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Background: Schizophrenia is associated with very high rates of tobacco smoking. The latter may be related to an attempt to “self-medicate” symptoms and/or to alterations in function of high affinity nicotinic acetylcholine receptors (β2*-nAChRs). Methods: Smoking and nonsmoking subjects with schizophrenia (n=31) and age-, smoking- and sex-matched comparison subjects (n=31) participated in one [123I]5-IA-85380 single photon emission computed tomography (SPECT) scan to quantify β2*-nAChR availability. Psychiatric, cognitive, nicotine craving and mood assessments were obtained during active smoking as well as smoking abstinence. Results: There were no differences in smoking characteristics between smokers with and without schizophrenia. Subjects with schizophrenia had lower β2*-nAChR availability relative to comparison group, and nonsmokers had lower β2*-nAChR availability relative to smokers. However, there was no smoking by diagnosis interaction. Relative to nonsmokers with schizophrenia, smokers with schizophrenia had higher β2*-nAChR availability in limited brain regions. In smokers with schizophrenia, higher β2*-nAChR availability was associated with lower negative symptoms of schizophrenia and better performance on tests of executive control. Chronic exposure to antipsychotic drugs was not associated with changes in β2*-nAChR availability in schizophrenia. Conclusions: Although subjects with schizophrenia have lower β2*-nAChR availability as compared to comparison group, smokers with schizophrenia appear to upregulate in the cortical regions. Lower receptor availability in smokers with schizophrenia in the cortical regions is associated with a greater number of negative symptoms and worse performance on tests of executive function; suggesting smoking subjects with schizophrenia who upregulate to a lesser degree may be at risk for poorer outcomes.

Cerebral lateralization and localization of the M50 distinguished patients with schizophrenia from normal subjects. These findings suggest the possibility of anatomical displacement and/or disturbed organization of the primary sensory cortex in schizophrenia.

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