"Researchers discovered that for people who carry a specific genetic variation -- the K-variant of butyrylcholinesterase, or BChE-K -- donezpezil could accelerate cognitive decline."

Journal Reference:

Louis De Beaumont, Sandra Pelleieux, Louise Lamarre-Theroux, Doris Dea, Judes Poirier.

Butyrylcholinesterase K and Apolipoprotein E-e4 Reduce the Age of Onset of Alzheimer’s Disease, Accelerate Cognitive Decline, and Modulate Donepezil Response in Mild Cognitively Impaired Subjects.

 Journal of Alzheimer's Disease, 2016; 54 (3): 913 DOI: 10.3233/JAD-160373