovascular outcomes have found that changes in health behavior may be to blame.

The study, presented here this week at the American Heart Association (AHA) Scientific Sessions, also showed that the inflammatory markers C-reactive protein (CRP), interleukin-6 (IL-6) and fibrinogen may be biomarkers for social isolation in men.

Compared with men in the lowest quartile for social networking, men in the highest quartile had significantly higher levels of all three inflammatory markers, reported Eric B. Loucks, PhD, a research fellow at Harvard School of Public Health in Boston, Massachusetts.

For the study, 388 men and 438 women enrolled in the MacArthur Successful Aging Study, a longitudinal study of people aged 70 to 79 years, were administered a six-question survey designed to assess social isolation.

"We asked how close they were to their friends and family, whether they belong to any clubs or social groups, if they were married and if they attend religious services," Dr. Loucks said. Each answer was assigned a 0 or 1 value, with the values added up to arrive at a social network score for each participant.

CRP levels were 3.69 mg/L for men in the lowest quartile of the social network index compared with 2.33 mg/L for those in the highest quartile ( P = .03). Levels of IL-6 were 5.54 pg/mL for men in the lowest quartile and 4.10 pg/mL for those in the highest quartile ( P = .01). Fibrinogen levels were 2.98 mg/mL and 2.73 mg/mL, respectively ( P = .02).

The researchers failed to find any correlation between the degree of social isolation in women and their levels of the inflammatory biomarkers.

A multivariate analysis that controlled for age, education, race, physical functioning, and comorbidities also found a significant inverse correlation between social networking and levels of the three biomarkers. However, when the analysis further controlled for behavioral factors such as smoking, alcohol consumption, physical exercise, and obesity, the association was no longer statistically significant, Dr. Loucks reported.

"This is the most interesting finding," he told Medscape. "It means that social isolation may be influencing health through these health behaviors," he said, adding that long-term studies are planned to examine the issue.

Valentin Fuster, MD, professor of medicine and cardiology at the Zena and Michael A. Wiener Cardiovascular Institute at Mount Sinai School of Medicine in New York City and a past president of the AHA, agreed. "This is the critical issue," he told Medscape. "Isolation leads to poor health behaviors. Regardless of CRP levels, a person who is alone is more likely to eat poorly, smoke, and drink. The increase in CRP may be manifesting through these behaviors."

Dr. Fuster advised against concluding that there is a sex effect, however. "Probably the study did not have the power, the numbers, to show an association in women, " he said. "We have to be careful in making gender statements here, although it is possible that women may be less likely to be isolated." From a practical viewpoint, the study raises the possibility that CRP levels can be used as a biomarker for poor health behaviors that the patient may try to hide from the physician, Dr. Fuster said.

If older patients are socially isolated, Dr. Fuster advises them to get a pet. "Studies have shown that even having a dog or cat can help to improve health outcomes."

AHA Scientific Sessions 2003: Abstract 3378. Presented Nov. 11, 2003.

Reviewed by Gary D. Vogin, MD

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