TUESDAY, March 28, 2006 (HealthDay News) -- Loneliness has now joined obesity and lack of exercise as a potential risk factor for hypertension.
New research shows that loneliness can add 30 points to a blood pressure reading for adults over the age of 50.
The study's results have surprised everyone involved.
"The take-home message is that feelings of loneliness are a health risk, in that the lonelier you are, the higher your blood pressure. And we know that high blood pressure has all kinds of negative consequences," said lead researcher Louise Hawkley, a research scientist at the Center for Cognitive and Social Neuroscience at the University of Chicago.
Her team published its findings in the April issue of Psychology and Aging.
Hawkley said this study was inspired by previous work, published in 2002, that discovered profound and lingering effects of loneliness on the blood pressure of undergraduate college students.
"We thought that if this was maintained over time, it's setting up their systems to develop vascular issues that could lead to hypertension," she said.
So, in this latest study, Hawkley's group interviewed 229 people aged 50 to 68 years of age. They used standard questionnaires to determine each participant's perceived level of loneliness, as well as other psychosocial and cardiovascular risk factors.
The researchers found that lonely older people had blood pressure readings that were as much as 30 points higher than others -- even after other negative emotive states, like sadness, stress or hostility, were taken into account.
A 30-point spread in blood pressure is equal to the difference between a normal diastolic pressure of 120 mm/Hg and stage 1 hypertension, measured at 150 mm/Hg, the researchers pointed out.
What's more, the effect of loneliness in increasing hypertension appeared to get stronger with age, the Chicago team found.
"I was surprised by the magnitude of the effect," said Richard Suzman, associate director of Behavioral and Social Research at the U.S. National Institute on Aging, which helped fund the study.
Hawkley agreed, noting that the effect of loneliness on blood pressure in older individuals is similar to that of physical risk factors long targeted by physicians, such as obesity or sedentary lifestyles.
Hawkley and Suzman were also surprised by the "specificity" of the findings -- that it was loneliness, per se, and not attendant states such as depression or anger, that appeared to be responsible for the boost in blood pressure.
And what about stress?
"Lonely people are stressed, we know that," Hawkley said. However, her team found that stress boosted blood pressure in a way that was distinct from loneliness.
"Its effect was additive," Hawkley noted. "So, that means that people who are lonely have a double whammy -- they are feeling the stress and they are lonely," both of which send blood pressure skyward, she said.
If loneliness can raise blood pressure, then the solution seems easy: strengthen existing relationships and make new ones. But Hawkley -- who has studied loneliness for years -- said it's usually not that simple.
"Remember, people can feel lonely even if they are with a lot of people," she said. "You can think of Marilyn Monroe or Princess Diana -- there was certainly nothing lacking in their social lives, yet they claimed to have felt intensely lonely."
Chronically lonely people also tend to have conflicted emotions when it comes to reaching out to others, Hawkley said.
"They may want to go out and make friends, and yet they have a nagging lack of trust with whomever they want to interact with, or they may feel hostile. So they end up behaving in ways that force the potential partner away," she added.
Targeted interventions that break that cycle might help change things, she said.
Whatever its cause, Hawkley believes loneliness, like obesity and other cardiovascular risk factors, may be on the rise in America. "We have [more] single-parent families, parents living far away from their children, children living far away from each other, and people being transient, not staying put very long," she said.
Suzman stressed the findings need to be replicated before any firm conclusions can be drawn.
However, if the findings do bear out, he believes that "this area is ripe to begin trying out interventions to see how one could change, modulate or reduce the impact of loneliness on blood pressure. If those interventions are low-cost and practical, then it's going to have a significant public health impact."
For more on battling loneliness, head to the University of Iowa.