Rozen TD - Researchers presented the results from the United States Cluster Headache Survey comparing the clinical presentation of tobacco nonexposed and tobacco-exposed cluster headache patients. Compared to the tobacco-exposed subgroup, there appeared a unique presentation of cluster headache sufferers who were never exposed to tobacco (personal or secondary as a child). In terms of attack frequency, cycle duration, and headache-related disability, the tobacco-exposed clinical phenotype appeared to have a more severe syndrome. Cluster headache chronification was observed in association with tobacco exposure. Compared to tobacco exposed sub-form, the nonexposed subtype appeared to have an earlier age of onset, higher rate of familial migraine, and less circadian periodicity and daytime entrainment, suggesting a possible different underlying pathology.