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Medical Fact of the Day – How Can Smoking and Coffee Be Good for You?

Smoking is probably the single largest preventable cause of deaths worldwide, increasing the chance of lung cancer, emphysema, atherosclerosis, and hypertension. But how can it be good for you?

In several studies, patients who smoked or consumed caffeine daily were significantly less likely to have Parkinson's Disease. Furthermore, increasing the smoking or caffeine dose further decreased the risk.

Of course, this is not to say that one should smoke purely to avoid Parkinson's. But it does raise the question of the mechanism of this effect. Parkinson's is a deficiency in dopamine-producing neurons in the brain. Dopamine is a neurotransmitter that is essential in maintaining reward (which is mainly why smokers become addicted) and muscle movements. Take away dopamine, and you no longer have smooth muscle movements, showing Parkinson's symptoms.

So might it be that overusing the reward circuit has a protective effect on dopamine-producing cells? Or are there other chemicals in smoking that prevent dopamine-producing cells from dying? To find this out, a scientist might investigate whether any other addiction showed decreased risk of Parkinson's. Clarifying interesting mechanisms like this one can lead to new treatments.

Bonus: I came across this site claiming many more benefits of smoking, some with more dubious data. The organization behind that site wishes to rid government intervention in "personal lifestyle choices" of diet and habits. In the case of smoking, intervention was clearly needed to dampen the effects of secondhand smoke. But it's often  useful to try to understand opposite viewpoints and critically evaluate evidence.

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