As proponents of stem cell research rally behind hopes of curing Alzheimer's disease, the answers likely lie elsewhere.
"There are many other avenues that are being pursued that are more likely to be valuable than stem cell research," said Dr. Rachelle Doody, a professor of neurology and director of the Alzheimer's Disease Center at Baylor College of Medicine in Houston . "There may be something that comes out of stem cell research that's helpful in Alzheimer's later, but it's not the primary focus."
Stem cells can potentially reproduce a single kind of tissue in the body, but because Alzheimer's disease affects multiple parts of the brain, stem cell research is unlikely to uncover a cure in the immediate future, she said.
"In Alzheimer's, you couldn't hope to replace all the dying neurons, all the dying support cells, all of the specific biochemical subtypes of cells that are involved," Doody said.
Although stem cells appear to have limited applications in cases of Alzheimer's disease, "nobody likes to see a whole avenue of research that is closed," Doody said. Because stem cells can form many kinds of cells, advocates of stem cell research cite the potential benefits of regenerating cells in patients who suffer from conditions like Parkinson's disease, diabetes, and muscular dystrophy.
For now, researchers' best hope lies in medication, according to Doody, although progress has been limited. While an estimated 2,000 patents pertaining to treatments for Alzheimer's disease currently exist, only five drugs have ever been approved by the Food and Drug Administration for clinical use, and just four of those are regularly prescribed.
Some studies have shown that combining current drugs may be an effective treatment for Alzheimer's, but no therapy has been able to halt progression of the disease permanently. Doody estimates that approximately 80 percent of her patients respond favorably to current medications, but actual improvements related to these drugs are invariably short-lived, usually lasting less than a year. Those who continue to take drugs beyond a year can still benefit by maintaining more cognitive and functional abilities compared to untreated patients for many years.
Major hurdles in medicinal studies on preventing the disease include a relative lack of funding for research and the need for extremely long-term analysis, she said. The gradual, degenerative nature of the disorder requires that at least a decade of research be conducted before any significant conclusions can be drawn.
Doody says that while no single therapeutic measure can alleviate the causes or symptoms of Alzheimer's, a combination of methods remains the best option for now.
"I don't believe that Alzheimer's is the kind of process that you find the one cure," she said.
She adds that no matter how many scientific discoveries come to light, some patients will invariably fail to respond well enough to any kind of medication, spurring further research in areas that may one day include stem cells.