Investigating Complex Neurodegenerative Disorders Related to Amyotrophic Lateral Sclerosis and Frontotemporal Dementia

* INCLUSION CRITERIA: Patients will be included if they * Are age 18 or older * Have been given a diagnosis by a neurologist of frontotemporal dementia, primary progressive aphasia, semantic dementia, motor neuron disorder, amyotrophic lateral sclerosis, progressive bulbar palsy, corticobasal syndrome, Huntington disease or other related adult-onset neurodegenerative disorder OR * Carry a mutation in a gene that causes familial ALS or FTD EXCLUSION CRITERIA: Patients will be excluded if they * Have other major neurological or medical diseases that may cause progressive weakness or cognitive dysfunction, such as structural brain or spinal cord disease, metabolic diseases, paraneoplastic syndromes, infectious diseases, peripheral neuropathy or radiculopathy or other significant neurological abnormalities. * Have an unstable medical condition that, in the opinion of the investigators, makes participation unsafe * Require daytime ventilator support at the time of study entry * Are unable to travel to NIH * Patients with pacemakers or other implanted electrical devices, brain stimulators, dental implants, aneurysm clips (metal clips on the wall of a large artery), metallic prostheses (including metal pins and rods, heart valves, and cochlear implants), permanent eyeliner, implanted delivery pumps, or shrapnel fragments, metal fragments in the eye) will not be excluded but will not undergo magnetic resonance imaging. * Patients with tattoos above the neck or permanent make up will be excluded from undergoing 7T MRI.