A Study to Evaluate the Safety, Tolerability and Pharmacokinetics of ABT-126 in Subjects With Alzheimer's Disease on Stable Doses of Acetylcholinesterase Inhibitors

This is a double-blind, placebo-controlled, randomized, multiple-dose, parallel group, multicenter study. Up to 20 male and female subjects with mild to moderate Alzheimer's disease (AD) who are taking stable doses of acetylcholinesterase inhibitors will be enrolled in this study. The study will be conducted in up to four sites. Within 28 days prior to study drug administration, subjects will be screened based on National Institute of Neurological and Communicative Disorders and Stroke/Alzheimer's Disease and Related Disorders Association (NINCDS/ADRDA) criteria for probable AD, Mini-Mental State Examination (MMSE) and Modified Hachinski Ischemic Scale (MHIS) scores, medical history, physical examination, neurological examination, vital signs, ECG, laboratory tests and response to Columbia-Suicide Severity Rating Scale (C-SSRS).

Subjects will be divided into two groups of 10 subjects each. In each group, 8 subjects will receive ABT-126 and two subjects will receive matching placebo. Group 1 will be administered Dose 1 of ABT-126 or placebo. Group 2 will be administered Dose 2 ABT-126 or placebo. All doses will be administered once daily in the morning for 10 days.