In Britain and the United States, roughly one in three people older than 65 live alone, and in the United States, half of those older than 85 live alone. Studies in both countries show the prevalence of loneliness among people older than 60 ranging from 10 percent to 46 percent.
While the public, private and volunteer sectors in Britain are mobilizing to address loneliness, researchers are deepening their understanding of its biological underpinnings. In a paper published earlier this year in the journal Cell, neuroscientists at the Massachusetts Institute of Technology identified a region of the brain they believe generates feelings of loneliness. The region, known as the dorsal raphe nucleus, or D.R.N., is best known for its link to depression.
Kay M. Tye and her colleagues found that when mice were housed together, dopamine neurons in the D.R.N. were relatively inactive. But after the mice were isolated for a short period, the activity in those neurons surged when those mice were reunited with other mice.