Caffeine intake, toxicity and dependence and lifetime risk for psychiatric and substance use disorders: an epidemiologic and co-twin control analysis

ENGLISH :
BACKGROUND: Although caffeine is the most commonly used psychoactive substance and often produces symptoms of toxicity and dependence ; little is known ; especially in community samples ; about the association between caffeine use ; toxicity and dependence and risk for common psychiatric and substance use disorders. METHOD: Assessments of lifetime maximal caffeine use and symptoms of caffeine toxicity and dependence were available on over 3600 adult twins ascertained from the population-based Virginia Twin Registry. Lifetime histories of major depression (MD) ; generalized anxiety disorder (GAD) and panic disorder ; alcohol dependence ; adult antisocial behavior and cannabis and cocaine abuse/dependence were obtained at personal interview. Logistic regression analyses in the entire sample and within monozygotic (MZ) twin pairs were conducted in SAS. RESULTS: In the entire sample ; measures of maximal caffeine use ; heavy caffeine use ; and caffeine-related toxicity and dependence were significantly and positively associated with all seven psychiatric and substance use disorders. However ; within MZ twin pairs ; controlling for genetic and family environmental factors ; these associations ; while positive ; were all non-significant. These results were similar when excluding twins who denied regular caffeine use. CONCLUSIONS: Maximal lifetime caffeine intake and caffeine-associated toxicity and dependence are moderately associated with risk for a wide range of psychiatric and substance use disorders. Analyses of these relationships within MZ twin pairs suggest that most of the observed associations are not causal. Rather ; familial factors ; which are probably in part genetic ; predispose to both caffeine intake ; toxicity and dependence and the risk for a broad array of internalizing and externalizing disorders. (Author' s abstract)