By Christian Jarrett

Already substantial evidence suggests that feeling lonely – regardless of whether we actually are socially isolated based on our number of relationships – is bad for our health, affecting our odds of developing heart disease and other chronic conditions. A new study in Health Psychology extends this literature by showing that feelings of loneliness, but not levels of social isolation, seem to increase the toll of acute illness, in this case by worsening the subjective experience of having a cold.

The researchers, led by Angie LeRoy at the University of Houston and Rice University, said their findings could be useful for helping doctors understand their patients’ different experiences of short-term illnesses. It also provides yet more evidence for why interventions aimed at reducing loneliness need to focus on quality not quantity of social interaction – after all, it’s perfectly possible to feel intensely alone in a crowded room.

This isn’t the kind of study you’d consider volunteering for lightly: the researchers used viral nasal drops to try to infect 159 healthy US participants, average age 30, with a cold (75 per cent became infected) and then they holed them up in quarantine in a hotel for five days. Thankfully for the participants, they received just over $1000 in compensation.

Each day, the participants answered questions about their mood and the severity of eight different cold symptoms, from congestion to chills. They also filled out a loneliness questionnaire at the start, which tapped their subjective sense of loneliness (typical items included “In general, how often do you feel left out?”), and an objective measure of their social isolation based on the number of people they had contact with every two weeks.

Feeling lonely didn’t affect risk of infection by the cold virus, but of the participants who were infected, the more lonely they said they felt, the worse they reported their cold symptoms to be. This remained true when factoring out the influence of negative mood, which was also associated with experiencing more severe symptoms. Social isolation, measured objectively, was not associated with the subjective severity of cold symptoms. “Put simply,” the researchers said, “lonelier people feel worse when they are sick than less lonely people”.

There are some study limitations to be aware of: for instance, loneliness was only measured once, rather than as a dynamic state; deliberate infection isn’t exactly the same process as being infected in everyday life; and we can’t tell from these findings that loneliness causes worse subjective symptoms: some other unmeasured factor, such as lack of sleep, might be the key causal factor (loneliness tends to lead to sleep disruption).

Nonetheless, the results hint at how subjective feelings of loneliness can become self-fulfilling through increasing the sense of feeling unwell after catching a cold, thus driving yet further social withdrawal. This form of negative spiral is in addition to self-perpetuating psychological processes identified by prior research, such as the increased sensitivity lonely people have for social threat. The good news is that by becoming aware of these self-perpetuating mechanisms we can hopefully intervene more effectively and with greater understanding, either to help ourselves or others who feel alone.

—Loneliness predicts self-reported cold symptoms after a viral challenge

Image under licence via Gettyimages.co.uk

Christian Jarrett (@Psych_Writer) is Editor of BPS Research Digest