The Entorhinal Cortex and Aerobic Exercise in Aging

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.

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