Assessment of Hyperphosphorylated Tau PET Binding in Primary Progressive Aphasia and Frontotemporal Dementia

Inclusion Criteria: * Must be over the age of 18 * Must speak English as your primary language * Must have an informant who can provide independent evaluation of functioning * Must present with a chief complaint of progressive impairment of speech/language or changes in behavior * Must fulfill diagnostic criteria for Primary Progressive Aphasia or Frontotemporal Dementia Exclusion Criteria: * Any subject who is mute or whose speech is unintelligible will be excluded * All subjects with concurrent illnesses that could account for speech and language deficits, such as traumatic brain injury, strokes or developmental syndromes, and subjects meeting criteria for another neurodegenerative disease, such as amnestic Alzheimer's type dementia, dementia with Lewy bodies, progressive supranuclear palsy, and corticobasal syndrome will be excluded * All pregnant, post-partum and breast-feeding women will be excluded * Subjects will also be excluded if 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). * Subjects who meet criteria for PPA and have mild behavioral changes, eye movement abnormalities or mild limb apraxia but who do not meet diagnostic criteria for, progressive supranuclear palsy or corticobasal syndrome respectively, will also 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.