Increased levels of the nicotine metabolite cotinine in schizophrenic smokers compared to other smokers.

The purpose of this study was to determine if schizophrenic patients self-administer more nicotine during cigarette smoking than nonschizophrenic subjects. Urinary cotinine, a nicotine metabolite, was measured in 20 schizophrenic patients and 20 nonschizophrenic subjects with similar smoking history. Schizophrenic patients had significantly higher urinary cotinine levels, suggesting that schizophrenics consume higher doses of nicotine, probably by deeper inhalation of cigarettes. Schizophrenic patients' higher dose of nicotine may target different receptors than those activated by the lower doses self-administered by most nonschizophrenic smokers. In particular, high doses may activate low-affinity alpha-7 nicotinic receptors, associated with deficits in sensory inhibition in schizophrenia.