It is tiresome how many products are marketed with baseless claims of preventing dementia.  Some pushback:

NY Times: Supplements Won’t Prevent Dementia. But These Steps Might.

An excerpt:

The Food and Drug Administration estimates that 80 percent of older adults rely on dietary supplements, many purporting to prevent or treat Alzheimer’s and other forms of dementia…

Vitamins, various antioxidants, concoctions derived from animals and plants — “we see plenty of ads on TV, but we have no evidence that any of these things are preventive,” said Dr. Steven DeKosky, a neurologist and deputy director of the McKnight Brain Institute at the University of Florida.

Dr. DeKosky led a federally supported study of Ginkgo biloba extract, for instance, following more than 3,000 people for seven years to see if it reduced dementia. It didn’t.

Some of the steps that may help according to article:

• Increased physical activity;

• Blood pressure management for people with hypertension, particularly in midlife;

• And cognitive training.