Genetics, coffee consumption, and Parkinson’s disease
Marta Gwinn, MD, MPH
Office of Public Health Genomics
Centers for Disease Control and Prevention
Hamza TH, et al. Genome-Wide Gene-Environment Study Identifies Glutamate Receptor Gene GRIN2A as a Parkinson’s Disease Modifier Gene via Interaction with Coffee. PLoS Genet 2011;7(8): e1002237.
Parkinson’s disease (PD) is the second most common neurodegenerative disease after Alzheimer’s disease. Population prevalence of PD increases from about 1% at age 60 to 4% by age 80. Early symptoms of PD include tremor, rigidity, and difficulty walking; cognitive decline is common at later stages. The underlying pathology of PD is selective death of dopamine-generating cells in the substantia nigra, a part of the brain involved in movement, reward, and addiction. Treatment of PD with levodopa temporarily controls motor symptoms but does not slow disease progression. Like other common diseases, PD is thought to arise from complex interactions between genetic and environmental factors, which remain mostly unknown.
Many epidemiologic studies have found that PD is less common in people who drink coffee, as well as in those who smoke cigarettes. These findings are remarkably consistent and they have survived an exhaustive search for non-causal explanations. No one would suggest taking up smoking (or even coffee drinking) to prevent PD; however, understanding their “protective effects” could shed light on its molecular pathology. Such insights could suggest new treatments that not only treat symptoms but can slow or halt disease progression.