The Entorhinal Cortex and Aerobic Exercise in Aging

The overall goal of this study is to examine how regular exercise affects brain function, spatial memory, and virtual navigation. Participation in this research study will take approximately 4 months.

The investigators are examining the effects of exercise and cardiovascular fitness on cognitive processes. Specifically, the investigators are examining if exercise improves brain function in a brain area known as the entorhinal cortex. Together with the hippocampus this brain area is important for memory formation and spatial navigation. Participation in this research study will take approximately 4 months. During this time, participants will make three initial study visits. The first visit is for informed consent and screening, the second visit is for baseline fitness testing, and the third visit is for cognitive testing and a functional MRI exam. Functional MRI is a brain imaging technique that uses a magnetic field to "take pictures" of the brain while a person performs a cognitive task. It will take up to approximately three weeks to complete these initial three study visits. Following the three initial study visits, the exercise-training program will begin. Participants will be randomized to one of two training programs: a cardiovascular endurance-training program (aerobic exercise) and a strength, balance, and flexibility training program (non-aerobic exercise). The exercise training program will last 12 weeks. There will be three one-hour exercise sessions per week. After completion of the exercise-training program, participants will attend two follow-up study visits. The first follow-up visit is for fitness testing. The second follow-up visit is for cognitive testing and an MRI exam.

Eligibility Criteria:
Inclusion Criteria:

* Age between 60-80 years
* Physical inactivity/sedentary status (The American College of Sports Medicine defines a sedentary lifestyle as a lifestyle in which a person is not participating in at least 30 minutes of moderate intensity physical activity on at least three days per week for at least three months.)
* Generally healthy
* Living in the greater Boston area
* Fluent in English (must have attended elementary school and higher in English)
* Non-smoking

Exclusion Criteria:

* Poor vision that cannot be corrected with glasses or contact lenses
* Presence of an acute infection
* Diagnosis of kidney failure
* Diagnosis of liver disease
* Diagnosis of thyrotoxicosis/hyperthyroidism
* Diagnosis of cancer
* Diagnosis of severe anemia
* Past or present conditions that affect cognitive functioning:

  * learning disability
  * neurological disorders or conditions (movement disorder, history of head trauma or stroke, epilepsy, etc.)
  * psychiatric disorders or conditions within last 5 years (depression, anxiety disorder, etc.)
  * Severe stress
* Evidence of cognitive impairment (e.g. dementia)
* Claustrophobia (fear of small, enclosed spaces)
* Obesity
* Past or present conditions that are counter indicators for participation in cardio-respiratory fitness assessment and physical exercise:

  * heart conditions (e.g. heart attack, arrhythmias, etc.)
  * circulatory conditions (e.g. uncontrolled hypertension, leg claudication, high cholesterol, etc.)
  * respiratory conditions (e.g., asthma or lung conditions, such as chronic obstructive pulmonary disease, acute bronchitis, acute common cold, lung cancer, pneumonia, etc.)
  * current musculoskeletal impairments (e.g. fractures, hemiplegia, chronic joint pain, arthritis, osteoporosis, not able to walk comfortably without assistance, etc.)
  * diagnosis of electrolyte disorder or abnormality
  * presence of diabetes mellitus
* Prescription medication or other drugs that treat heart, lung, or circulatory conditions (e.g. beta blockers, bronchodilators, etc.)
* Prescription medication or other drugs that affect chemicals in the brain (e.g. antidepressants, anxiolytics, etc.)
* Drug abuse or alcohol misuse
* Metal in or on the body that cannot be removed (e.g. pacemaker, defibrillator, metal implant that is ferrous)
* Some known abnormal MRI findings (case by case basis)
* Regularly exercising
* Unavailable for the approx. 4-month duration of the study