Background: Medication Overuse Headache (MOH) is a type of chronic headache, whose mechanisms are still unknown. Some empirical investigations examining the addiction-like behaviors and processes, as well as personality characteristics underlying MOH development, reached contrasting findings. This study aimed at detecting personality and its disorders (PDs) in MOH patients, with a specific attention to the features of addiction. Methods: Eighty-eight MOH patients have been compared with two clinical populations including 99 patients with Substance Use Disorder (SUD) and 91 with PDs using the Shedler-Westen Assessment Procedure-200 (SWAP-200). MANCOVAs were performed to evaluate personality differences among MOH, SUD and PD groups, controlling for age and gender. Results: MOH patients showed lower traits of the SWAP-200’s clusters A and B disorders than SUD and PD patients, whom presented more severe levels of personality impairment. No differences in the SWAP-200’s cluster C have been found, indicating common personality features in these populations. At levels of specific PDs, MOH patients presented higher obsessive and dysphoric traits, as well as better overall psychological functioning than SUD and PD patients. Conclusions: The study supported the presence of a specific pattern of personality in MOH patients including obsessive (perfectionist) and dysphoric characteristics, as well as good enough psychological resources. No similarities with drug addicted and personality-disordered patients were found. Practitioners’ careful understanding of the personality of MOH patients may be useful to provide more effective treatment strategies and patient-tailored intervention programs
