Genes alone don't foretell Alzheimer's disease risk

Researchers looking for genes that contribute to late-onset Alzheimer's disease have found little to help them predict who is at higher risk of developing the condition.

The study, released Tuesday in the Journal of the American Medical Assn., was a genome-wide association study of 35,000 people. The researchers identified several genes linked to the disease but found that knowledge of these genes and their location on chromosomes did not improve their ability to predict who would develop Alzheimer's disease. The knowledge of genes related to the disease could, however, help with research into what causes it, the researchers concluded.

Identifying a number of genes involved in a disease that only have a small effect may not be very helpful, said Nancy L. Pedersen, of the Karolinska Institute in Sweden, in a commentary accompanying the study. She notes that Alzheimer's disease is highly hereditary but that only one known gene -- the APOE gene -- significantly increases the risk. The disease likely is the result of a number of genes, their combinations and, possibly, a combination of those genes and the environment.

The study, Pedersen writes, "is a fresh reminder that family history is very important, even for late-onset disease that was once thought to be sporadic." One's age, sex, family history and APOE status remain the most important factors for predicting risk of the disease.

-- Shari Roan

Photo: Steve Osman  /  Los Angeles Times

Comments

[Carlyn]

Interesting study!

[Karen Krahl, D.C.]

My mother died of Alzheimer's disease, and I have read a great deal about it. It doesn't surprise me that the search for a genetic link hasn't come up with a simple answer. The Functional Medicine approach to preventing and reversing chronic illness, promotes taking a systems biology/multifactoral approach to diagnosing, and then treating with targeted nutrition, lifestyle changes, and when necessary medications. It takes into consideration genetic propensities, but it's what your genes are "bathed in ", that changes outcomes. Lifestyle effects have to do with toxic exposures, stress, exercise, injuries and infections, what you eat and what you inhale. In my mother's case; retrospectively I can point to a number of things that contributed. There was no family history of Alzheimer's or dementia in her case. However; she grew up in a very polluted Pittsburgh, was depressed most of her adult life, lived with undiagnosed celiac disease, which no doubt caused numerous micronutrient deficiencies that have been linked to long latency disease, she smoked at least a pack of cigarettes a day her whole life until she could no longer remember how to light a match, she had untreated high cholesterol that was not discovered until she began to have a heart attack during a stress EKG. She underwent triple by-pass surgery 3 times in one night! Although she survived, being under for that long has been linked to dementia. It was within 6 or 7 years after this she began to have cognitive decline. She was a very poor "methylator, and acetylator." These are detox pathways in the cytochrome P-450 system in the liver. There is some connection between exposures to neurotoxins, and not being able to detoxify them that leads to nervous system damage. She always had side effects from medication, and it was more likely in her case that the anesthesia would have harmed her brain. She always cooked in aluminum, and drank from aluminum cans. It is likely because of her indoor lifestyle, she was vitamin D deficient her whole life. D lowers inflammatory load. Chronic poor circulation, and high levels of inflammation are associated with increased risk of AD. In Neurology Reviews, there was a recent article that pointed out the salutory effect of the Mediterranean diet, on brain health and cognition and specifically in the prevention of AD. My mother put butter on her pastry, fried and baked with butter or Crisco, and ate the Standard American Diet, of overcooked vegetables, iceberg lettuce, mayonnaise, red meat, potates, and canned fruit. In her case the effects were additive and calamitous. Advice? Stay active, sharp, eat low on the food chain, follow the Dr. Andrew Weil anti-inflammatory food pyramid, and Dr. Mark Hyman's the UltraMind Solution, and go outside...play in the sunshine. Drink from glass or stainless steel, or porcelain, avoid charred meats and deep fried foods, eat organic, and avoid high fructose corn syrup. Get your "oil" checked, i.e your D