The precise mechanism of action of donepezil in patients with Alzheimer's disease is not fully understood. Certainly Alzheimer's disease involves a substantial loss of the elements of the cholinergic system and it is generally accepted that the symptoms of Alzheimer’s disease are related to this cholinergic deficit, particularly in the cerebral cortex and other areas of the brain.[13][14] It is noted that the hippocampal formation plays an important role in the processes of control of attention, memory and learning.