Orbitofrontal dysfunction predicts poor prognosis in chronic migraine with medication overuse

Chronic migraine patients are at risk of developing a medication overuse. Brain functional studies in these patients have demonstrated an orbitofrontal hypometabolism, persistent after overuse cessation. Orbitofrontal dysfunction is also present in addiction and thus could predispose migraineurs to medication overuse. The aim of this study was to investigate if orbitofrontal dysfunction can be demonstrated in patients with chronic migraine and medication overuse by performing a systematic neuropsychological evaluation focused on tests that assess frontal lobe function. Second, to establish whether it is related to the outcome of these patients. We prospectively studied 42 chronic migraine patients with medication overuse, 42 episodic migraineurs and 41 controls on a battery of neuropsychological tasks evaluating the orbitofrontal and dorsolateral functioning. Depression, anxiety, and personality traits were also assessed. Chronic migraineurs with medication overuse showed a significant impairment in orbitofrontal task performance and higher depression scores as compared to episodic migraineurs and controls. Dorsolateral dysfunction was present in both groups of migraneurs, who also had higher rates of anxiety as compared to controls. After 1 year of follow-up, migraine patient’s outcome was classified according to their medication overuse status. A negative outcome that included persistent or new-onset medication overuse was present in 34% of migraineurs and was associated with baseline poor orbitofrontal task performance, and with mild dorsolateral dysfunction, higher rates of depression, anxiety and neuroticism-anxiety traits. Formal education and years with migraine did not influence outcome. Orbitofrontal dysfunction is present in patients with chronic migraine and medication overuse, and associates with a poor outcome at 1 year of follow-up. Neuropsychological evaluation in migraine may help to detect patients prone to overuse so that appropriate therapeutic attitudes can be taken. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s10194-011-0340-6) contains supplementary material, which is available to authorized users.