title: Fourteen well-described caffeine withdrawal symptoms factor into three clusters.
abstract: BACKGROUND
  Abrupt cessation of caffeine often results in several withdrawal symptoms among habitual caffeine consumers.
  
  
  OBJECTIVE
  The objective of the study was to determine whether caffeine withdrawal symptoms co-exist as clusters in some individuals.
  
  
  METHODS
  Withdrawal symptoms and caffeine intake were assessed for men (n=126) and women (n=369), aged 20-29, using a caffeine habits questionnaire and a semi-quantitative food frequency questionnaire, respectively. Principal components factor analysis was used to identify common underlying factors among 14 well-described caffeine withdrawal symptoms. Odds ratios (OR) and 95% confidence intervals (CI) were calculated to determine if the likelihood of reporting a withdrawal factor was associated with habitual caffeine consumption.
  
  
  RESULTS
  The 14 withdrawal symptoms were grouped into three factors termed "fatigue and headache", "dysphoric mood", and "flu-like somatic". The likelihood of reporting the fatigue and headache and dysphoric mood factors increased with higher levels of habitual caffeine consumption. Compared to <100 mg/day of caffeine, the ORs (95% CI) of reporting the fatigue and headache factor with a habitual intake of 100-200 mg/day and >200 mg/day were 1.97 (1.21, 3.21) and 4.44 (2.50, 7.86), respectively. The corresponding ORs (95% CI) for the dysphoric mood factor were 1.55 (0.96, 2.52) and 3.34 (1.99, 5.60).
  
  
  CONCLUSIONS
  The 14 well-described caffeine withdrawal symptoms factor into three clusters, suggesting the existence of three distinct underlying mechanisms of caffeine withdrawal. Increasing habitual caffeine consumption is associated with an increased likelihood of reporting the fatigue and headache and dysphoric mood symptoms, but not the flu-like somatic symptoms.
authors.affiliation: Department of Nutritional Sciences, Room 350, University of Toronto, 150 College St, Toronto, ON, M5S 3E2, Canada.
authors.forename: Stephen
authors.initials: S
authors.lastname: Ozsungur
authors.forename: Darren
authors.initials: D
authors.lastname: Brenner
authors.forename: Ahmed
authors.initials: A
authors.lastname: El-Sohemy
mesh_terms: D000328:Adult; D002110:Caffeine / Q000008:administration & dosage / Q000009:adverse effects*; D000697:Central Nervous System Stimulants / Q000008:administration & dosage / Q000009:adverse effects*; D005260:Female; D006801:Humans; D016013:Likelihood Functions; D008297:Male; D016017:Odds Ratio; D025341:Principal Component Analysis; D013375:Substance Withdrawal Syndrome / Q000503:physiopathology*; D011795:Surveys and Questionnaires; D055815:Young Adult
chemical_list: D000697:Central Nervous System Stimulants; D002110:Caffeine
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