Stress, caffeine and psychosis‐like experiences—A double‐blind, placebo‐controlled experiment

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AbstractObjectivePsychosis‐like perceptual distortions can occur in the general population, and both stress and caffeine can enhance the proneness to psychosis‐like experiences, such as hallucinations. The current study aims to explore the effects of acute caffeine intake and acute stress on perceptual distortions in a double‐blind, placebo‐controlled experiment.MethodsRegular caffeine consumers (n = 92) and non/low consumers (n = 89) were assigned to 100 mg caffeine/placebo and stress/no stress conditions. The White Christmas Paradigm (WCP) was used to measure hallucination‐like symptoms, and bias towards threat‐related words was used as an indicator of persecutory ideation. Participants reported their daily caffeine intake, and completed the State‐Trait Anxiety Inventory, the Launay‐Slade Hallucination Scale, the Persecutory Ideation Questionnaire and the Marlow‐Crowne Social Desirability Scale.ResultsAcute stress slightly increased hallucination‐like experiences, but not recall bias, while the small amount of caffeine had a time‐dependent effect on recall bias. Proneness to persecutory ideation was positively and social desirability was negatively correlated with recall bias towards threat‐related words, while proneness to hallucinations positively correlated with hallucination‐like experiences.ConclusionsOur results indicate that psychosocial stress—in line with the diathesis–stress model—can lead to the enhancement of hallucination‐like experiences.