When Paul Kugelman was a kid, he had no shortage of friends. But as he grew older and entered middle age, his social world narrowed.
"It was a very lonely time. I did go to work and I did have interactions at work, and I cherished those," he says. "But you know, at the end of the day it was just me."
Kugelman's story isn't unusual: researchers say it can be difficult for men to hold on to friendships as they age. And the problem may begin in adolescence.