Thequestforneuroprotectivedrugstoslowtheprogressionofneurodegenerativediseases(NDDs),includingAlzheimer'sdisease(AD),Parkinson'sdisease(PD),andHuntington'sdisease(HD),hasbeenlargelyunrewarding.Preclinicalevidencesuggeststhatrepurposingquetiapine,lithium,valproate,fluoxetine,donepezil,andmemantineforearlyandpre-symptomaticdisease-modificationinNDDsmaybepromisingandcanspareregulatorybarriers.Theliteratureofthesepsychotropicsinearlystageandpre-symptomaticAD,PD,andHDisreviewedandpropitiousfindingsfollow.Mildcognitiveimpairment(MCI)phaseofAD:salutaryhumanrandomizedcontrolledtrialfindingsforlow-doselithiumand,inselectedpatients,donepezilawaitreplication.Pre-symptomaticAD:humanepidemiologicaldataindicatethatlithiumreducesADrisk.Animalmodelstudies(AMS)revealencouragingresultsforquetiapine,lithium,donepezil,andmemantine.EarlyPD:valproateAMSfindingsshowpromise.Pre-symptomaticPD:lithiumandvalproateAMSfindingsareencouraging.EarlyHD:uncontrolledclinicaldataindicatenon-progressionwithlithium,fluoxetine,donepezil,andmemantine.Pre-symptomaticHD:lithiumandvalproateareauspiciousinAMS.Manyotherpromisingfindingsawaitingreplication(valproateinMCI;lithium,valproate,fluoxetineinpre-symptomaticAD;lithiuminearlyPD;lithium,valproate,fluoxetineinpre-symptomaticPD;donepezilinearlyHD;lithium,fluoxetine,memantineinpre-symptomaticHD)arereviewed.Dose-andstage-dependenteffectsareconsidered.Suggestionsforsignal-enhancementinhumantrialsareprovidedforeachNDDstage.
