10 Surprising Ways to Lose Your Mind

Dementia isn't always irreversible and, in fact, may be treatable, depending on what's causing it. wildpixel/iStock/Thinkstock

Pete began to forget where things were. It bothered him. His memory was worsening. One night, while watching television, he saw a program about Alzheimer's disease. Pete soon realized he had the same symptoms as the man on the TV.

"I tried to relax, not to think about what might be happening to me; but it was there, like the sound of distant thunder, lurking on the horizon. I knew something was wrong, had sensed it for some time, and it was beginning to scare me," he wrote in his shared story for the Alzheimer's Association.

Alzheimer's disease and other forms of dementia occur when people begin to lose the ability to think, to remember and to reason. Sections of the brain key to those activities become riddled with infections or diseases, such as Alzheimer's, which can destroy nerve cells in the brain. Symptoms include changes in mood, personality and behavior. Dementia also can stem from head injuries, serious drug use and several other causes [source: WebMD].