Correlation and Causation are not the same thing........as any scientist or Doctor would tell you. Very interested in the study as I have Ehlers Danlos Syndrome and have consistent inflammation due to joint issues and constant dislocations. I have used nicotine and caffeine as well as other ways to increase energy just to live before I was diagnosed. This now makes a lot of sense as if I was depleted in Dopamine, that is why I was using and addicted to things that increased it in a reward system.