Tardive dyskinesia (TD) is a drug-induced movement disorder that arises with antipsychotics. These drugs are the mainstay of treatment for schizophrenia. Epidemiological studies have shown mixed results on smoking's association with TD.

To study the association between smoking and TD induced by antipsychotics in outpatients with schizophrenia.

This was a cross-sectional study. It involved 89 patients suffering from schizophrenia, followed-up in outpatient psychiatry unit at Hédi Chaker university hospital in Sfax in Tunisia, between April and May 2016. We looked for TD in according to DSM-IV-R criteria. The intensity of TD was assessed with the Abnormal Involuntary Movement Scale (AIMS) and the level of nicotine dependence with the Fagerström Test for Nicotine Dependence (FTND).

The prevalence of smoking in patients with schizophrenia was 69.6%. Of these, 54.8% had a high or very high degree of nicotine dependence. The prevalence of TD was 33.7%. The AIMS average score was 12.13 ± 5.6 with extremes ranging from 3 to 26. TD was correlated with tobacco consumption (P = 0.003), the average number of smoked cigarettes (43.7 vs. 33.8; P = 0.004) and the Fagerström average score (7.2 vs. 6.1; P = 0.012).

The results of this study showed a correlation between the amount of smoking and severity of TD in patients with schizophrenia. The nature of the relationship between smoking and TD needs to be clarified through an experimental study.

The authors have not supplied their declaration of competing interest.