Only the lonely - genomically speaking

Scientists in America may have found out why loneliness is linked to health problems.

Writing in the journal Genome Biology, Steve Cole and his colleagues collected blood samples from 14 volunteers who had been matched for age, health status, weight, and medication use.

The only difference was that six of the subjects scored in the top 15% on a UCLA Loneliness Scale. The rest of the group were in the bottom 15% on the same scale.

The team analysed the blood samples to study patterns of gene expression from the 14 subjects and found 209 genes that were consistently differently expressed between the lonely and the contented subjects. Of those 209 genes, 78 were genes that were more active, and 131 were genes that were less active.

"White blood cell gene expression appears to be remodelled in chronically lonely individuals," said Cole.

This finding might explain why people who feel socially isolated tend to have a higher risk of certain diseases such as heart disease, high blood pressure, and susceptibility to infections and cancer compared with individuals with a stronger social network.

"These findings provide molecular targets for our efforts to block the adverse health effects of social isolation," says Cole. But the health-promoting effect of friends isn't just down to how many people you know.

"We found that what counts at the level of gene expression is not how many people you know, it's how many you feel really close to over time."

In the future Cole suggests that doctors might be able to use the team's genetic fingerprint of loneliness to monitor the effect of interventions intended to reduce the impact of a poor social network on health.