Finding and maintaining good friendships is essential to a healthy life. But with busier-than-ever schedules more people are turning to online social networking sites to connect with people who share their same interests and perhaps even live in their community.

Would that active mother of three who, according to her Facebook page, likes to knit and discuss books and who lives near you make a good friend? Should you join that group of triathletes at your gym who meet for regular training and who post their activities and opinions online?

Psychologists say you can weed out potentially unhealthy friendships by observing how others post about themselves on social networking sites, including the most popular of all, Facebook. Parents can even ferret out potentially unhealthy behaviors in their own children and others just by examining their Facebook pages.

In fact, you can determine from the number of Facebook friends and wallposts on any person’s page how narcissistic that person may be. The higher the level of narcissism, the more likely this person is to engage in shallow relationships, say researchers at the University of Georgia who published their analysis of personality types on Facebook in Personality and Social Psychology Bulletin.

For example, narcissists tend to post glamorous, self-promoting pictures while folks with healthier self-esteem are more likely to use casual snapshots. Narcissism is a trait of particular interest because it hampers the ability to form healthy, long-term relationships, says lead researcher W. Keith Campbell, PhD. "Narcissists might initially be seen as charming, but they end up using people for their own advantage," says Campbell, an associate professor at the University of Georgia in Athens.

In fact, the long-term health implications of narcissism include anxiety and anger that often lead to abusive and dysfunctional relationships and loneliness. Left unchecked, narcissism can lead to violence, pornography and sexual fantasy addictions, alcohol and drug addictions and depression.