== Årsager ==
1-5 % af alle tilfælde af Alzheimers kan tilskrives genetiske forskelle, men i langt de fleste tilfælde kendes den reelle årsag ikke.<ref>{{cite web|url=http://www.alz.org/research/science/alzheimers_disease_causes.asp|title=What We Know Today About Alzheimer's Disease|publisher=Alzheimer's Association|access-date=1. oktober 2011|quote=While scientists know Alzheimer's disease involves progressive brain cell failure, the reason cells fail isn't clear.|archive-date=24. december 2018|archive-url=https://web.archive.org/web/20181224221504/http://www.alz.org/research/science/alzheimers_disease_causes.asp|url-status=live}}</ref><ref>{{Cite journal|last=Reitz|first=Christiane|last2=Mayeux|first2=Richard|date=2014-04-15|title=Alzheimer disease: Epidemiology, Diagnostic Criteria, Risk Factors and Biomarkers|journal=Biochemical Pharmacology|volume=88|issue=4|pages=640–651|doi=10.1016/j.bcp.2013.12.024|issn=0006-2952|pmc=3992261|pmid=24398425}}</ref> Denne usikkerhed har givet plads til flere konkurrerende [[hypotese]]r om, hvad sygdommen skyldes:
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