ACHE and Cognitive impairment: To compensate for the loss of cholinergic neurons, drugs that enhance cholinergic transmission were developed as treatments for mild cognitive impairment (see [18]); the most common have been acetylcholinesterase (AChE) inhibitors, starting with tacrine in 1989 and now superseded by drugs such as Aricept (donepezil) and galantamine [19], which prolong the availability of ACh by impeding its metabolism.