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Coughing, Sneezing … Loneliness: Isolation Can Make Colds Worse
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If you've got a cold, being around others is likely to blame, but loneliness can actually make your symptoms worse, a new study found.

Researchers found that the lonelier a person feels, the more miserable they are when they have a cold. The researchers noted that people can feel lonely regardless of the number of friends they have.

Previous studies have similarly shown that social connection can play a major role in an individual's health, said John Cacioppo, a professor of psychology at the University of Chicago and co-author of the book "Loneliness: Human Nature and the Need for Social Connection" (W. W. Norton & Company, 2008).

"Loneliness is a major risk factor for poor mental and physical health," Cacioppo, who was not involved in the new research, told Live Science in an email. "About 5 to 10 percent of the population reports feeling lonely frequently or all the time, and an additional 20 to 30 percent report feeling lonely at least sometimes."

In the study, the researchers looked at 213 healthy participants, collecting data on how lonely the participants felt, and the size of their social networks. They also looked at the "diversity" of the participants' networks, meaning the different types of relationships they had, for example, relationships with friends, a spouse, plus co-workers. The participants were then exposed to a cold virus and quarantined in a hotel for five days. Their only social contact came when they passed each other briefly in the hallway. [27 Devastating Infectious Diseases]

Among the participants,159 caught the cold. This subset of participants was nearly 60 percent male, and included people ages 18 to 55 with an average age of 30.

Throughout the five-day period, the participants rated the severity of eight cold symptoms, reporting each day how they’d felt over the last 24 hours. The researchers controlled for several variables (including age, sex, BMI, season of participation and some symptoms of depression), and found that higher levels of loneliness were associated with the reporting of more severe cold symptoms.

The researchers said it was important to note that feelings of loneliness did not affect whether a person became sick. People who said they weren't lonely were just as likely to catch the cold as those who reported a high level of loneliness. The number of people in a participant's social network didn't significantly affect his or her experience of symptoms, either, the researchers found.

In addition, the new study found that the diversity of people’s social networks also didn’t seem to affect how sick they felt, in contrast to previous research that has suggested that more diverse networks are associated with greater resistance to illness.

The study didn't prove a cause-and-effect relationship between loneliness and feeling sicker, the investigators said. But still, previous research has also found that both perceived and actual isolation are factors in health issues. A 2015 meta-analysis published in the journal Perspectives on Psychological Science found that loneliness was linked to a 26 percent increase in people's likelihood of dying during the study period, and that social isolation was linked to a 29 percent increase in this likelihood. [Sniffle Detective: 5 Ways to Tell Colds from Allergies]

The researchers in the new study said their findings suggest that people's perception of isolation may be more powerful than objective social isolation. This perception may affect health through different mechanisms than objective isolation does, Cacioppo said. Researchers are trying to learn more about this, he said.

This new study, he added, aligns with current theories about loneliness and health.

"We have found loneliness is associated with greater use of health care and that loneliness increases self-centeredness (concern about one's own interests and welfare)," Cacioppo said. "This finding is a nice extension of this work."

The researchers said further study is needed that tracks people's levels of loneliness over a longer time span and that focuses on aging populations. These individuals may be more likely to experience both acute illnesses and loneliness, the authors said.

Original article on Live Science.