Anti-psychotic medications are commonly used in treating Alzheimer's patients.
"It's what your doctor would really see," said Dr. Rachelle S. Doody, lead author of the Dimebon study and director of the Alzheimer's Disease and Memory Disorders Center Baylor College of Medicine in Houston.
"For us to be able to see not only a positive signal, but a signal on all five measures is very reassuring and hopeful," Doody said. Dimebon also improved patients' scores by an average of two points on a 70-point scale of mental functioning.
When compared to the patients on placebo who were declining, patients receiving Dimebon scored an average of seven points higher on the scale. Those seven points account for a real-world equivalent of slowing memory loss by one year, according to the Aging Research Center.
But doctors, including Doody, don't know exactly how Dimebon works, which leaves questions about how the drug might interact with current Alzheimer's medications and even measure up to them.
"The effect was strong but absent a direct head-to-head comparison it might be a bit too much to say that Dimebon blows the competition out of the water," said Karl Herrup, chair of the Cell Biology and Neuroscience Department at Rutgers University in Piscataway, N.J.
"The question would be whether it has an additive effect if it were administered along with current medicines," Herrup said. "Since it may be acting through the same pathways, there may be no added benefit."
Dr. Doody's team originally thought Dimebon worked in the same way as the two main types of Alzheimer's drugs &$151; cholinesterase inhibitors and NMDA-receptor antagonists. But now Doody suspects Dimebon might functions differently.
"This drug does both of those functions, but weakly," Doody said. "We think that those two drug actions are really not important to why it was successful."
Instead, Doody believe Dimebon's action centers around mitochondria — the so-called power plants of cells — keeping brain cells functioning, maintaining communication between brain cells and potentially protecting them from death. Yet all of that still only treats the symptoms of Alzheimer's.
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