CAFFEINE SELF-ADMINISTRATION AND WITHDRAWAL - INCIDENCE, INDIVIDUAL-DIFFERENCES AND INTERRELATIONSHIPS

In four prior studies, caffeine (100 mg) self-administration was assessed by greater self-administration of caffeinated coffee than decaffeinated coffee and caffeine withdrawal was assessed by placebo substitution using six double-blind tests in each subject. This paper collates data across these studies to examine the incidence and predictors of the occurrence of caffeine self-administration and withdrawal. Caffeine self-administration occurred in 31% of subjects when a consistency criterion was used (n = 41) and 27% when a statistical criterion was used. Caffeine withdrawal occurred in 35% and 49% of subjects with each criteria (n = 37). Subjects who had withdrawal headaches and drowsiness were 2.3 - 2.6 times more likely to self-administer the caffeinated coffee. Several variables (e.g., average caffeine intake) did not predict caffeine self-administration or withdrawal.