I wonder if loneliness has an effect on the psyche?

We are social animals. Even those who are too shy/apprehensive/socially inept, find outlets, such as the Internet. Sometime, it's hard to tell what comes first, depression or loneliness. At some point though, it becomes a downward spinning cycle, and that of course has a huge effect of the psyche and general health.

In addition to the health/mental issues, lonely people, are vulnerable, as they may be desperate to get out of the loneliness cycle, so they end up doing things that hurt them long term. Nigerian scams depend on it.