Question: which one of these is not a risk factor for dementia?
Answer: Age. The risk of Alzheimer's disease, vascular dementia, and several other dementias goes up significantly with advancing age.
Genetics/family history. ... 
Smoking and alcohol use. ... 
Atherosclerosis. ... 
Cholesterol. ... 
Plasma homocysteine. ... 
Diabetes. ... 
Mild cognitive impairment.