Caffeinism associated with greater use of other psychotropic agents.

C AFFEINISM, a diagnosis recently included in the third edition of the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders (DSM-III),’ is characterized by a constellation of affective, sleep, and psychophysiological manifestations.2 Because symptoms of caffeinism might be confounded or masked by simultaneous ingestion of other drugs, it is pertinent to ask whether high consumers of caffeine differ from low or moderate consumers in their use of other psychoactive agents. Few data are currently available to answer this question. Historically, 18th-century physicians suggested that tea and coffee consumption promoted later use of alcohol, opium, and other stimulants.3 Such claims were never proven. In contrast, increased cigarette smoking has been conclusively associated with high caffeine consumption.4-7 Although Greden et al.’ noted that a greater proportion of high caffeine consumers reported use of minor tranquilizers when compared with low or moderate caffeine users, few or no studies have described patterns of use for hypnotics, neuroleptics, antidepressants, or lithium among subgroups of caffeine users. The importance of documenting possible interactions between use of caffeine and use of other drugs increased with several recent discoveries. First, caffeine was shown to interact in vitro with a number of neuroleptics to form flaky precipitates and thus possibly impair the efficacy of these agents.8,9 Second, caffeine clinically antagonizes barbiturates” and monoamine oxidase inhibitors (MAOI).” Third, caffeine and caffeine withdrawal have been noted to alter adrenergic and serotonergic transmission, and thus may interfere with expected results from common psychiatric medications.‘.” Finally, following the exciting discovery that the brain contained specific receptors for benzodiazepines, it was noted that caffeine was a competitive inhibitor of diazepam binding to these brain receptors.‘3,‘4 Conceivably, competitive interference