From the Wikipedia:
Certain drugs have been known to induce hypergraphia including donepezil. In one case study, a patient taking donepezil reported an elevation in mood and energy levels which led to hypergraphia and other excessive forms of speech (such as singing).[9] Six other cases of patients taking donepezil and experiencing mania have been previously reported. These patients also had cases of dementia, cognitive impairment from a cerebral aneurysm, bipolar I disorder, and/or depression. Researchers are unsure why donepezil can induce mania and hypergraphia. It could potentially result from an increase in acetylcholine levels, which would have an effect on the other neurotransmitters in the brain.[9]
From the Mayo Clinic where Andy was denied surgery because of the mail room or something:
Donepezil is used to treat dementia (memory loss and mental changes) associated with mild, moderate, or severe Alzheimer's disease. Donepezil will not cure Alzheimer's disease, and it will not stop the disease from getting worse. However, it can improve thinking ability in some patients.
I'm not one for jumping to conclusions but QED.