To the Editor.
—The conclusions by Dr Strain and colleagues1 that "caffeine exhibits the features of a typical psychoactive substance of dependence" should be viewed with reservation.The 16 subjects in the small study selected from a larger group of 99 adults with self-identified caffeine dependence clearly do not represent a cross section of the US population. Ten of the 16 had a previous substance abuse disorder (most commonly alcohol), two had a psychiatric diagnosis, and 14 of 16 were of the same sex. In addition, although subjects were not assessed for nicotine dependence, five were smokers who had a higher caffeine consumption than the nonsmokers.Obviously, caffeine consumption is markedly different from the use of drugs of abuse. For example, steadily increasing doses are generally not associated with caffeine ingestion and, of course, the destructive antisocial behavior provoked by drugs of abuse is clearly not associated with caffeine
Adamson RH, Roberts HR. Caffeine Dependence Syndrome. JAMA. 1995;273(18):1418. doi:10.1001/jama.1995.03520420029022