Habits causing future brain deficits

[Micolusa]

An individual I know has stated that daily and customary habits such as washing, brushing teeth, combing hair, etc., the same way favoring the same hand, leg or side of the body for most of your life can cause dementia, alzheimer', and stroke later in life. Since stroke is caused by ischemic or hemmorhagic damage to the blood vessels in the brain, and it appears that he is completely wrong in this matter, it seems also unlikely that daily life long habits that favor one hand, leg or side of body over another would have a deleterious effect on the brain that would result in dementia or alzheimer's. Is there any truth to his claim? He said that it is a "scientific fact." Thank you for your answer.