Caffeine as a risk factor for chronic daily headache: A population-based study

Objective: To investigate the possible association of dietary caffeine consumption and medicinal caffeine use with chronic daily headache (CDH). Methods: Population-based cases and controls were recruited from the Baltimore, MD, Philadelphia, PA, and Atlanta, GA, metropolitan areas. Controls (n = 507) reported 2 to 104 headache days/year, and cases (n = 206) reported ≥180 headache days/year. Current and past dietary caffeine consumption and medication use for headache were based on detailed self-report. High caffeine exposure was defined as being in the upper quartile of dietary consumption or using a caffeine-containing over-the-counter analgesic as the preferred headache treatment. Results: In comparison with episodic headache controls, CDH cases were more likely overall to have been high caffeine consumers before onset of CDH (odds ratio [OR] = 1.50, p = 0.05). No association was found for current caffeine consumption (i.e., post CDH) (OR = 1.36, p = 0.12). In secondary analyses, associations were confined to younger (age <40) women (OR = 2.0, p = 0.02) and those with chronic episodic (as opposed to chronic continuous) headaches (OR = 1.69, p = 0.01), without physician consultation (OR = 1.67, p = 0.04) and of recent (<2 years) onset (OR = 1.67, p = 0.03). Conclusion: Dietary and medicinal caffeine consumption appears to be a modest risk factor for chronic daily headache onset, regardless of headache type.