Alzheimer DiseaseDuodenoscopyBrainCrohn DiseaseParkinson DiseaseAmyloid beta-Peptidestau ProteinsAmyloid beta-Protein PrecursorNeurofibrillary TanglesPlaque, AmyloidApolipoprotein E4DementiaCognition DisordersAmyloid Precursor Protein SecretasesNeuropsychological Testsalpha-SynucleinAmyloidPresenilin-1Antiparkinson AgentsAtrophyDementia, VascularLewy Body DiseaseMild Cognitive ImpairmentNeurofibrilsAge of OnsetApolipoproteins ELewy BodiesNeuronsMental Status SchedulePeptide FragmentsMagnetic Resonance ImagingCase-Control StudiesCognitionLevodopaParkinsonian DisordersPresenilin-2Neurodegenerative DiseasesAgingHippocampusGlucosylceramidaseAspartic Acid EndopeptidasesNerve DegenerationBiological MarkersMice, TransgenicCholinesterase InhibitorsGenetic Predisposition to DiseaseDisease ProgressionMemantinePresenilinsAutopsyDisease Models, AnimalPositron-Emission TomographyCerebral CortexMemory DisordersAniline CompoundsSeverity of Illness IndexParkinson Disease, SecondaryLongitudinal StudiesMutationRisk FactorsGenotypeNational Institute on Aging (U.S.)Cohort StudiesSubstantia InnominataDeep Brain Stimulation