Many persons with Schizophrenia smokes and many of them have become heavy user’s long time before getting sick. There is obviously something with smoking, first of all it is very hard to start smoking and you really have to be strong to start smoking because the instincts tell almost everyone to puke when they inhale the first times.

But it is also hard to stop smoking. And it will be almost impossible to predict al the actions of 10 thousand different substances in the pyrolysis cocktail. But something we do know.
* The rate of smoking in people with schizophrenia is at least two to three times that in the general population
* Patients who smoke, smoke at heavier rates than in the general population
* Most patients start smoking in their teens, before the illness begins

A possible explanation for the association between schizophrenia and smoking is that smoking acts as an etiological risk factor for schizophrenia. It may be that repeated activation by nicotine of the mesolimbic system over a long time precipitates the onset of schizophrenia in vulnerable individuals. Researchers found that the earlier the age of starting smoking, the earlier was the onset of psychotic illness in women (Kelly & McCreadie, 1999). Interestingly, nicotine acts like other drugs of addiction such as cocaine and amphetamine, activating the mesolimbic dopamine system (Pontieri et al, 1996) and this is probably an effect of the M.A.O inhibiting effects of tobacco.

On the other hand genetic and/or environmental factors might predispose individuals to develop both schizophrenia and nicotine addiction. Much work in the genetics of both schizophrenia but very little has been done to clarify the positive effects of nicotine on the immune-response in Schizophrenia. CD25 and CD69 increased the expression when exposed to plasma from persons with Schizophrenia, suggesting that enchanted Il-2 processing….

“These results suggest that cigarette smoking has selective effects on serum components that, in turn, lead to altered immune function in schizophrenia patients relative to healthy subjects. Further studies aimed at characterizing these components could result in a better understanding of the onset and aetiology of schizophrenia and potentially lead to novel therapeutic strategies”

The changes does not correlate with changes in nicotine or cotinine levels

The most intriguing finding of the current study was the observed increase in T-cell proliferation after exposure to serum from schizophrenic smokers.  We have demonstrated that this effect was not due to differences in nicotine metabolism as cotinine levels were not significantly different in the sera of schizophrenic and control smokers. We also excluded the possibility that the effect was due to alterations in the inflammatory response by showing that the concentrations of IL-10 and IFN-g in serum from schizophrenic and HC smokers were comparable.

References:

Differential effects on T-cell function following exposure to serum from schizophrenia smokers
M Herberth, DN Krzyszton. 2008

Cigarette smoking and schizophrenia
Advances in Psychiatric Treatment (2000) 6: 327-331, the Royal College of Psychiatrists
Ciara Kelly and Robin McCreadie

Schizophrenia, Monoamine Oxidase Activity, and Cigarette Smoking
Neuropsychopharmacology (1999) 20 392-394.10.1038.George M Simpson MD, Jean C Shih Ph.D, Kevin Chen MD, Calvin Flowers MD, Takachi Kumazawa. MD and Bruce Spring1 MD