Safety, Tolerability and the Effects on Cerebrospinal Fluid Spectrin Breakdown Product-145 Levels of ABT-957 in Subjects With Mild Alzheimer's Disease and Mild Cognitive Impairment

* Female participants must have negative results for pregnancy test performed on a serum sample obtained at Screening * Body Mass Index is 18.0 to 35.0 at Screening * Meets the National Institute on Aging and the Alzheimer's Association (NIA-AA) criteria for probable Alzheimer's disease (AD). * Meets the NIA-AA core clinical criteria for Mild Cognitive Impairment due to AD

* Use of any strong inhibitors of drug metabolizing enzymes within 30 days prior to study drug administration * Consumption of alcohol within 24 hours prior to study drug administration * Positive screen for non-prescribed drugs of abuse or alcohol * The participant has clinically significant abnormal laboratory values at Screening as determined by the investigator * History of a drug or alcohol abuse within 6 months prior to study drug administration * Current diagnosis of major depression or other major psychiatric disorder