It's been nearly a decade since the FDA approved a new treatment for Alzheimer's disease patients. Like much of disease research, many early studies show some promise -- but researchers say finding advances in prevention and treatment for Alzheimer's has been just as slow as the progression of the disease itself.
"It's problematic," said Dr. Gary Small, director of the Center on Aging at the University of California-Los Angeles. "We have no disease-modifying treatments."
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The FDA has only approved two types of medication to improve cognitive symptoms of Alzheimer's disease such as memory loss, according to the Alzheimer's Association. But there is no treatment that stops or reverses its progression.
The problem could lay in not enough study participants and not enough funding for clinical trials, according to the Alzheimer's Association.
About $6 billion of funding is funneled to cancer research, and $4 billion is spent on heart disease research. Only $500 million has been allocated to Alzheimer's research, according to the Alzheimer's Association.
According to some experts, the problem lies, in part, with researchers not able to identify which mechanisms in the brain to target when studying potential treatments.
"When we examine the brains of [Alzheimer's disease] patients, there are many changes and we are not sure which changes are the earliest and most important," said Dr. Richard Lipton, neurologist at Montefiore Medical Center and professor of neurology at Albert Einstein College of Medicine.
Most research has banked on targeting beta-amyloid plaques, which build up in the brain as the disease progresses.
"I think there's been an overemphasis [in research] on amyloid but we're not seeing any results on this work," said Small.
In fact, Small said tau protein tangles, which also build up in the brain of Alzheimer's patients, also may serve as an important key to treatment research. So, too, is the possibility that inflammation in the brain can trigger the disease.
"It's complicated," said Small. "And to do these studies and really know, we have to be focused on only one mechanism at a time."
But research is headed in the right direction, said Dr. Paul Aisen, director of the Alzheimer's Disease Cooperative Study at University of California-San Diego School of Medicine.
Earlier detection of the disease before physical symptoms appear is a vital step to treatment, said Aisen.
"We're not quite there yet, but we have it in sight," he said. "There's a lot in the pipeline that make the outlook more optimistic today than in recent years."
Many early trials show promise -- including research on nerve growth factor, a protein that works to preserve and restore nerve cells.
"We are working on a possible new class of drugs for Alzheimer's disease that can prevent the death of cells in the brain and stimulate the function of the remaining cells," said Dr. Mark Tuszynki, a professor of neurosciences, and director of the Center for Neural Repair, whose research looks at nerve growth factor to manipulate cells. "The death of the cells is largely prevented."
So far, nerve growth factor has been effective in animal studies. If effective in the current clinical trial, it may still be at least five years before it is approved as a potential disease-modifying treatment.