Post Traumatic Stress Disorder (PTSD), Sleep Disordered Breathing And Genetics: Effects On Cognition

Inclusion Criteria: 1. Age 55 years or older, male or female veterans of any racial or ethnic group. 2. PTSD subjects will be positive for lifetime PTSD, related to any past lifetime traumatic experience and have a diagnosis of current, chronic PTSD by the Clinician Administered PTSD Scale (CAPS) criteria with current CAPS score \> 40 3. Capable of giving informed consent for the study 4. Sufficient visual and auditory acuity for cognitive testing Exclusion Criteria: Psychiatric Exclusions: 1. Current or lifetime history of any psychiatric disorder with psychotic features 2. Current or lifetime bipolar disorder or delusional disorder 3. Prominent suicidal or homicidal ideation 4. Current exposure to trauma or recent exposure to trauma in the past 3 months. 5. Currently or have within the past six months met DSM-IV criteria for drug or alcohol abuse or dependence (except nicotine). 6. Presence of alcohol intoxication (by breathalyzer) or alcohol withdrawal (by exam) during testing 7. Diagnosis of probable or possible dementia 8. Mini-Mental State Exam (MMSE) \< 23 9. History of seizure disorder. Medical/Medication Exclusions: 1. Acute illness or unstable chronic illness (e.g., history of severe liver disease (cirrhosis, esophageal varices, ascites, portal hypertension, hepatic encephalopathy). Clinical or laboratory evidence of active hepatic disease will be recorded. 2. History of neurologic (e.g., multiple sclerosis, seizure disorder, stroke, history of transient ischemic attacks) or systemic illness affecting central nervous system (CNS) function (e.g. liver failure, kidney failure, congestive heart failure, systemic cancer) 3. Unstable or severe cardiovascular disease 4. Unstable gastrointestinal disorder 5. Uncontrolled hypertension 6. Head injury within one year 7. Loss of consciousness \>24 hrs 8. Use of systemic steroid medication (with the exception of Estrogen replacement therapy which is permissible) 9. Illiterate or unable to read or write English or are judged by the investigator to be unable or unlikely to follow the study protocol 10. Toxicology evidence of illicit substance use.