This study aimed at determining the causes of failure of the different proposed strategies to ensure improvement of medication-overuse headache (MOH) patients, since they have not been investigated so far, especially with regard to aspects related to cognitive and behavioural aspects of symptomatic drugs overused by them. One hundred and twenty in-patients, 82 females (68.3 %), median age 49 (42–56) years, affected by MOH were admitted to the study and treated with abrupt discontinuation of the medication overused, a 6-day in-patient detoxification regimen and an immediate start of personalized prophylactic treatment, then followed for 1 year. Leeds Dependence Questionnaire (LDQ), among all the clinical variables, was administered at baseline and at 1-year follow-up visit to assess substance dependence. Of the 120 patients enrolled, 68 (56.7 %) were successfully detoxified (Responder-group), while 52 (43.3 %) were not (Non-Responder-group). At baseline, the mean LDQ total score was slightly higher in the Non-Responder group than in the Responder group (12.08 ± 2.14 vs. 11.94 ± 1.98). Although this difference was not significant at baseline (p > 0.05), the LDQ total score was significantly different (p < 0.001) at the 1-year follow-up visit between the responder group (7.8 ± 2.3) and the Non-Responder group (12.1 ± 2.1). Moreover, the pattern of the responses of the patients in the responder group differed from that of the Non-Responder-group in the items relating to the compulsion to start, compulsion to continue, primacy of effect, constancy of state and cognitive set. The results showed that patients of the Non-Responder group showed a drug dependence pattern similar to that previously described in addicts. Conversely, in patients who positively responded to the procedure, drug-abuse behaviour seemed to be a consequence of chronic headache, reflecting the need for daily analgesic use to cope with everyday life.