The effect of caffeine and stress on auditory hallucinations in a non-clinical sample

Both the diathesis-stress model and the continuum theory of schizophrenia attempt to explain the mechanism by which stress may facilitate the expression of the symptoms of schizophrenia in non-clinical samples. Caffeine has also recently been reported to increase proneness to hallucinate. In this study, 92 non-clinical participants were assigned to either a high or a low stress condition and a high or a low caffeine condition on the basis of self-report. After they had been primed, the participants were asked to listen to white noise and to report each time they heard the song "White Christmas" during the white noise. The song was never played. The results indicated that the interaction of stress and caffeine had a significant effect on the reported frequency of hearing "White Christmas". The results demonstrated that high caffeine levels in association with high levels of stressful life events interacted to produce higher levels of "hallucination" in non-clinical participants, indicating that further caution needs to be exercised with the use of this overtly "safe" drug. (C) 2011 Elsevier Ltd. All rights reserved.