ACHE and Alzheimer disease: Donepezil (Figure 2), one of the key drugs used in therapy for treating AD shows a high affinity for S1R (Ki = 14.6 nM) [19], although its main mechanism of action relies on inhibition of acetylcholinesterase (AChE), increasing the concentration of acetylcholine (ACh) at the synaptic level and thus restoring the cognitive functions in AD patients [20].