Biochemical validation of self-reported caffeine consumption during caffeine fading.

Increasing concern about caffeine as a drug with potential for abuse has resulted in the development of procedures for effecting reductions in caffeine consumption among heavy users. However, the reliability of reported findings may be questioned, since previous studies have relied on subject self-report as the principal measure of caffeine use. The present study employed bioanalytic methods for assessing the reliability of self-reported caffeine intake during a caffeine-fading regime. Twelve subjects, each with a history of heavy caffeine use, provided baseline, treatment, and follow-up blood samples which were assayed for caffeine and its major metabolites. General support was provided for the reliability of self-report as a measure of caffeine consumption. The general efficacy of caffeine fading was also supported, although there were indications that maintenance effects may have been over-estimated in previous studies.