Sleep, Aging and Risk for Alzheimer's Disease

Inclusion Criteria: * Male and female subjects with normal cognition and \>50 years of age will be enrolled. Younger subjects are not included as the risk for cognitive impairment is too low. Moreover, by selecting this age-range we minimize the possibility of including early-onset genetic forms of neurodegenerative diseases such as Alzheimer's disease and Frontotemporal Dementia. * Normal subjects will be within normal limits on neurological and psychiatric examinations. All subjects enrolled will have both a Clinical Dementia Rating = 0 and Global Deterioration Scale \< 3. * All subjects will have had a minimum of 12 years education.The education restriction reduces performance variance on cognitive test measures and improves the sensitivity for detecting pathology and disease progression using the robust norms available at NYU School of Medicine. * All subjects will have an informed family member or life partner interviewed to confirm the reliability of the subject interview. All subjects will agree to the MRI imaging, the lumbar puncture, apolipoprotein E (ApoE) genotyping and DNA banking Exclusion Criteria: * Diagnosis of any brain disease or MRI evidence of brain damage including significant trauma, hydrocephalus, seizures, mental retardation or other serious neurological disorder (e.g. Parkinson's disease or other movement disorders). Persons with silent cortical infarcts are excluded. Subcortical infarcts and white matter lesions are not exclusions. * History of br…