A recently published, rather provocative study has suggested
Alzheimer’s disease may be caused in part by excessive
consumption of refined carbohydrates. Refined carbohydrates are
the starches and sugars you find in most processed foods that you
eat every day.

Refined carbohydrates may lead to Alzheimer’s in two ways. First,
they appear to alter fat metabolism within the central nervous
system, which inhibits some functions of cell membranes. Second,
they stimulate prolonged and excessive insulin and insulin-like
growth factor signaling, which increases brain cell damage.

Reducing refined dietary carbohydrates, and increasing essential fatty acids may help prevent Alzheimer’s disease.

Source: High Carbohydrate Diets and Alzheimer’s
Disease,” Henderson ST, Med Hypotheses, 2004;62:689-700