The findings suggest that both genetic and environmental factors may influence the development of Parkinson's, a progressive neurodegenerative disease marked by trembling of the arms and legs, stiffness and rigidity of the muscles and slowness of movement.
Previous studies have suggested that smokers and coffee drinkers have a lower risk of developing Parkinson's disease. However, this is the first study to look specifically at cigarette smoking and caffeine consumption within families affected by the disease, the researchers said.