Apraxia of speech (AOS) is a motor speech disorder reflecting a problem with the programming and/or planning of speech. AOS is well recognized in the context of stroke where onset is acute and the condition improves or is stable and chronic. AOS that is insidious in onset and progresses over time because of neurodegeneration is less well recognized and understood. For the past decade the investigators have been studying patients with primary progressive apraxia of speech (PAOS). They have demonstrated that it can be the earliest manifestation of an underlying neurodegenerative disease and have recently reported that the profile of PAOS characteristics can differ among affected patients. In some instances, the speech pattern is dominated by distorted sound substitutions and additions, and other features attributable to articulatory difficulty, while in other instances the pattern is dominated by slow, prosodically segmented speech. We have designated the first profile as Phonetic PAOS (Ph-PAOS) and the second as Prosodic PAOS (Pr-PAOS; previously referred to in our studies as type 1 and 2, respectively). Importantly, it appears that the AOS pattern type may have prognostic implications. In a recent longitudinal study, the investigators observed that in some PAOS patients, the AOS remained the most salient feature over an average of seven years of the neurodegenerative disease. Other patients developed a severe extrapyramidal syndrome, resembling progressive supranuclear palsy, within five years, causing significant morbidity, including the inability to ambulate and a shortened life span; interestingly, this more aggressive course was associated with the Pr- PAOS type. At present, little is known about these types. To address the main aim to better understand the neurobiology and clinical associations of PAOS types, they will perform longitudinal speech, language, and neurocognitive testing, acoustic analyses, neuroimaging, and autopsy in a cohort of 47 new PAOS patients (for 80 PAOS patients total) and healthy controls.