Negative symptom clue to smoking in schizophrenia patients

By Lucy Piper, Senior medwireNews Reporter

Patients with schizophrenia may have a preponderance to cigarette smoking because it reduces negative symptom severity, researchers report.

They found in two large independent samples that Chinese men with schizophrenia were more than twice as likely to smoke cigarettes as their peers without schizophrenia, and half as likely to quit smoking.

Smoking among the combined 1139 male patients with schizophrenia was found to be consistently and significantly associated with reduced negative symptoms on the Positive and Negative Syndrome Scale, and remained so even after taking into account antipsychotic use.

This was the only one of the five dimensions of symptomatology measured that was significantly reduced, however. Smoking had no effect on positive, cognitive, or depressive symptoms, overall, and although it seemed to increase excitement in the two samples combined, the association was not significant in the individual study samples.

“These observations support the hypothesis that smoking alleviates negative symptoms in schizophrenia patients, which may account for the heavier smoking pattern among schizophrenia patients,” say lead researcher Jimmy Lee (Institute of Mental Health/Woodbridge Hospital, Singapore) and colleagues.

Their results showed that 42.4% of patients with schizophrenia were current smokers, compared with 16.8% of 535 individuals from the general population. The lifetime prevalence was 54.1% versus 29.3%.

In contrast to the theory that patients may smoke to reduce the side effects of their antipsychotic treatment, smoking was not associated with the use of antipsychotics or their side effects.

“Although smoking has a wide range of well-established ill effects on human health, these findings do raise the possibility of exploring nicotinic pathways for novel treatments of schizophrenia,” Lee and team write in PLoS One.

They note that transdermal nicotine treatment has previously been shown to improve short-term cognitive function in non-smoking schizophrenia patients.

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