Definition of Pick's disease:

Pick's disease is a rare and permanent form of dementia that is similar to Alzheimer's disease, except that it tends to affect only certain areas of the brain.

Causes, incidence, and risk factors:

People with Pick's disease have abnormal substances (called Pick bodies and Pick cells) inside nerve cells in the damaged areas of the brain.

Pick bodies and Pick cells contain an abnormal form of a protein called tau. This protein is found in all nerve cells. But some people with Pick's disease have an abnormal amount or type of this protein.

The exact cause of the abnormal form of the protein is unknown. A gene for the disease has not yet been found. Most cases of Pick's disease are not passed down through families.

Pick's disease is rare. It is more common in women than men. It can occur in people as young as 20, but usually begins between ages 40 and 60. The average age at which it begins is 54.