"The Obsessive-Compulsive-Disorder brain shows abnormalities in the basal ganglia, where part of the sensory information is coordinated. OCD patients become chronic doubters and cannot trust their own senses.
...
Probably the most impressive demonstration that OCD is a physical affliction was unwittingly carried out by a 22 year old man who compulsively washed his hands hundreds of times a day. This made his life so unbearable that he decided to kill himself. Remarkably, he not only survived the self inflicted gun shot wound to his head, but cured himself of his compulsion. Apparently he had blown away the diseased part of his brain...."- Chemistry of Drugs

This made my day. How sickeningly funny.