title: Caffeine as a risk factor for chronic daily headache: a population-based study.
abstract: 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 > or =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).
  
  
  CONCLUSIONS
  Dietary and medicinal caffeine consumption appears to be a modest risk factor for chronic daily headache onset, regardless of headache type.
authors.affiliation: Department of Preventive Medicine and Biometrics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Rd., Bethesda, MD 20814, USA. ascher@usuhs.mil
authors.forename: Ann I
authors.initials: AI
authors.lastname: Scher
authors.forename: Walter F
authors.initials: WF
authors.lastname: Stewart
authors.forename: Richard B
authors.initials: RB
authors.lastname: Lipton
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000700:Analgesics / Q000737:chemistry / Q000627:therapeutic use; D001628:Beverages; D002110:Caffeine / Q000009:adverse effects*; D016022:Case-Control Studies; D005260:Female; D020773:Headache Disorders / Q000188:drug therapy / Q000453:epidemiology* / Q000209:etiology; D006306:Health Surveys; D006801:Humans; D008297:Male; D008875:Middle Aged; D004364:Pharmaceutical Preparations; D012189:Retrospective Studies; D012307:Risk Factors; D014481:United States / Q000453:epidemiology
chemical_list: D000700:Analgesics; D004364:Pharmaceutical Preparations; D002110:Caffeine