Exercise, Age-Related Memory Decline, And Hippocampal Function

Inclusion Criteria:

1. Age 20-75 years
2. English-speaking
3. Ambulatory
4. "Average" fitness as determined by ACSM's Guidelines for Exercise Testing and Prescription (for men, VO2max < 43 for age 20-39 years, < 38 for age 40-49 years, < 35 for age 50-59, < 31 for age 60-75; for women, < 36 for age < 30 years, < 34 for age 30-39 years, < 32 for age 40-49 years, <25 for age 50-59 years, < 24 for age 60-75 years
5. BMI <35

Exclusion Criteria:

1. Ischemic changes or abnormal resting cardiogram, abnormal blood pressure responses, or an significant ectopy during aerobic capacity testing
2. Cardiovascular disease
3. BMI > 35
4. Uncontrolled high blood pressure (systolic blood pressure ≥ 140 mmHg; or diastolic blood pressure ≥ 90mmHg on two measures)
5. Any condition for which aerobic training is counter-indicated, including persons with evidence or history of medical or orthopedic conditions which might make participation problematic.
6. Current or recent (evidence of disease x 5 years) non-skin neoplastic disease or melanoma. Prostatic carcinoma will not be grounds for exclusion.
7. Active hepatic disease (not a history of hepatitis) or primary renal disease requiring dialysis, primary untreated endocrine diseases, e.g., Cushing's disease or primary hypothalamic failure or insulin dependent diabetes (Type I or II). Welltreated hypothyroidism will not be excluded.
8. History of chemotherapy
9. HIV infection
10. Pregnant or lactating (participation allowed 3 months after ceasing lactation).
11. Medications that alter inflammation or autonomic nervous system activity
12. Any history of psychosis or ECT
13. Current or recent (past one year) Major Depressive Disorder, Bipolar Disorder
14. Current or recent (within past 12 months) alcohol or substance abuse or dependence. Recent use (past month) of recreational drugs.
15. Dementia Rating Scale (DRS) score less than 135. Medical History Interview
16. Neurological Disorders Dementia Rating Scale
17. Stroke Telephone screen
18. Alzheimer's Disease Telephone screen
19. Smoking Telephone screen
20. Prior participation in another Dr. Sloan Exercise Study
21. MRI Exclusion Criteria: Cardiac Pacemaker; Internal Pump; Insulin Pump; Tattoo; eyeliner; Wire Sutures; Internal Metal Objects; Metal Slivers in Eye; Prosthesis; Hearing Aid Implants; Neurostimulator; Metal Fragments; Brain Aneurysm Clips; Vascular Clips; Breast Expander; Vena Cava Filter; Heart Valve; Metal Stents; Asthma; Hay-Fever; Sickle Cell Disease; Kidney Disease; Machinist or ever worked with heavy metals Interview; Contraindication to gadolinium, including prior adverse reaction to gadolinium, past or current history of severe breathing difficulty that has been treated by a physician (e.g., asthma, COPD, etc.), and sickle cell disease. History of renal impairment or estimated glomerular filtration rate <30 L/min/1.73m2 is also exclusionary; Machinist or ever worked with heavy metals Interview; Have had more than one MRI scans with Gadolinium