PiB PET Scanning in Speech and Language Based Dementias

Inclusion Criteria: * Over the age of 18 * Has an informant/study partner who will be able to provide independent evaluation of functioning * Speaks English as their primary language (including bilingual patients whose primary language is English) * Fulfills diagnostic criteria for PPA (Primary Progressive Aphasia) or Progressive Apraxia of Speech * Agrees to and is eligible to undergo MRI and PET scanning * If woman of child bearing age, pt must agree to pregnancy test no more than 48 hours before the PET scans Exclusion Criteria: * Any concurrent illnesses that could account for speech and language deficits, such as: * traumatic brain injury, strokes and developmental syndromes * patients meeting criteria for another neurodegenerative disease (Alzheimer's Disease, Dementia with Lewy Bodies, behavioral variant frontotemporal dementia, progressive supranuclear palsy, corticobasal degeneration) * Women who is pregnant or post-partum and breast-feeding * Patients for which MRI is contraindicated (metal in head, cardiac pace maker, etc.), if there is severe claustrophobia, if there are conditions that may confound brain imaging studies (e.g. structural abnormalities, including subdural hematoma or intracranial neoplasm), or if they are medically unstable or are on medications that might affect brain structure or metabolism,(e.g. chemotherapy) * Patient is mute (secondary to dysarthria only)