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Posted on Aug 30, 2006, 7 a.m.
By Bill Freeman
Diseases such as Alzheimer's and Parkinson's are marked by the slow and debilitating death of certain types of nerve cells in the brain. But new studies suggest that drugs similar to those already used to treat Parkinson's and other disorders could actually spur growth of new neurons, improving symptoms in animal models.
Diseases such as Alzheimer's and Parkinson's are marked by the slow and debilitating death of certain types of nerve cells in the brain. But new studies suggest that drugs similar to those already used to treat Parkinson's and other disorders could actually spur growth of new neurons, improving symptoms in animal models. Scientists hope that finding compounds that can enhance the brain's natural ability to grow new cells will provide a more effective treatment for neurodegenerative diseases and depression.
Drugs that trigger the birth of neurons could provide the next generation of treatments for neurodegenerative disease, as well as depression.
While the adult brain was once thought to be a mostly static structure, scientists have discovered in recent years that some parts of the brain -- most notably, the hippocampus, an area involved in learning and memory, and the subventricular zone, which lines one of the brain's fluid-filled cavities -- continually produce neurons, especially after injury. "We know new cells are made and go to the site of new injury, whether it's stroke or Parkinson's or Alzheimer's," says David Greenberg, a neuroscientist at the Buck Institute for Age Research in Novato, CA. "One strategy to treat neurodegeneration is to boost this response."
Recent studies have shown that many types of drugs -- antidepressants, cholesterol-lowering drugs, even Viagra -- spur growth of new neurons in the brain, a process called neurogenesis. While it's unclear exactly what role neurogenesis plays in the compounds' effectiveness, scientists can use these compounds to figure out how certain drugs trigger neurogenesis and then try to find or design compounds that boost new cell growth even more effectively in the specific parts of the brain damaged in a particular disease.
In Parkinson's disease, patients lose neurons that produce dopamine, an important signaling molecule in the brain. The disease is currently treated with drugs that replace or mimic dopamine, stimulating dopamine receptors on brain cells. While these drugs can alleviate some of the movement disorders that plague Parkinson's patients, they tend to lose their effectiveness over time.
In a study released last week in The Journal of Neuroscience, scientists found that a drug similar to those used to treat Parkinson's disease can spur growth of new neurons in the brain area damaged in the disease. Scientists found that treated animals had twice the number of proliferating neurons as control animals, and that many of the newly generated cells appeared to develop into dopamine neurons. In addition, the animals showed an 80 percent improvement in their motor ability. "The effects were really quite profound," says Christopher Eckman, a neuroscientist at the Mayo Clinic College of Medicine in Jacksonville, FL who led the study.
