Alzheimer’s Researcher Says He Has a Clue to Delay Onset

The discoverer of a genetic trait linked to Alzheimer’s disease says he has figured out how it causes the disease: by weakening the “plumbing” that carries nutrients to brain cells and flushes out the waste.

The new understanding offers numerous possibilities for the development of drugs that might not “cure” the disease but could delay its onset for 20 years, meaning most people would not live long enough to get it, said Dr. Allen Roses, chairman of the neurology department at Duke University Medical Center.

Speaking Monday at a meeting sponsored by the Council for the Advancement of Science Writing, Roses also reported that people with the Alzheimer’s gene are more likely than others to die after a head injury, because of the weakened condition of their nerve cells.

The gene produces a substance called apolipoprotein E4, or apo E4, which shuttles cholesterol through the bloodstream. Roses’ belief that apo E4 is critical in Alzheimer’s puts him at odds with some other leading authorities.

“No one disputes that E4 is important; [but] E4 is a risk factor, not the cause,” said Dr. Dennis Selkoe, a neurologist at Harvard Medical School.

Selkoe believes that E4 somehow changes the form of a substance called amyloid in the brain. The brains of Alzheimer’s victims are laced with amyloid plaques, or deposits, that Selkoe and others believe are the central feature of Alzheimer’s disease.

Roses said he believes that amyloid is an incidental consequence of damage produced by apo E4, and that amyloid is not central to the disease itself. About 2% of Americans have two copies of the apo E4 gene, giving them a 50% chance of getting Alzheimer’s before age 70.

An estimated 4 million Americans suffer from Alzheimer’s disease, and 100,000 die of it every year.