High-Fat Diet in Early Adulthood May Be Associated With Increased Risk of Alzheimer's

Alzheimer's Association
Wednesday, 12 July 2000

A high-fat diet during early and mid-adulthood may be associated with an increased risk of developing Alzheimer's disease, especially in people with a marker called the ApoE-e 4 allele, say researchers at the Case Western Reserve University School of Medicine and University Hospitals of Cleveland.

The scientists reported their study results today at World Alzheimer Congress 2000.

In a retrospective analysis that examined foods eaten by 304 men and women (72 with Alzheimer's disease and 232 healthy people), lead researcher Grace Petot and her colleagues found that people with the ApoE-e 4 allele who also consumed the highest fat diets had a seven-fold higher risk of developing Alzheimer's disease than people with the marker who ate lower fat diets. The participants were, on average, in their 70s when the study began in 1991.

ApoE stands for apolipoprotein E, a key protein involved in the transport and disposal of cholesterol. It is expressed in three forms, or alleles: e 2, e 3 and e 4. Earlier research has indicated that the e 4 form is related to the development of Alzheimer's disease.

"We know that peoples' diets change with time; particularly, the intake of total fat and saturated fat seems to increase when people age from 40 to 6o years," said Petot, assistant professor emeritus of nutrition at the Case Western Reserve University School of Medicine. "In our study, we found that people aged 40 to 59 with the ApoE-e 4 allele who had diets in which more than 40 percent of the calories came from fat had a 29-fold increased risk of developing Alzheimer's disease compared with people who ate high-fat diets and no e 4 allelle. In contrast, people with the marker whose consumption of fat was less than 35 percent of their calories had a four-fold increased risk of developing the disease compared with those with no e 4 and lower fat diets."

ApoE-e 4 carriers aged 60 and over who consumed a similar high-fat diet had a 12-fold higher risk of developing Alzheimer's than those who ate a high-fat diet and did not have the e 4. In people aged 20-39, the combination of ApoE-e 4 and a diet with more than 40 percent of calories from fat raised the risk of Alzheimer's by almost 23 times compared with those with high fat diets no ApoE-e 4.

This seems to tie-in with the theory that mechanisms that influence the development of Alzheimer's disease occur early in life, said Petot.

Bill Thies, Ph.D., vice president of medial and scientific affairs for the Alzheimer's Association (U.S.A.) agrees. "It has long been hypothesized that early life experiences may affect the development of Alzheimer's disease," says Thies. "Proper nutrition and a healthy diet are essential for maintaining overall good health and can be beneficial to both people with Alzheimer's disease and caregivers."

The control subjects also consumed more dietary antioxidants, which may have exerted a protective effect, she added. Fat may be subject to a process called oxidation, which results in the formation of damaging chemicals called free oxygen radicals that can cause tissue injury. Antioxidant nutrients, as well as other chemicals called flavonoids and carotenoids, can act as defenses against these molecular flamethrowers.

"What this study tells us is that we need to look a lot harder at peoples' habits, particularly since we saw an association between fat consumption at a relatively early age and the subsequent development of Alzheimer's disease," Petot said. "The association between genes and the Alzheimer's risk associated with diet suggests that genetic testing may be valuable for helping people make choices about lifestyle," said Friedland, associate professor in the department of neurology at the Case Western Reserve University School of Medicine.

For more information, or to contact Alzheimer's Association, see their website at: www.alz.org