Washington: How many "close friends" do you have? Well, it could be no more than two who you consider as your best buddies, says a new study.

The Cornell University study found that the list of close friends of Americans has now shrunk to two, down from three confidantes 25 years ago.

But, the number of socially isolated people, or those who have zero confidantes, has not increased over these decades as suspected, found the study.

"Although this shrinking social network makes us potentially more vulnerable, we're not as socially isolated as scholars had feared," study researcher Matthew Brashears was quoted as saying .

"Rather than our networks getting smaller overall, what I think may be happening is we're simply classifying a smaller proportion of our networks as suitable for important discussions," Brashears said.

"This is reassuring in that it suggests that we're not becoming less social."

For their study, Brashears and his team surveyed over 2,000 adults ages 18 and older from an online national representative programme conducted between April and May 2010.

Participants were asked to list the names of people they had discussed "important matters" with over the previous six months. If respondents said "none," they asked whether this was because they didn't have any important matters to discuss or no one with whom to discuss them in the past six months.

About 48 per cent of participants listed one name, 18 per cent listed two, and roughly 29 per cent listed more than two names for these close friends.

On average, participants had 2.03 confidantes. And just over 4 per cent of participants didn't list any name.

When the researchers looked closer at that number of socially isolated individuals, they found that 64 per cent indicated that this was because they had no topic to discuss, while only about 36 per cent had no one to talk to.

It was also found that female participants and those who were educated were the least likely to report no names on their confidante list.

The finding is concerning, said Brashears. "Discussion partners provide both emotional support and ideas for how to solve problems, so a shrinking discussion network may lead to more stress and poorer outcomes," he added.