Stone has a history of alcohol and drug abuse so if he is showing signs of dementia, it could be the result of that. Substance abuse or dementia does not make one a Holocaust denier or anti-Semite. Those problems may impair inhibitions and allow suppressed thoughts to be expressed.
Yemen's Houthi rebels commit to peace plan in letter to UN chief, BBC reports (Haaretz)
from the article: Oliver Stone apologizes for saying Jews control the media