Progressive supranuclear palsy (PSP) is a rare brain disorder that causes problems with walking and balance as well as dementia.

About 20,000 North Americans — or one in every 100,000 people over age 60 — have PSP. Patients with PSP are usually middle-age or elderly, and men are affected more often than women. This disease is difficult to diagnose because it is so rare and is sometimes mistaken for Parkinson’s disease.

The signs and symptoms of progressive supranuclear palsy (PSP) vary from patient to patient but loss of balance while walking is the most common first symptom. Patients may have unexplained falls or a stiffness and awkwardness when walking. Sometimes the falls are described as attacks of dizziness, which can lead to an incorrect diagnosis of an inner ear problem. In addition, with PSP speech usually becomes slurred. In rare cases, some patients will experience shaky hands.

Other common early symptoms include a loss of interest in usual hobbies or recreational activities, increased irritability and forgetfulness. Patients may suddenly laugh or cry, be apathetic or have occasional angry outbursts for no apparent reason.

As the disease progresses, many patients develop blurring of vision and problems controlling eye movements. These symptoms are caused by a gradual deterioration of brain cells at the base of the brain in an area called the brainstem. PSP patients have trouble voluntarily shifting their gaze downward and can have trouble controlling their eyelids. This can lead to involuntary closing of the eyes, prolonged or infrequent blinking, or difficulty in opening the eyes.

Another common visual problem is an inability to maintain eye contact during a conversation. This can give the mistaken impression that the patient is hostile or uninterested.

As PSP gets progressively worse, patients are at greater risk for complications, such as pneumonia, head injury and fractures caused by falls. Swallowing solid foods or liquids can be difficult and choking becomes a hazard. The most common cause of death is pneumonia. However, with good medical attention and treatment, many PSP patients live well into their 70s and beyond.

There is currently no effective treatment or cure for PSP, although some of the symptoms can respond to nonspecific measures.