Both diseases share other features: onset in late middle age, bradykinesia (slow movement), and rigidity of muscles.
Tremor, very common in individuals with Parkinson's disease, is rare in PSP.
Currently there is no effective treatment for PSP, but some symptoms can be managed with medication or other interventions.
Speech usually becomes slower and slurred and swallowing solid foods or liquids can be difficult.
Other symptoms include slowed movement, monotone speech, and a mask-like facial expression.
The protein tau is associated with microtubules – structures that support a nerve cell’s long processes, or axons, that transmit information to other nerve cells.
The accumulation of tau puts PSP in the group of disorders called the tauopathies, which also includes other disorders such as Alzheimer’s disease, corticobasal degeneration, and some forms of frontotemporal degeneration.
Symptoms of PSP begin on average after age 60, but may occur earlier. PSP was first described as a distinct disorder in 1964, when three scientists published a paper that distinguished the condition from Parkinson's disease.
Estimates vary, but only about three to six in every 100,000 people worldwide, or approximately 20,000 Americans, have PSP—making it much less common than Parkinson's disease (another movement disorder in which an estimated 50,000 Americans are diagnosed each year).People with PSP usually stand exceptionally straight or occasionally even tilt their heads backward (and tend to fall backward).This is termed “axial rigidity.” Those with Parkinson's disease usually bend forward. The disorder’s long name indicates that the disease worsens (progressive) and causes weakness (palsy) by damaging certain parts of the brain above nerve cell clusters called nuclei (supranuclear). One of the classic signs of the disease is an inability to aim and move the eyes properly, which individuals may experience as blurring of vision. The disease results from damage to nerve cells in the brain. Progressive supranuclear palsy (PSP) is an uncommon brain disorder that affects movement, control of walking (gait) and balance, speech, swallowing, vision, mood and behavior, and thinking.