“Positive Expectations Predict Improved Mental-Health Outcomes Linked to Psychedelic Microdosing”, 2021-01-21 (; backlinks; similar):
Psychedelic microdosing describes the ingestion of near-threshold perceptible doses of classic psychedelic substances. Anecdotal reports and observational studies suggest that microdosing may promote positive mood and well-being, but recent placebo-controlled studies failed to find compelling evidence for this.
The present study collected web-based mental health and related data using a prospective (before, during and after) design. Individuals planning a weekly microdosing regimen completed surveys at strategic timepoints, spanning a core 4-week test period. 81 participants completed the primary study endpoint. Results revealed increased self-reported psychological well-being, emotional stability and reductions in state anxiety and depressive symptoms at the four-week primary endpoint, plus increases in psychological resilience, social connectedness, agreeableness, nature relatedness and aspects of psychological flexibility. However, positive expectancy scores at baseline predicted subsequent improvements in well-being, suggestive of a substantial placebo response. This study highlights a role for positive expectancy in predicting positive outcomes following psychedelic microdosing and cautions against zealous inferences on its putative therapeutic value.
…Due to the pragmatic challenges of doing so via an online observational study, the present study did not include a placebo control condition. We did, however, employ a prospective, naturalistic design that included baseline sampling of expectations about possible outcomes from the impending microdosing. Well-being, state anxiety and depressive symptom scores were measured weekly on five occasions (pre-dosing at baseline to week 4 of the microdosing regimen) in order to track time-dependent changes. Neuroticism/emotional stability was measured pre-dosing at baseline and post-dosing at week 4 only. It was predicted that well-being and emotional stability would be increased, and that depression and anxiety scores would be decreased, at the key-endpoint (4 weeks) compared with baseline. Capitalising on the nature of the prospective design, we also predicted that baseline positive expectations about microdosing would be related to any subsequent improvements in well-being, depressive symptoms and anxiety scores. Finally, exploratory analyses were performed to assess pre-post changes in a range of secondary psychological outcomes of interest.
…Expectancy effect on main outcome change scores: One-tailed partial correlations using Pearson coefficient were employed in order to investigate the effects of baseline expectations on endpoint change scores (endpoint—baseline) for the primary outcome variables (well-being, depressive symptoms and anxiety), whilst controlling for the corresponding baseline scores. In line with our main hypothesis, expectations for well-being improvement were statistically-significantly associated with change scores in well-being (r = 0.275 [d = −0.57], p = 0.007), depressive symptoms (r = −0.263 [d = −0.54], p = 0.009) and anxiety (r = −0.220 [d = −0.45], p = 0.025). These results indicate that baseline expectations were predictive of mental health change at the study endpoint.