Does the combination of diet, exercising, sleeping and stress reduction help in the prevention of Alzheimer's disease?

Question

Rudy Tanzi, Ph.D director of the Alzheimer’s Genome Project and a leading researcher in the field at Massachusetts General Hospital and Harvard Medical School states that eating fruits and vegetables through diet, exercising, sleeping and stress reduction helps in the prevention of Alzheimer's.

Q: Aside from choosing the right parents, what can somebody do to prevent Alzheimer’s – or try to help prevent Alzheimer’s?

A: The four big categories are diet, exercise, sleep and stress reduction. I wrote about this in detail in my last book, “Super Genes” – six chapters, more than you wanted to know about how to adapt your diet to minimize inflammation and plaques. Meaning Mediterranean diet, probiotics – take care of your gut bacteria. Source: Top Alzheimer's researcher explains how you can help protect your brain

Is there research evidence to back up the above claim that people will be in less risk to be affected by Alzheimer's if they perform those four activities?

Answer 1

There is researched support for all of the claims except sleep where there is only a correlation

It seems so for diet with the statement:

Our findings in this well-characterised Australian cohort indicate that adherence to a healthy diet is important to reduce risk for cognitive decline

Also for exercise, with the statement:

Lower plasma Aβ(1-42/1-40) and brain amyloid was observed in those reporting higher levels of physical activity, consistent with the hypothesis that physical activity may be involved in the modulation of pathogenic changes associated with AD.

There also appears to be a link between anxiety and AD, however I haven't found one specifically mentioning stress. This article states:

findings suggest that interventions to mitigate anxiety symptoms may help delay memory decline in otherwise healthy older adults with elevated beta-amyloid.

However I found no papers directly relating to sleep, only this NHS post disputing the daily mail's claim that there was such a link. The NHS article says:

A new US study did find a link between poor sleep quality and higher levels of clumps of abnormal proteins in the brain (known as beta-amyloid plaques), but no cause and effect relationship between sleep quality and Alzheimer’s disease was proven.