Document type: Report

DOPAMINE.DOC Page 4 TALKING POINTS REGARDING STUDY IN NATURE | Much media attention has been given to the story about smoking, an enzyme called monoamine oxidase B (MAO B), and a neurotransmitter called dopamine. The press reports say the study claims that smokers have a lower concentration of the MAO-B enzyme in their brains. The study claims that since the MAO-B enzyme breaks down dopamine, having a lower level of this enzyme presumably has the effect of giving smokers an "addictive high" resulting from higher levels of dopamine. The study's authors claim that this could explain why smoking is “addictive.” There are important points which may not be clear to readers from these press reports. It is unreasonable and illogical to equate dopamine with “addiction.". Dopamine release is found in a wide array of situations and events. Animals studies have shown that dopamine is released as a result of both positive and negative circumstances -- including painful or stressful situations that would certainly not create reinforcing or "addictive" behavior. Dopamine release can be triggered by any important or emotional event -- whether it's pleasurable or painful stimulation. For example, hungry rats which are fed then release dopamine; and thirsty rats who get water release dopamine when they drink. But stressful or painful experiences -- such as an electric shock -- also stimulate the release of dopamine. If these animal studies reflect to some degree the human situation, then the same thing would hold true: dopamine release is stimulated by both pleasant and painful experiences -- whether it comes from seeing someone you're very happy to see, or dropping a heavy object on your foot. Based on media reports about the dopamine study, it's impossible to tell whether the study reported was controlled for confounding variables -- such as diet, how much someone smokes, or how recently they smoked before the study. These variables would be critical in determining what role, if any, smoking might play in the reduction of dopamine. Aside from smoking, many other aspects of the lifestyles of smokers and non-smokers tend to be very different -- which introduces confounding variables into studies of differences between smokers and non-smokers. The study's authors compare the effects of smoking to the effect of drugs such as heroin and cocaine, Although there are issues regarding the molecular affects of certain substances that we don't understand very well, it is obvious that there are clear behavioral differences between people who smoke and people who use drugs such as heroin and cocaine. Regardless of how you define addiction, cigarettes are clearly not in the same class as addictive, mind-altering drugs like heroine and cocaine. For example, smokers do not become intoxicated or suffer from black-outs. The fact that behaviors like smoking or drinking coffee may be difficult for some people to stop does not mean they are addictive. Any behavior you enjoy can be difficult to change -- depending on the individual and the situation. , Note: If someone wanted a reference to a published scientific article on this subject, our Legal or R&D Department could provide a citation. CONFIDENTIAL & PRIVILEGED an BH sos ray ea ao ~~ © wn