[Addictive behaviour in medication overuse headache: A review of recent data].

INTRODUCTION: Some data in the current medical literature suggests a link between medication overuse headache (MOH) and addictive behaviors. We present here a review of the clinical and biological data highlighting the role of addictive behaviors in MOH.

RESULTS: One third to one half of MOH patients will relapse in their overuse within five years following withdrawal of the offending medication. Some studies have shown that two thirds of MOH patients fulfil DSM-IV criteria for dependence concerning their use of acute headache medication. Moreover, there is a co-morbidity between substance related disorders and MOH and some data suggest a familial co-transmission between MOH and substancerelated disorders. In a prospective study, the use of acute headache medication containing psychoactive substances like opiate derivates increase the risk of transformation from an episodic headache to MOH suggesting the role of conditioning factors among other psychological variables as catastrophizing and a low self-efficacy. Finally, data from the neuroimagery, biology and genetic fields suggest the presence of common pathophysiological features between MOH and addiction. In particular, a study found a hypometabolism in the prefrontal cortex of MOH patients, not recovering after withdrawal, such abnormality being described in addicted patients and suggesting an inability of the prefrontal cortex to inhibit craving.

PERSPECTIVES: All these data suggest that with MOH we face two sets of patients. The first one, in which medication overuse is mainly due to the worsening of the headache course, with minimal psychiatric contribution ; the second one, in which addictive behavior can play a major role. In the first case, education can simply lead to a significant reduction of medication intake, whereas in the second case a pluridisciplinary follow-up must be proposed before, during and after acute headache detoxification.

CONCLUSION: A pluridisciplinary approach is the only way to reduce the relapse rate which remains too high in MOH.