A subjective cognitive impairment scale for migraine attacks. The MIG-SCOG: Development and validation

Background: The burden of migraine is determined by impairment during attacks due to pain or non-painful symptoms such as cognitive symptoms. Objective: Development of a questionnaire to measure self-reported subjective cognitive symptoms during migraine attacks. Methods: Item generation was accomplished through structured patient interviews analysed by a panel of experts. A set of 43 candidate items was applied to consecutive migraine patients. Test construction with factor analysis retained nine items. Internal consistency was assessed with Cronbach's alpha and Spearman's rho, and convergent and construct validity by correlation to spontaneous cognitive complaints, and the 43-item and the Cognitive Failures Questionnaires. Results: The nine-item Mig-SCog covers two domains, executive functions and language. Cronbach's alpha was 0.82. It correlates with spontaneous cognitive complaints (p < 0.001), the 43-item (rho = 0.69) and the Cognitive Failures Questionnaires (rho = 0.61). Test-retest reliability (Cohen's kappa) was 0.55. Conclusions: Mig-SCog is a valid, reliable, consistent working instrument of fast self-administration that quantifies subjective cognitive symptoms during migraine attacks.