Back to Menu

Prevention of Alzheimer's - Still a muddle
(April 2005)

At a recent International Conference on Alzheimer's and Related Diseases, there were many papers on prevention of Alzheimer's, the suggested approaches including:

- losing weight and avoiding obesity which is said to increase risk by threefold

- controlling blood pressure and cholesterol levels

- eating healthy foods

- keeping mentally active

- including plenty of green leafy vegetables and cruciferous vegetables (cauliflower, brussel sprouts, cabbage, broccoli) in your diet

- keeping physically active

- getting plenty of antioxidants in your diet or through supplements

- having good blood levels of high-density lipoprotein cholesterol (HDL, good cholesterol)

Not surprisingly, an increasing number of studies on dietary prevention of Alzheimer's have appeared in the medical and lay literatures. High caloric intake, overweight, consumption of saturated fats have all been implicated as increasing risk, whereas a high intake of polyunsaturated fats, fish (and omega-3 fatty acids) and antioxidants have been said to be protective.

The problem is that there is no consistency among the various studies and, even in positive studies, there are inconsistencies. For example, in one study on overweight as a risk factor, the overweight results applied to women, not men. In another study implicating fat and high caloric intake, the results applied only to the one-quarter of the study group with a specific genetic variation that is associated with higher Alzheimer's risk. One study shows that eating fish once a week is protective, another that there is no protection from eating fish. One study says vitamin E is protective, but only from foods, not supplements; another finds no protection from any antioxidant (vitamin C, vitamin E, Beta carotene).

A recent study suggests a good intake of niacin (vitamin B3) in the diet can help prevent mental decline with aging or Alzheimer's. The niacin study was carried out on 818 men and women, 181 of whom developed Alzheimer's over a four-year period. The 815 were divided into five groups (quintiles) according to niacin intake. Foods rich in niacin include:  meats, poultry, legumes, fish, enriched cereals, and grains. Compared to the lowest niacin intake group, the higher intake groups had a 40 to 70 percent reduced risk of developing Alzheimer's. A puzzling finding was that the reduced risk was found in the second lowest intake of niacin and the extent of protection increased only a very small amount as niacin content of the diet increased. It was not clear whether niacin-containing supplements were effective in reducing Alzheimer Disease risk.  This is an interesting, but clearly preliminary, report.

Thus far, the most intriguing relationship between diet, mental functioning, and development of dementia is for fish that contain large amounts of unsaturated omega-3 fatty acids. Mental decline with aging appeared greater with low intake of these fish, the risk of developing Alzheimer Disease may be reduced by good intake of fish high in omega-3 fatty acids, and the brains of patients with Alzheimer Disease appear to have lower amounts of certain omega-3 fatty acids. All this may be intriguing, but there are inconsistencies among the results of various studies and, thus far, no relation is proved between omega-3 fatty acid intake and/or dietary fish intake and either mental functioning or prevention of Alzheimer's.

We are going to hear a lot about vitamins, antioxidants, and other dietary and lifestyle factors as Alzheimer's preventives. However, as of this writing, the bottom line remains:

There is no adequately documented dietary prescription, dietary supplement, lifestyle behavior, or medication that can predictably delay the occurrence of or prevent Alzheimer Disease .

Scientists are making great progress in understanding Alzheimer's, and that understanding will eventually lead to both effective treatment and prevention - and we may find some fully-documented dietary, lifestyle, or other preventive - but not yet.

Morris, M., et al. Dietary niacin and the risk of incident Alzheimer's disease. Journal of Neurology, Neurosurgery, Psychiatry. Vol 75 (July) Pgs 1093-1099. 2004.