For years they lived in solitary terror of the light beams that caused searing headaches, the technology that took control of their minds and bodies. They feared the stalkers, people whose voices shouted from the walls or screamed in their heads, “We found you” and “We want you dead.”

When people who believe such things reported them to the police, doctors or family, they said they were often told they were crazy. Sometimes they were medicated or locked in hospital wards, or fired from jobs and isolated from the outside world. But when they found one another on the Internet, everything changed. So many others were having the same experiences.

Type “mind control” or “gang stalking” into Google, and Web sites appear that describe cases of persecution, both psychological and physical, related with the same minute details — red and white cars following victims, vandalism of their homes, snickering by those around them.

Identified by some psychologists and psychiatrists as part of an “extreme community” on the Internet that appears to encourage delusional thinking, a growing number of such Web sites are filled with stories from people who say they are victims of mind control and stalking by gangs of government agents.

Although many Internet groups that offer peer support are considered helpful to the mentally ill, some experts say Web sites that amplify reports of mind control and group stalking represent a dark side of social networking. They may reinforce the troubled thinking of the mentally ill and impede treatment.

Of course. True Believers – scattered, diverse, unconnected – can now gather into into a group reinforcing their shared delusions.

Individual medical care, discussion and mediation, now has yet another counter-current to reality blocking the way. More ways to choose dementia.