Placebo effects in alternative medical treatments for anxiety: false hope or healing potential?

Objective: This study investigated whether the perceived efficacy of healing crystals in reducing anxiety symptoms can be explained by classical conditioning mechanisms and belief-related cognitive biases, rather than genuine therapeutic effects. The aim was to disentangle placebo responses from true clinical outcomes in the context of pseudoscientific interventions. Methods: A sample of 138 adults from the general population was classified as either believers or non-believers in the efficacy of healing crystals. Participants were randomly assigned to an experimental group (rose quartz crystal) or a control group (placebo crystal), following a standardized 14-day usage protocol. Anxiety symptoms were assessed pre- and post-intervention using the Beck Anxiety Inventory and the Spanish version of the Kuwait University Anxiety Scale. A multilevel ANOVA and Bayesian analysis were conducted to evaluate main effects and interactions. Results: Significant reductions in anxiety were observed exclusively among believers, irrespective of whether they received the actual crystal or a placebo. No significant differences emerged between experimental and control groups, and the effects did not exceed those typically associated with placebo. Bayesian estimates further supported the null hypothesis for treatment effects. A strong correlation between pre-existing belief and perceived post-treatment efficacy suggested the presence of causal illusions shaped by classical conditioning. Conclusion: The findings indicate that healing crystals do not exert therapeutic effects beyond placebo. Observed symptom reductions were mediated by expectancy and conditioning mechanisms, particularly among participants prone to intuitive and magical thinking. Nevertheless, based on previous evidence, we do not rule out the possibility that this placebo effect could be amplified through interaction with other clinical variables associated with the therapeutic alliance in the doctor-patient relationship.