It might be healthier to go out with your friends instead of cramming for exams in the Reg this weekend, according to a group of University researchers.

A study in the March 2006 edition of Psychology and Aging showed feelings of loneliness may contribute to high blood pressure, which is a risk factor for cardiovascular disease and early death.

“What we found was that the greater the loneliness (i.e. the dissatisfaction with one’s social relationships), the higher the systolic blood pressure,” said Louise Hawkley, a research associate in the Center for Cognitive and Social Neuroscience and one of the study’s authors, in an e-mail interview.

Systolic blood pressure (SBP) is the maximum pressure blood vessels experience when the heart contracts. It is the higher of the two numbers in a blood pressure score.

The study followed a group of 229 adults, ages 50-–68, from around Cook County. Participants were given a survey with 20 loneliness-related questions, such as “How often do you feel close to people?” They also had their blood pressure taken.

The loneliest people had SBPs 30 millimeters of mercury higher than the least lonely study participants. Put in perspective, if a non-lonely person had an SBP of 120, which is the high end of normal, then a similar but lonelier person would have an SBP of 150, which doctors consider Stage 1 Hypertension, or high blood pressure.

Prior studies had shown that other psychological symptoms, such as depression, hostility, and perceived stress, were associated with cardiovascular function, but the U of C team found an independent link between loneliness and SBP even after accounting for these other factors.

The researchers also controlled for ethnicity, age, socioeconomic variables, use of blood pressure medication, and other known risk factors for high blood pressure, but the link remained.

“Loneliness was independently associated with significantly higher levels of SBP,” Hawkley said.

The researchers still aren’t certain that loneliness actually causes high blood pressure, but if further studies do show causation, the team has a couple of ideas why.

Earlier studies have shown that lonely people’s blood vessels have a higher resistance to blood flow because they tend to constrict more. In older people, loneliness might also speed up the natural process of arterial stiffening, thus elevating SBP.

Hawkley described the study as more evidence showing how important social relationships are to health, but she cautioned that just having a lot of friends doesn’t necessarily help.

“Quality counts more than quantity, and it’s good-quality relationships that help protect against feelings of loneliness that could contribute to disease processes,” she said.

“Although having some kind of social life is probably better than not having any at all, it’s really the satisfaction we derive from our social relationships that is important,” Hawkley added.

Hawkley noted that this area is rife for future research. She hopes to look at blood pressure and loneliness data taken over the course of several years to see if loneliness itself causes high blood pressure.

The study was co-authored by Christopher M. Masi, an assistant professor of medicine at the U of C; John T. Cacioppo, a professor in the Department of Psychology at the U of C; and Jarett Berry of the Department of Preventive Medicine at Northwestern.