Smoking prevalence is highly elevated in schizophrenia compared to the general population and to other psychiatric populations. Evidence suggests that smoking may lead to improvements of schizophrenia-associated attention deficits; however, large-scale studies on this important issue are scarce. A group of psychiatrists from Berlin and biopsychologists from Bochum examined whether sustained, selective, and executive attention processes are differentially modulated by long-term nicotine consumption in 104 schizophrenia patients and 104 carefully matched healthy controls. Smoking was significantly associated with a detrimental conflict effect in controls, while the opposite effect was revealed for schizophrenia patients. Likewise, a positive correlation between a cumulative measure of nicotine consumption and conflict effect in controls and a negative correlation in patients were found. These results provide evidence for specific directional effects of smoking on conflict processing that critically dissociate with diagnosis. The data supports the self-medication hypothesis of smoking in schizophrenia and suggests selective attention as a specific cognitive domain positively targeted by nicotine consumption. The authors offer a model to explain the dissociating effects by nicotine-dopamine interactions located in the ventral tegmental area that lead to an increased prefrontal D1 receptor activation. As a consequence, smoking is disadvantageous for healthy participants with a priori favorable dopamine levels, but reinstates an advantageous D1 state in schizophrenia patients who otherwise suffer from a marked prefrontal dopamine deficit.

Hahn, C., Hahn, E., Dettling, M., Güntürkün, O., Ta, T.M.T., Neuhaus, A.H. (2012). Effects of smoking history on selective attention in schizophrenia. Neuropharmacology, 62, 1897-1902.