OK Ignoring for a moment All the (many) negative health problems smoking causes... There is proof that nicotine does induce a form of relaxation and calmness in people. This is one of the reasons that many people who have mental troubles also smoke. It's a form of self medicating.

I don't know if they increase your risk, but I am certain that smoking cigarettes can complicate problems already present in diseases like Alzheimer's and dementia.

http://en.wikipedia.org/wiki/Nicotine "With regard to neurological diseases, a large body of evidence suggests that the risks of Parkinson's disease or Alzheimer's disease might be twice as high for non-smokers than for smokers.[24] Many such papers regarding Alzheimer's disease[25] and Parkinson's Disease[26] have been published. Recent studies have indicated that nicotine can be used to help adults suffering from Autosomal dominant nocturnal frontal lobe epilepsy. The same areas that cause seizures in that form of epilepsy are also responsible for processing nicotine in the brain.[27] Nicotine and its metabolites are being researched for the treatment of a number of disorders, including ADHD and Parkinson's Disease. [28]" Interesting. The article you cite has some interesting points also and I do believe there is a link between mental illness and cigarettes/nicotine. However, I do not believe it *increases* the risk. You ask a question the right way you can get a study which says almost anything - that I do believe. There is so much we still have to learn about the brain and tracing the effects of things which alter the chemistry, from drugs such as nicotine to sex. I signed up for that study but was rejected. (haha)

Cigarettes DO NOT cause any mental health problems whatsoever, only physical problems.