Jones Fernyhough 2009 Caffeine, Stress, and Proneness to...

Personality and Individual Differences 46 (2009) 562–564 Contents lists available at ScienceDirect Personality and Individual Differences journal homepage: www.elsevier.com/locate/paid Short Communication Caffeine, stress, and proneness to psychosis-like experiences: A preliminary investigation Simon R. Jones *, Charles Fernyhough Department of Psychology, Durham University, South Road, Durham DH1 3LE, UK a r t i c l e i n f o a b s t r a c t In diathesis–stress models of psychosis, cortisol released in response to stressors is proposed to play a role in the development of psychotic experiences. Individual differences in cortisol response to stressors are therefore likely to play a role in proneness to psychotic†¦show more content†¦study. 2. Method 2.1. Participants Students (N = 219, 154 women) at a United Kingdom university, with a mean age of 20.1 years (SD = 1.34, range = 18–28) were recruited through e-mail invitation. No ï ¬ nancial incentive was offered and the likelihood of repeated participation was thus considered low. Answers were given anonymously, with only the age, gender and weight of the participants being recorded. Cigarette smokers were excluded from the study. 2.2. Measures Participants completed the following questionnaires in the order stated below: Durham Caffeine Inventory (DCI): Caffeine was assessed utilising a new tool designed to assess caffeine intake in a contemporary UK student population. The DCI presents speciï ¬ c types of drink and food containing caffeine (see Table 1), of which participants rate their typical intake over the past year, using a 12-point response scale ranging from ‘‘none/less than one per week† to ‘‘8+ per day†. In addition to predeï ¬ ned categories (e.g., instant coffee, tea) participants are also asked about coffee purchased from coffee shops, other energy drinks, and caffeine tablets. Participants use the same response scale, but are free to enter the name of the beverage or make of tablets used. A full copy of the DCI is available upon request. Hallucination-proneness: This was assessed using the modiï ¬ ed Launay-Slade Hallucination Scale (LSHS-M: Laroi van der Linden, 2005), a 16-item instrument designed to measure predisposition to