New research suggests that the genetic makeup of people with Parkinson’s disease may determine how they respond to caffeine, which is generally associated with a lower risk of the disease. The findings, reported today at the World Parkinson Congress (WPC) in Glasgow, Scotland, come from one of the first genome wide association studies (GWAS) to look at genetic and environmental interactions.
The investigators scanned the complete genetic code (genome) of 4,000 people, about half of whom had Parkinson’s disease, for nearly 1 million markers. They then collected data on the amount of caffeinated coffee the subjects drank over their lifetimes.
Previous studies have shown that caffeinated coffee and tea may decrease the risk of developing Parkinson’s. Preliminary findings from this new study suggest that subjects who carry a version of the gene GRIN2A benefited the most from coffee.
The new findings may help researchers identify patients who are likely to respond to drugs that target the same physiological pathways as caffeine. Such drugs are currently being investigated as new treatments for Parkinson’s.
“This work shows the potential of using genetic and epidemiological approaches to identify new risk factors for Parkinson’s disease,” said Dr. Margaret Sutherland, a program director at the National Institute of Neurological Disorders and Stroke (NINDS). “The next challenge will be to validate that the coffee and GRIN2A association can be replicated in a larger group of patients.”
Dr. Kieran Breen, director of Research and Development at Parkinson’s UK, said: “We are excited by these initial findings. However, more work needs to be done to expand and better understand this study so that in the future we may be better able to target drugs to specific people with Parkinson’s. But for today, patients should not change their caffeine consumption.”
Researchers are hopeful that new drugs, without caffeine’s stimulant and diuretic effects, will prove helpful to patients. In clinical trials, however, such drugs have failed to meet the threshold for effectiveness and regulatory approval.
“The new results suggest the possibility of screening patients for their genetic makeup to determine if they are likely to benefit from drugs that target the brain cells affected by caffeine. Such screening could be done at the outset of clinical trials, and could also become part of routine practice,” said the lead researcher Dr. Haydeh Payami, an investigator at the New York State Department of Health Wadsworth Center in Albany. Her work was funded in part by NINDS, a part of the U.S. National Institutes of Health, and by the Michael J. Fox Foundation for Parkinson’s Research Edmond J. Safra Global Genetics Consortia initiative. (For more research by Dr. Payami, see Researchers Find Connection between Parkinson’s Disease and Immune System-Related Gene.)
Parkinson’s disease attacks parts of the brain that are needed to control movement. Common symptoms include involuntary shaking, slow movement, stiff muscles and impaired balance, all which worsen as the disease progresses. A drug called L-dopa can control symptoms, but causes troubling side effects and does not slow progression of the disease.