Research published in the Journal of Epidemiology and Community Health found that small number of friends at the age of 45 was linked to lower levels of psychological well-being for both men and women.
The study included more than 6500 Britons born in 1958, all of whom were part of the National Child Development Study (NCDS), when they were aged 42, 45 and 50.
When participants’ psychological well-being was assessed at the age of 50, the results showed a significant association between the number of friends and psychological well-being, the impact of which was greater for women.
Compared with those with 10 or more regular contacts, smaller networks of friends at the age of 45 were associated with significantly lower levels of psychological well-being for both sexes.
These findings were consistent irrespective of whether they had a partner or job or had had a mental-health issue in the past.
Psychological well-being was also influenced by the size of kinship networks for men although to a lesser extent than friendship.
Psychological well-being was especially poor among those with no relatives or friends; among men this was 2.3 points lower if they had no relatives and 2.6 points lower if they had no friends compared with those with 10 or more regular social contacts.
For women, lack of friends had an even greater impact on well-being. This was 4 points lower if they had no friends. But a lack of relatives had no emotional impact.
The study also found that employment had no bearing on the size of social networks, but education did.
Men who left full-time education between the ages of 17 and 19 were 45 per cent less likely to have a larger kinship network, while those staying on until 20 or beyond were 60 per cent less likely to do so.
The comparable figures for women were 17 per cent and 60 per cent, respectively.
Staying on in full-time education after 16 also reduced the size of men’s friendship network, but it increased women’s by 38 per cent if they left between 17 and 19, and by 74 per cent if they left after the age of 20.