People who drink lots of coffee may be less likely to develop Parkinson's disease (PD), according to a study published today in the journal Neurology. But before you race off to refill your mug, consider this: the coffee itself may not be conferring resistance.

Neurologist Walter Rocca of the Mayo Clinic and his colleagues studied 196 people with the disease and 196 without it. Intriguingly, whereas 83 percent of Parkinson's patients were regular coffee drinkers, 92 percent of the control group made java part of their routine. Similarly, 21 percent of those with the disease drank four or more cups per day; 37 percent did so in the control group. And among those participants with PD, those who drank coffee developed the disease eight years later than those who did not. Furthermore, the researchers found that alcoholics and people who used chewing tobacco and snuff were also less likely to develop PD. (The team also tested the purported inverse association between cigarette smoking and Parkinson's and failed to detect a correlation.)

Taking those results into consideration, the team suspects that the coffee itself is not protecting against Parkinson's (although they have not ruled out that possibility). Rather, they suggest, it may be that people who suffer from PD manifest a certain personality early in life that leads them to avoid using unhealthy or addictive substances such as tobacco, alcohol and coffee. Indeed, individuals who later develop PD are sometimes described as moralistic, conscientious, cautious and orderly, the team reports. "These personality traits can be combined into the concept of 'reduced novelty seeking'," they write. "Novelty-seeking behavior has been linked to substance abuse and addiction and in turn has been found to be less common in PD cases than in control subjects."