Smoking is bad for the brain

If your lungs, heart, pocket book, skin, teeth, etc were not enough, there is now another reason to quit smoking!

Smoking has been shown to be bad for your brain!BBC NEWS Health
Smoking 'is bad for your brain':

Researchers from the Universities of Aberdeen and Edinburgh looked at how the cognitive abilities of smokers and non-smokers changed over time. They found smokers performed significantly worse in five separate tests. The research, part of the Scottish Mental Health Survey, is published in New Scientist magazine.
http://news.bbc.co.uk/1/hi/health/4078841.stm

And yes they controlled for the "chicken or the egg" problem!