Inclusion Criteria:  Diagnosis of Probable Alzheimer's Disease, prodromal Alzheimer's Disease, Frontotemporal Dementia, Mild Cognitive Impairment, or Dementia with Lewy Bodies or mild and moderate/severe TBI. Diagnosis of familial or sporadic ALS per El Escorial Criteria or individuals with known gene mutations associated with ALS (regardless of clinical phenotype). Age-matched controls Males and females with a minimum age of enrollment of 18 years. There is no maximum age of enrollment.  Exclusion Criteria:  Primary pulmonary disease such as severe emphysema or asthma not under good medical control. Current sinusitis or common cold or upper respiratory infection, nasal polyps, or sinusitis. Traumatic or congenital anosmia Current or recent (past 6 months) alcohol or substance dependence. A prior history of alcohol or substance abuse will not be grounds for exclusion. Pregnancy Severe cognitive dysfunction Pneumocephalus Basilar skull fracture Known CSF leak Facial fractures to include Lefort I, II or III