AD-4833/TOMM40_303 Extension Study of the Safety and Efficacy of Pioglitazone to Slow Cognitive Decline in Participants With Mild Cognitive Impairment Due to Alzheimer Disease

Inclusion Criteria: 1. Completed the pivotal AD-4833/TOMM40\_301 study with an adjudicated diagnosis of mild cognitive impairment (MCI) due to Alzheimer's Disease (AD) without ongoing serious adverse events (SAEs) from AD-4833/TOMM40\_301. 2. Is male or female and is at least 65 years of age at the time of the Baseline Visit. 3. In the opinion of the investigator, is capable of understanding and complying with the protocol requirements. 4. The participant or, when applicable, the participant's legally acceptable representative signs and dates a written, informed consent form and any required privacy authorization prior to the initiation of any study procedures. 5. Must be living independently or in nonmedical residential care. 6. Has a project partner able to separately consent on his/her own behalf and take part in the study (with the intent to do so as long as the participant is enrolled), providing information on the cognitive, functional, and behavioral status of the participant and assisting with observation of adverse events (AEs) and monitoring of study medication, if needed. Project partners participating in the pivotal AD-4833/TOMM40\_301 study are encouraged to participate in this extension study in this capacity. Exclusion Criteria: 1. Completed the pivotal AD-4833/TOMM40\_301 study with an adjudicated diagnosis of AD dementia. 2. Has a current diagnosis of significant psychiatric illness, per Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (including but not limited to major depressive disorder, anxiety disorders) and is in an acute phase/episode, or the participant has a current diagnosis or history of schizophrenia or bipolar disorder. 3. Has a glycosylated hemoglobin (HbA1c) \>8% at the extension study Baseline Visit or requires treatment with insulin, triple oral antidiabetic therapy or a peroxisome proliferator-activated receptor gamma (PPAR-γ) agonist. 4. Has a clinically significant unstable illness, for example, hepatic impairment or renal insufficiency, or cardiovascular, pulmonary, gastrointestinal (including s/p gastric bypass surgery), endocrine, neurological, rheumatologic, immunologic, infectious, skin and subcutaneous tissue disorders, or metabolic disturbance. 5. Is an immediate family member, study site employee, or is in a dependent relationship with a study site employee who is involved in conduct of this study (eg, spouse, pivotal, child, sibling) or may consent under duress. 6. Is required to take excluded medications. 7. Has a history of hypersensitivity or allergies to pioglitazone or related compounds. 8. Had any of the following values at the extension study Baseline Visit: 1. A serum total bilirubin value \>15 x upper limit of normal (ULN). 2. A serum alanine aminotransferase (ALT) or aspartate aminotransferase (AST) value \>2 x ULN. 3. Unexplained microscopic/macroscopic hematuria on 2 repeat examinations within 2 weeks. 9. Has a disease or takes medication that, in the opinion of the investigator, could interfere with the assessments of safety, tolerability, or efficacy, or prevent the participant from adequately participating in the study or continue for the anticipated duration of the study. 10. Has received any investigational compound, with the exception of treatment during the AD-4833/TOMM40\_301 study, within 30 days prior to Baseline or 5 half-lives prior to Baseline or is currently participating in another study that entails the administration of an investigational or marketed drug, supplement, or intervention including, but not limited to diet, exercise, lifestyle, or invasive procedure. 11. Has any cancer that has been in remission for less than 2 years from the extension study Baseline Visit. Participants with basal cell or stage I squamous cell carcinoma of the skin will be eligible. Participants with current diagnosis of bladder cancer are not eligible irrespective of the remission status. 12. Has a current diagnosis of macular edema, degeneration or any maculopathy. 13. Has a history or current diagnosis of congestive heart failure (CHF), New York Heart Association class III-IV.