The latter accounts for some of the falls experienced by these patients, as they find it difficult to look up or down.Some of the other signs are poor eyelid function, contracture of the facial muscles, a backward tilt of the head with stiffening of the neck muscles, sleep disruption, urinary incontinence, and constipation. Some patients retain full cognitive function up to the end.The visual symptoms are of particular importance in the diagnosis of this disorder. Patients typically complain of difficulty reading due to the inability to look down well. The ophthalmoparesis experienced by these patients mainly concerns voluntary eye movement and the inability to make vertical saccades, which is often worse with downward saccades. Patients tend to have difficulty looking down (a downgaze palsy) followed by the addition of an upgaze palsy. This vertical gaze paresis will correct when the examiner passively rolls the patients head up and down as part of a test for the oculocephalic reflex. Involuntary eye movement, as elicited by Bells phenomenon, for instance, may be closer to normal. On close inspection, eye movements called "square-wave jerks" may be visible when the patient fixes at distance. These are fine movements, that can be mistaken for nystagmus, except that they are saccadic in nature, with no smooth phase. Although healthy individuals also make square-wave jerk movements, PSP patients make slower square-wave jerk movements, with smaller vertical components.
Progressive supranuclear palsy (PSP) is a late-onset degenerative disease involving the gradual deterioration and death of specific volumes of the brain. The condition leads to symptoms including loss of balance, slowing of movement, difficulty moving the eyes, and cognitive impairment. PSP may be mistaken for other neurodegenerative diseases such as Parkinsons, frontotemporal dementia and Alzheimers. The cause of the condition is uncertain, but involves accumulation of tau protein within the brain. Medications such as levodopa and amantadine may be useful in some cases.PSP affects about six people per 100,000. The first symptoms typically occur at 60–70 years of age. Males are slightly more likely to be affected than females. No association has been found between PSP and any particular race, location, or occupation. Signs and symptoms
The initial symptoms in two-thirds of cases are loss of balance, lunging forward when mobilizing, fast walking, bumping into objects or people, and falls. Dementia symptoms are also initially seen in about one in five cases of frontotemporal dementia.Other common early symptoms are changes in personality, general slowing of movement, and visual symptoms. The most common behavioural  symptoms in patients with PSP include  apathy, disinhibition, anxiety, and dysphoria.Later symptoms and signs can include, but do not necessarily include dementia (typically including loss of inhibition and ability to organize information), slurring of speech, difficulty swallowing, and difficulty moving the eyes, particularly in the vertical direction.