LE3 .A278 2014

2014

Potter, Susan

Acadia University

Bachelor of Science

Honours

Psychology

Psychology

The present study examined various psychological factors that were proposed to influence greater placebo responding in individuals with symptoms of anxiety, depression, and ADHD. 14 adults and 7 children consumed probiotics or placebo daily for several weeks (5 weeks for adults, 4 for children). At the beginning and end of this period (Times 1 and 2, respectively), participants completed a variety of measures assessing their mental health (i.e., the Anxiety Sensitivity Index, among others). Also, at the start of this period, participants completed the Placebo Response Prediction Questionnaire (PRPQ), which was comprised of various measures that assessed catastrophizing, expectations, somatic focus, and optimism. Pearson Correlations were used to analyze possible associations between PRPQ scores and changes in mental health measures for both intervention groups. As hypothesized, various PRPQ variables exclusively predicted placebo responding. Increased scores on catastrophizing measures showed significant positive correlations with changes in anxiety from Time 1 to Time 2 for adults in the placebo condition but not in the probiotic condition. Interestingly, pre-treatment expectations towards symptom relief in the placebo group showed a significant negative correlation with changes in the Cognitive Concerns subscale of the ASI, a finding that was opposite to what was previously hypothesized. The findings of this study indicate a probable interaction between expectations and catastrophizing during psychiatric treatment, and may have important implications in the design of future clinical trials.

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https://scholar.acadiau.ca/islandora/object/theses:1172