Progressive supranuclear palsy is a disorder characterized by symptoms similar to Parkinson's disease (including unsteady gait, stiff movements, and mild dementia). Other similar disorders include dysfunction of the cerebellum, multiple system atrophy, and senile dementia (Alzheimer's type).

The cause of the damage to the brain cells in this condition is unknown, but the disease is degenerative (gets worse over time). Progressive supranuclear palsy involves damage to multiple cells of the brain, with loss of the myelin sheath (the covering of the nerve cell that speeds nerve impulse conduction) in some nerves and destruction of the entire nerve in other areas.

People with this condition have deposits in brain tissues that resemble the deposits found in Alzheimer's disease. There is atrophy (loss of tissue) in most areas of the brain. The disorder is most often seen in people over 60 years old, and is somewhat more common in men.