The Effects of an Extensive Exercise Program on the Progression of Mild Cognitive Impairment

Inclusion Criteria: * Diagnosis of mild cognitive impairment (MCI) due to Alzheimer's disease (AD) according to the Albert et al (2011) criteria * Montreal Cognitive Assessment (MoCA) (Nasreddine et al. 2005) score 18-26 * Stable medical condition for more than 6 months * Stable medications for more than 3 months * Adequate visual and auditory acuity to complete neuropsychological testin * Electrocardiogram without significant abnormalities that might interfere with the study * Physical ability sufficient to allow performance of endurance exercise training * Capacity to provide written and dated informed consent form * Medical clearance to undergo a symptom-limited cardiopulmonary exercise test and extensive aerobic exercise training * Participants recruited from the community via newspaper articles and community advertisement will complete additional testing to determine MCI status. Participants must score ≤1.5 standard deviation (SD) of cut-off scores on episodic memory test Exclusion Criteria: * Diagnosis of AD or other type of dementia * History of familial early-onset dementia * Enrollment onto any investigational drug study * History in the past 2 years of epileptic seizures (Participants with epilepsy who have been stable off medication and seizure free for 2 years may be included) * Any major psychiatric disorder (a clinical diagnosis of major depressive disorder, bipolar or schizophrenia) * Past history or MRI evidence of brain damage, including significant trauma, stroke, hydrocephalus, mental retardation, or serious neurological disorder * Carotid stent or severe stenosis * History of myocardial infarction within previous year congestive heart failure (New York Heart Association Class II, III or IV) * Uncontrolled hypertension or hypotension (systolic blood pressure \>200 mm Hg and/or diastolic blood pressure \>110 mm Hg at rest) * Unstable cardiac, renal, lung, liver, or other severe chronic disease * Type 2 diabetes mellitus with hypoglycemia in the last 3 months * Significant history of alcoholism or drug abuse within last 10 years * Significant obesity limiting active participation in the exercise program * Engagement in moderate-intensity aerobic exercise training for more than 30 minutes, 3 times per week, during past 2 years * History of vitamin B12 deficiency or hypothyroidism (stable treatment for at least 3 months is allowed) * Serious or non-healing wound, ulcer, or bone fracture