Inclusion Criteria:
* Must be over 35 years of age and present with gradual progression of PSP-related symtoms
* Must have an informant or study partner that can provide independent information of functioning.
* Must meet criteria for possible or probable Progressive Supranuclear Palsy. To fulfill criteria for possible PSP, subjects must have a gradually progressive disorder with either vertical (upward or downward) supranuclear palsy or both slowing of vertical saccades and prominent postural instability with falls in the first year of disease onset. To fulfill criteria for probable PSP, subjects must have vertical (upward or downward gaze) supranuclear palsy and prominent postural instability with falls in the first year of disease onset.
Exclusion Criteria:
* Subjects will be excluded if they meet criteria for another neurodegenerative disease (including corticobasal syndrome, frontotemporal dementia, primary progressive aphasia, Alzheimer's disease, multiple system atrophy and Parkinson's disease) or do not have the symptoms necessary to fulfill inclusion criteria for possible PSP.
* Subjects with concurrent illnesses that could account for their symptoms, such as traumatic brain injury, encephalitis, strokes or developmental syndromes will be excluded.
* Women that are pregnant or post-partum and breast-feeding will be excluded.
* Subjects will be excluded from the study if they have any of the following genetic conditions which can increase the chance of cancer: Cowden disease, Lynch syndrome, hypogammaglobulinemia, Wiskott-Aldrich syndrome, and Down's syndrome.
* Subjects will also be excluded if MRI is contraindicated (metal in head, cardiac pace maker, e.t.c.), if there is severe claustrophobia, if there are conditions that may confound brain imaging studies (e.g. structural abnormalities, including subdural hematoma, intracranial neoplasm or large cortical infarcts), or if they are medically unstable or are on medications that might affect brain structure or metabolism (e.g. chemotherapy).
* Subjects will also be excluded if they do not have an informant, or do not consent to research.
