Vollesen ALH, et al. – In this randomized, double-blind, placebo-controlled, two-way crossover study, researchers assessed whether calcitonin gene-related peptide (CGRP) induces cluster headache attacks in active-phase episodic cluster headache (ECH), remission-phase ECH, and chronic cluster headache (CCH). They found that CGRP provokes cluster headache attacks in active-phase ECH and CCH but not in remission-phase ECH. Findings suggested that anti-CGRP drugs may be effective in the management of cluster headache.