Science Watch

Going to college challenges the mind and body, not just with the "freshman 15" (pounds) but also, a new study suggests, with a lower immune response for lonely students.

In a study of first-year students--who, data show, tend to visit the student health center more than older classmates--researchers found that social isolation and feelings of loneliness each independently compromised the students' immunity. Ultimately, the combination of loneliness and small social networks weakened immune response the most, suggesting a surreptitious health stressor for shy new students who have yet to build their social circles.

This month's Health Psychology (Vol. 24, No. 3) reports on this multifaceted study, which doctoral candidate Sarah Pressman and health psychologist Sheldon Cohen, PhD, coordinated with fellow scientists through Carnegie Mellon University's Laboratory for the Study of Stress, Immunity and Disease.

The work extends what is known about how our interpersonal relationships can prop up our day-to-day health and outlines the roles played by objective and subjective social factors, say experts. And through examination of a multitude of factors, the study could hint at the mechanism for how social networks affect immunity.

"If lonely individuals are more likely to experience psychological stress or experience it more intensely, which we found, and this stress suppresses immunity, which many studies have shown, then this could be a pathway by which loneliness influences immune response," explains Pressman. The results could have real-world health implications, such as whether social factors help protect us from the flu.

Taking their shots

The study's participants included 37 men and 46 women, most of whom were 18 to 19 years old. These healthy recruits got their first-ever flu shots at a university clinic in the fall of 2000 or 2001. Beyond rolling up their sleeves, they had a lot of other research duties.

First, they filled out a baseline questionnaire on health practices, including information about smoking, alcohol use, sleep patterns and physical activity. Two days before vaccination, each participant began 13 days of ecological momentary assessment. Cued four times a day by a palm computer, students reported their current loneliness, stress and affect. Once a day, they reported on the same health practices measured at baseline. On days two through six (starting the day before the flu shot), participants also collected saliva samples four times a day to measure levels of the stress-hormone cortisol.

To assess loneliness, participants took a short version of the UCLA Loneliness Scale at baseline and during follow-up; daily reports indicated how much they felt "lonely" and "isolated." Researchers averaged them into a single total loneliness score.

To gauge social isolation, participants wrote the initials of up to 20 people that they knew well and were in contact with at least once a month within three concentric circles, indicating closeness by centrality. The total number of initials added up to social-network size.

For 14 weeks following the last day of the self-reports, participants answered biweekly questionnaires that assessed loneliness, stress and mood. Finally, the researchers drew blood samples at baseline (right before the flu shot) and at one and four months after to measure antibody levels--the linchpin of the study. Antibody levels would indicate how well students' immune systems mounted a response to the multistrain flu vaccine, which in 2000 and 2001 included three antigens, or watered-down flu bugs: A/New Caledonia, A/Sidney, and B/Yamanashi (2000) or B/Victoria (2001).

About the study's methodology, Christopher Coe, PhD, a health psychologist at the University of Wisconsin-Madison, comments, "These types of studies are very difficult to conduct, both because of the multidisciplinary nature of the measures and the challenges of a prospective, longitudinal design."

But, says Margaret Kemeny, PhD, director of the health psychology program for the University of California, San Francisco, psychiatry department, the investigators use a more ecologically valid approach than usual: "This approach is much more likely to capture moment-to-moment 'real' experience than other questionnaire methods commonly used in this field."

Reduced responsiveness

The researchers looked for correlations between and among loneliness, network size and immune response. First, they found that sparse social ties (four to 12 contacts instead of 13 to 20) were associated with poorer immune response to one component of the vaccine, A/Caledonia. This association was independent of feelings of loneliness.

Loneliness was also associated with a poorer immune response to A/Caledonia as late as four months after the shot, supporting the argument that chronic feelings of loneliness help predict health and well-being.

The researchers speculate that the reason lonelier and more isolated students showed a weaker response to only one of the vaccine's four viruses--A-type viruses--is that A-type viruses show more "antigenic drift." They mutate more easily and cause more infection, which may play a role in individual variation in response.

The independent associations of isolation and loneliness with immune response were not a surprise to the researchers because social-network size did not correlate with a person's sense of loneliness.

"You can have very few friends with whom you speak regularly but still have no feelings of loneliness," explains Pressman. "Alternatively, there were individuals with many friends who still felt lonely."

Adds Arthur Stone, PhD, vice-chair of the psychiatry department at Stony Brook University of the State University of New York and editor of Health Psychology: "The real-time measures paid off handsomely because unlike the standard measure [recall of loneliness, which is subject to recall bias], they showed association with antibody responses."

Collecting salivary cortisol as students went through their days, Stone notes, also gave a "dynamic view of hypothalamic-pituitary-adrenal axis function over days, enabling new associations to be detected."

The students' immune responses did not correlate with three other measures: stress hormone as measured in salivary cortisol, health behaviors, such as exercise or alcohol consumption, and personality variables such as extroversion or hostility. Only perceived stress--the students' daily self-reported sense of feeling "overwhelmed" and "stressed"--mediated the relationship between loneliness and antibody production. However, perceived stress did not mediate the relationships between isolation and antibody response.

Future research may also look closely at sleep behaviors, which have been associated with immune suppression and, in this study, associated with loneliness.

All the lonely people

The loneliest students with smallest social networks had the smallest antibody response. Thus the researchers speculate that number of ties and loneliness may have some sort of synergistic effect, operating by a common mechanism.

Kemeny comments, "This study makes a very important contribution by showing that the feeling of being alone may be an important predictor of immune competence, irrespective of whether one is actually alone or not."

Certified nurse practitioner Anita Barkin, DrPH, a co-author of the study and director of Carnegie Mellon's Student Health Service, says she's not surprised by the finding, given that she and her colleagues have noted that "students who are lonely and feel less connected and supported seem to visit health services more frequently. They also appear to have longer recovery times when they experience acute, episodic illness."

Social factors are important for health, Pressman continues, because they may encourage good health behaviors such as eating, sleeping and exercising well, and they may buffer the stress response to bad things.

"In college students undergoing a stressful period of adjustment without this social buffer, the stress of the experience is amplified," she explains. "Beyond that, the experience of loneliness is likely a stressful experience by itself."

To help boost the health of the incoming class, Pressman thinks that colleges can encourage students to join clubs, sports teams or volunteer groups to lower isolation and meet people with common interests, raising the odds of friendship.

"Often, a few quality relationships are enough to alleviate loneliness," she says. Having more social roles--for example, student, volunteer, club member and so on--is also better for one's health.

Stone speculates that further research on the impact of changes in loneliness could support the Carnegie Mellon findings and lead to clinical interventions that target loneliness. That could be particularly beneficial to the other end of the age spectrum as well, speculates Pressman.

"As you get older, your immune-system function decreases, and it's not uncommon for the elderly to be relatively isolated and lonely," she says. Thus, researchers might see similar effects of social factors on vaccine response among older people--only stronger because it's harder for them to mount a full vaccination response in the first place.

Rachel Adelson is a science writer in Raleigh, N.C.