Aricept contains the active drug donepezil, which is classified as an acetylcholinesterase inhibitor. It's used to treat dementia due to Alzheimer's disease. Aricept is not a psychotropic drug.
Prescription medication yielding a positive drug screen are acceptable except for tricyclic antidepressants (e.g. Amitriptyline, Amoxapine, Desipramine, (Norpramin) Doxepin, Imipramine (Tofranil), Nortriptyline (Pamelor), Protriptyline (Vivactil), Trimipramine (Surmontil)).
Donepezil (Aricept) is NOT an approved medicine for the Phase 2b/3 trial and it was removed as an approved medicine for the Phase 2a Blarcamesine trial.
It is considered unethical to required patients to stop taking SOC when part of clinical trial of an unapproved drug.
Too bad it's not considered unethical to require a placebo control arm for AD, PD, MS and ALS trials when there's ample evidence of placebo effect in a multitude of past trials. We can only hope that External Control Arms will soon be accepted for the same ethical reasons you state. I believe the FDA has recently adopted ECAs for oncology.