[Analgesic abuse and psychiatric comorbidity in headache patients]

Headache patients frequently overuse analgesic medications: 20% of the patients from headache centers is concerned by this problem, which has been estimated to occur in four percent of the community migrainers. Frequent use of various types of headache medication may paradoxically cause an increase in headache attack frequency as well as their chronicisation due to potentially complex mechanisms of sensitization. Patients will enter into a self- perpetuating cycle of daily headaches and use of symptomatic medications which can lead to addiction and to social and occupational impairement. Indeed, many patients will experience pharmacological tolerance and dependence but also by some kind of craving. International Headache Society qualify these patients as abusers referring mostly to the amount of substance ingested. Hence patients are labelled analgesic abusers . However, as many of these analgesic medications contained psychotropic substances (i.e. caffeine, codeine.), these patients may fulfill DSM IV criteria of dependance. Nevertheless, the dependance criteria should be adapted to chronic pain patients. Indeed, if pharmacological dependence and tolerance criteria are easy to apply in such patients, it is not the case for the criteria a great deal of time spent to obtain substances, to use substances or to recover from substances effects . As analgesic medications are legally obtained from medical practitioners, drug seeking behaviours are mostly: obtaining medications from multiple providers, repeating episodes of prescription loss and multiplying requests for early refills. Moreover the detrimental effects of analgesic abuse on psychosocial functioning is likely to be related to pain rather than to medication overuse. Finally the best indicator of addictive behaviors in such patients, is the loss of control over the use of analgesic medication despite the adverse consequences over pain. Comorbidity with addiction to other substances has never been specifically scrutinized in this population, but it is well documented that chronic pain patients have high rates of addiction with various types of substances. Moreover, it is well documented that these patients are at higher risk for anxious (panic disorders and phobic disorders) and depressive disorders than non abusing headache patients. Anxiety and depressive scores are related to both the chronicity of headaches, and the amount of analgesic intake. Therefore, this comorbidity is possibly related to psychoactive substance use but there is no prospective study concerning chronological link between the anxious and depressive disorders and analgesic abuse. The presence of personality disorders in these patients is poorly documented, with the exception of neuroticism, which probably reflects the anxious and depressive comorbidity. Clinical findings show that a subgroup of patients needs an hospitalisation to succeed in withdrawal. They appears likely to be dependant on several types of drugs, to present with fear of pain itself, and to present with cluster B personality disorders, whereas another subgroup is specifically dependant on one type of drug, present with fear of pain induced impairement, and present with cluster C personality disorders. Those patients, when becoming aware of dependance, succeed in withdrawal at home, without the need of an hospitalization. The analgesic medication overuse and dependance can also be considered as a maladjusted strategy to manage pain (with prevalent passive and avoidant coping strategies). More research is required focusing on psychopathological aspects of analgesic overuse and dependance, to improve withdrawal modalities and to reduce the rate of relapses.