| Active, not recruiting | 2/3 | 326 | US | Placebo oral tablet, Placebo, extended release metformin, Metformin | Columbia University, Johns Hopkins University, National Institute on Aging (NIA), University of Rochester, University of Iowa, Boston University, Wake Forest University, Rush University, Pennington Biomedical Research Center, University of Miami, Emory University, Georgetown University, NYU Langone Health, University of California, Berkeley, The University of Texas Health Science Center at San Antonio, University of Washington, State University of New York - Upstate Medical University, University of Texas Southwestern Medical Center, University at Buffalo, University of Cincinnati, Eastern Virginia Medical School, Medical College of Wisconsin, University of Kansas Medical Center, University of New Mexico, Stanford University, University of California, Irvine, Cornell University | Mild Cognitive Impairment | 04/26 | 04/27 | | |
| Active, not recruiting | 2 | 380 | US | Nicotine Transdermal Patch, Placebo Patch | University of Southern California, National Institute on Aging (NIA), Vanderbilt University, Alzheimer's Therapeutic Research Institute | Mild Cognitive Impairment | 09/25 | 09/25 | | |