The study examined the brains of 12 deceased men who had Parkinson's disease and compared them to the brains of 174 men who were of similar ages when they died and did not have Parkinson's disease. The researchers counted the number of neurons, or brain cells, in a section of the substantia nigra area of the brain. Parkinson's disease is caused by the gradual loss of cells in the substantia nigra. The average number of cells was significantly lower in the men with Parkinson's than in the other men. Furthermore, the longer the duration of Parkinson's disease, the lower the neuron count.
At the time of diagnosis, it was estimated that the men with Parkinson's disease had, on average, 40 percent fewer neurons than those without Parkinson's disease. With further analysis, the researchers estimated that the loss of neurons starts about 13 years before the diagnosis is made.
"If people destined to develop Parkinson's disease could be identified during this pre-clinical window, then theoretically it should be possible to intervene with some treatment to prevent the symptoms of Parkinson's disease from developing fully," said study author and neurologist G. Webster Ross, MD, of the Honolulu Department of Veterans Affairs in Honolulu, Hawaii. "We need to continue to look hard for biomarkers of Parkinson's disease that would help identify people with the disease before they develop the symptoms."
The study was supported by the National Institutes of Health, the National Institute of Neurological Disorders and Stroke, the National Institute on Aging, the Department of Veterans Affairs and the U.S. Department of the Army.
The American Academy of Neurology, an association of more than 18,000 neurologists and neuroscience professionals, is dedicated to improving patient care through education and research. A neurologist is a doctor with specialized training in diagnosing, treating and managing disorders of the brain and nervous system such as stroke, Alzheimer's disease, epilepsy, Parkinson's disease, autism and multiple sclerosis.
For more information about the American Academy of Neurology, visit its website at www.aan.com/press/.
Editor's Notes: Dr. Ross will present this research during a scientific session at the 56th Annual Meeting at 4:30 p.m. PT (7:30 p.m. ET) on Tuesday, April 27, in Room 305 of the Moscone Convention Center.