Loneliness can affect your genes, according to a landmark study in Genome Biology [1] There were differences in the expression of 209 genes in the white blood cells of people experiencing chronic subjective social isolation (loners) compared to those in the blood of people who experience frequent social interaction (party-goers).

Although there is a recognised association between social interaction and health, the paper by professor Stephen Cole of UCLA Medical School shows for the first time the mechanisms behind what makes lonely individuals more prone to the inflammatory response: their genes were affected by particular pathways of transcription factors (which copy DNA to RNA) altering the activity of the genes that are specifically involved in activating the immune system through inflammation; they also have increased numbers of immune cells. Another finding was that even though the lonely individuals were producing slightly higher levels of anti-inflammatory cortisol, the effects of this were down-regulated due to their cortisol receptors not responding properly. Cole describes this as the immune system thinking that the cortisol is "crying wolf".

The adverse health effects of loneliness is not related to the number of friends that a person has, but to how many they think they have. This creates a subjective view of the world that others cannot be trusted, and a perception of the world as relatively more threatening. Now if we could just find the gene that creates the perception of loneliness in a person ...



References

1. Cole SW, Hawkley LC, Arevalo JM, Sung CY, et al. "Social regulation of gene expression in human leukocytes." Genome Biol. 2007 Sep 13;8(9):R189 PMID: 17854483

2. Blog: Genes Get Lonely Too