Exercise for Walking Problems in MCI and Alzheimer's

Inclusion Criteria: * AD and MCI will be defined through formal diagnosis provided by a board-certified Neurologist. Amnestic MCI will be defined using the AD Neuroimaging Initiative (ADNI) criteria. All MCI participants in ADNI are required to have an amnestic subtype defined as: * Subjective memory concern or a memory problem noted by their partner * Abnormal memory function documented by a specified education adjusted cutoff score on the delayed paragraph recall of the Anna Thompson story of the Logical Memory subtest from the Wechsler Memory Scale-Revised * Mini-Mental State Exam (MMSE) score between 20 and 26 (inclusive). Exceptions may be made for subjects with less than 8 years of education at the discretion of the PI. (iv) Single or multi-domain amnestic MCI (both subtypes are at high risk for progression to AD) * Clinical Dementia Rating (CDR) = 0.5 (Memory Box score must be at least 0.5) * General functional performance sufficiently preserved * Evidence of impaired executive function based on Montreal Cognitive Assessment (MoCA) score 13-17 * Able to walk 10 or more feet without an assistive device * Completed six grades of education or has a good work history (sufficient to exclude intellectual disabilities) * Not hospitalized within the last 60 days Exclusion Criteria: * Acute medical illness requiring hospitalization * Uncontrolled congestive heart failure * History of stroke * Inability to perform study procedures * Medical or physical conditions that would preclude participation or walking (e.g., severe arthritis or mobility problems, uncontrolled hypertension or diabetes, renal failure, history of angina with activity) * On medications that could adversely affect cognition, eg: antipsychotics, opioids, stimulants, chemotherapy, anti-parkinsonian drugs (eg Levodopa), neurologic prescriptions to treat Multiple sclerosis and/or Parkinson's * Psychotic disorders * Confounding neurologic conditions (e.g., active central nervous system (CNS) opportunistic infections, seizure disorders, head injury with loss of consciousness \>30 minutes, intracranial neoplasms, stroke with neurological or neuropsychiatric sequelae) * Substance Use Disorder, Major Depressive and Generalized Anxiety Disorders within six months of evaluation