Reader response: Iron deposition in periaqueductal gray matter as a potential biomarker for chronic migraine

Biomarkers have not advanced comprehension of migraine pathophysiology, being unable to rationalize self-cycling onset and offset of migraine. These systemic diffuse brain deposits1,2 and nonlateralizing neuropeptides, from serotonin to calcitonin gene-related peptide, also face issues of blood-brain barrier crossing.