The aim of the study was to explore the relationship between cutaneous pain thresholds, Zung Self-Rating Depression Scale (ZUNG-D) scores, Leeds Dependence Questionnaire (LDQ) scores and serum levels of apolipoprotein A1 (APOA1) and apolipoprotein E (APOE) in patients with MOH. This evidence concerns the gene APOE and major depressive disorder.