— Curing Alzheimer’s disease may be impossible and the best hope to control the disease may require beginning treatments as much as 20 years before the onset of symptoms. It could take decades to find effective therapies for the brain-wasting disease.
That is the view of Dr. Sam Gandy, a highly respected Alzheimer's expert at Mount Sinai Medical Center in New York. Writing a perspective article titled “Prevention is Better than Cure” in this week’s issue of the journal Nature, Gandy offers an argument that will likely dominate much of the discussion next week when 4,000 researchers gather in Paris for the Alzheimer’s Association’s Annual International Conference.
Gandy notes it has been more than a century since the German psychiatrist Alois Alzheimer described the condition that bears his name. Dr. Alzheimer discovered the disease in a 51-year-old woman called Auguste D. After her death, Alzheimer noticed her brain was speckled with plaques of a protein now known as amyloid-beta peptide.
In recent decades, on the basis of sound evidence, many scientists have concluded that amyloid plaques play a key role in causing the devastation of Alzheimer’s disease. The pharmaceutical industry has produced drugs and vaccines designed to clear the plaques from the brain. The problem is, in a few large studies the plaque goes away, but the symptoms of the disease continue to worsen.
One camp among Alzheimer’s researchers believes this shows that amyloid is simply not the cause. But the majority of researchers, like Gandy, believe that once the plaque appears the damage to the brain is too great to undo and the only hope is to prevent it. Recent studies using brain scans, spinal fluid and blood samples have been searching for signs that appear before the psychological tests reveal the onset of dementia. Much of this work is centered on the handful of families where some members carry a dominant gene variation that causes them to get Alzheimer’s in their 30s, 40s or 50s, but that type of screening is expected to become more common.
It is increasingly apparent from these studies that many of these changes occur as much as 20 years before the symptoms of the disease. Alzheimer's can progress at different rates but typically develops through different stages, beginning with mild cognitive impairment — forgetting familiar words or losing common objects — to difficulty performing tasks to severe dementia and the inability to carry on a conversation or control movements.
Scientists believe it might be necessary to administer amyloid-lowering drugs early in the course of the disease — long before it is anything that could be called a disease. It also seems likely that it will take years to prove whether any drugs work.
However, getting started with any course of treatment quickly is vital. By 2050, it's estimated that as many as 16 million Americans will have the disease. Most people survive about four to eight years after diagnosis, but some can live as long as 20 years with the disease, according to the Alzheimer's Association.
Gandy writes that “we should not be discouraged by the prospect of another decade or two of work” to know whether controlling amyloid is the key to controlling Alzheimer’s disease. “Prophylactic intervention,” he writes, “is now the best hope.”