It seems that loneliness can make us more “defensive,” which may perpetuate the cycle.

Loneliness makes the areas of the brain that are vigilant for threat more active, a new study finds.

This can make people who are socially isolated more abrasive and defensive — it’s a form of self-preservation.

This may be why lonely people can get marginalised.

Professor John Cacioppo, an expert on loneliness, speaking about an earlier study on the marginalisation of the lonely, said:

“We detected an extraordinary pattern of contagion that leads people to be moved to the edge of the social network when they become lonely.

On the periphery people have fewer friends, yet their loneliness leads them to losing the few ties they have left.

These reinforcing effects mean that our social fabric can fray at the edges, like a yarn that comes loose at the end of a crocheted sweater.”