May 24, 2002 Lonely people have a greater risk of heart disease, possibly due to differences in how their cardiovascular system reacts in times of stress rather than because of unhealthy behaviors, according to a new study published in the May/June issue of Psychosomatic Medicine. The study shows that when performing mentally and emotionally stressful tasks, lonely college students had increased blood pressure due to increased resistance to blood flow that may be harmful in the long run. In contrast, non-lonely students had increased blood pressure from increased cardiac output, a more normal response to stress.
The lonely students had resistance to blood flow before the stressors too, suggesting that these cardiovascular differences were pervasive.
In a parallel study of older subjects, systolic blood pressure rose with age in lonely men and women while it remained more stable in men and women who were not lonely.
“Differences in the [mechanisms of blood flow] observed throughout the session in younger adults may contribute to elevated blood pressure across time in lonely adults,” says John T. Cacioppo, Ph.D., of the University of Chicago.
Both chronically high blood pressure and vascular resistance have been linked to increased risks of heart disease.
The study also showed that lonely people were no different from the non-lonely in terms of behavioral risk factors such as drinking, smoking, diet and compliance with medical treatments. The authors suggest that this may mean researchers need to look elsewhere to understand the apparent increased risk of disease in the lonely.
For instance, Cacioppo and colleagues found that although lonely individuals slept as many hours as non-lonely individuals, sleep for the lonely was less restorative. They suggest that restorative behaviors in generally may be less effective in lonely than non-lonely individuals.
The first study included 45 male and 44 female undergraduate students from Ohio State University. They were given a questionnaire on loneliness and monitored during one task involving mental arithmetic and one task involving writing and giving a speech to defend themselves against a false accusation of stealing.
Blood pressure before and during these stress-inducing tasks rose similarly for both the lonely and non-lonely students. However, lonely students had significantly higher vascular resistance and lower cardiac output than non-lonely students did.
“Previous research has shown that passive coping is associated with elevated [blood pressure] due to vascular resistance, whereas active coping is associated with elevated [blood pressure] due to increases in [cardiac output],” the authors say. “The parallels between these findings are suggestive in light of recent evidence that lonely individuals are less likely throughout the day to actively cope and more likely to feel anxious and threatened than non-lonely individuals.”
The second study recruited six men and 19 women, ages 53 to 78, from the community. All of the subjects were generally healthy for their age. The subjects were administered the loneliness questionnaire as well as several medical tests to assess their blood pressure and other clinical measures.
Among the subjects who were deemed lonely, blood pressure was significantly higher in the older half of the group than the younger half. In those who were not lonely, blood pressure was similar across the age range of the group.
These find corroborates the findings from the first study and suggests loneliness is a relatively stable characteristic across the ages, the authors say.
“Lonely individuals tend to perceive their social world as less reinforcing and more threatening generally than non-lonely individuals,” Seeman says.
The study was funded by grants from the John D. and Catherine T. MacArthur Foundation and the National Institutes of Health.
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