Not trying to get all preachy on y'all, but here's yet another reason not to smoke: it affects your noggin. UCLA researchers compared brain function in teen smokers and non-smokers, particularly the prefrontal cortex (the part of the brain that guides decision-making). Here's the interesting part: as a teen, along with other parts of your body, your prefrontal cortex isn't fully developed yet. And the study's results showed that the more addicted a teen was to nicotine, the less active the prefrontal cortex was, meaning that smoking could affect brain development and stunt its growth.
Edythe London, the study's lead author, has said, "as the prefrontal cortex continues to develop during the critical period of adolescence, smoking may influence the trajectory of brain development, affecting the function of the prefrontal cortex. In turn, if the prefrontal cortex is negatively impacted, a teen may be more likely to start smoking and to keep smoking -- instead of making the decision that would favor a healthier life."
So now we know that not only does smoking cause yellow teeth, bad breath, and cancer, but also making you potentially dumber. Yeah, no thanks. We heart our brains too much.