The investigators propose a novel treatment strategy that involves Abl inhibition to alter Abeta40/42, total Tau and p-Tau231/181 in subjects with mild to moderate dementia due to AD. The investigators pre-clinical studies show that Nilotinib inhibits brain Abl, decreases Abeta and p-Tau, modulates brain and peripheral immune profiles and reverses cognitive decline in AD models. Taken together, these data support the hypothesis that Nilotinib is a viable therapeutic candidate - via Abl inhibition - in subjects with AD. Based on strong pre-clinical evidence about the effects of Nilotinib on neurodegenerative pathologies, including autophagic clearance of neurotoxic proteins, immunity and behavior, the investigators conducted an open label pilot clinical trial in advanced (stage 3-5) PD with dementia (PDD) and Lewy Body Dementia (LBD) patients. Participants (N=12) were randomized 1:1 to once daily oral dose of 150mg and 300mg Nilotinib for 6 months. The investigators showed that Nilotinib penetrates the blood brain barrier (BBB), in agreement with pre-clinical data. Several studies show that Abeta42 is decreased and CSF total Tau and p-Tau are increased in PD and LBD. Investigators data show that Nilotinib reverses loss of CSF Abeta40/42 and significantly reduces (N=5, P<0.05) CSF total Tau and p-Tau between baseline and 6 months treatment. These biomarker changes are consistent with cognitive improvement (3.5-3.85 points) using Mini-Mental Status Exam (MMSE) and the Scales for Outcomes in Parkinson's Disease-Cognition (SCOPA-Cog) between baseline and 6 months. These data are very compelling to evaluate the effects of Nilotinib in a phase II, randomized, double-blind, placebo-controlled trial in patients with mild to moderate AD.