Patient description: The patient is a 32-year-old obese woman who came to the clinic with weight concerns. She is 165 cm tall and her weight is 113 kg. She is complaining of sleep apnea, PCO and dissatisfaction with her body shape. She is a high-school teacher married for 5 years. She doesn't use any contraceptive methods for the past 4 months and she had no prior pregnancies. She doesn't smoke or use any drugs. She likes to try diets and exercise to lose weight. She completed the four square step test in 14 seconds. Her BP: 130/80, HR: 195/min and her BMI is: 41.54. Her labs: FBS: 98 mg/dl TG: 150 mg/dl Cholesterol: 180 mg/dl LDL: 90 mg/dl HDL: 35 mg/dl Her cardiac assessment is normal. Her joints and ROM are within normal.

Clinical trial eligibility criteria: eligible ages (years): 30.0-75.0,  Obstructive Sleep Apnea Alzheimer's Disease Group A Male and female subjects with normal cognition and 55-75 years of age Newly recruited or recruited on the follow-up evaluation from an existing longitudinal cohort of 180 normal elderly already enrolled in an active study (R01HL118624-01). Group B Male and female subjects with normal cognition and 30-75 years of age Recruited from the MSSM where there are already studies ongoing aimed at determining the consequence of disrupting REM sleep via CPAP withdrawal on the consolidation of spatial navigational memory (PI. Dr. Varga) Previously diagnosed moderate-severe SDB patients and on active CPAP treatment. Group A + B All subjects will be within normal limits on neurological and psychiatric examinations All subjects enrolled will have both a Clinical Dementia Rating (CDR)<0.5 and Global Deterioration Scale (GDS)<3 (i.e. cognitively normal) 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 (s), apolipoprotein E (ApoE) genotyping and DNA banking. B  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 will be excluded. White matter lesions will not be exclusions History of brain tumor or contraindications for LP Prior history of post-LP headache Significant history of alcoholism or drug abuse History of major psychiatric illness (e.g., schizophrenia, bipolar or life long history of major depression) Geriatric Depression Scale >7 (for subjects > 55 y/o) or Beck Depression Inventory >18 (for subjects <55 y/o) Current pregnancy or intent to become pregnant during the period of study Evidence of clinically relevant and uncontrolled cardiac (unstable and untreated coronary or peripheral artery disease), pulmonary (ventilatory failure, Cheyne-Stokes breathing, severe and inadequately controlled arterial hypertension, acute upper respiratory infection), untreated hypothyroid or uncontrolled hematological conditions. Insulin dependent diabetes and/or history of treated hypertension are not exclusions. Normal subjects with current levels of HbA1c >5.9% or diabetics >7.0% and/or current blood pressure levels >140/90 mm Hg will be advised to seek referral Physical impairment of such severity as to adversely affect the validity of psychological testing Any prosthetic devices (e.g., pacemaker or surgical clips) that constitutes a hazard for MRI imaging