Assessing Epistemic Trust in Common Mental Health Disorders: The Clinical Validation of ETMCQ, Measurement Invariance and Control Group Comparison

Epistemic trust is the capacity of an individual to assimilate new information and engage with their surroundings. This study focused on the Epistemic Trust, Mistrust, and Credulity Questionnaire (ETMCQ) among individuals seeking treatment for common mental health issues (<i>N</i> = 378) compared to a non-clinical group (<i>N</i> = 357). The study aimed to validate the ETMCQ clinically, assess its consistency across clinical groups and community controls, and explore the relationship between epistemic attitudes (trust, mistrust, and credulity), mentalizing, and mental health problems by comparing the two groups. The ETMCQ's three-factor structure showed acceptable reliability and validity in the clinical setting. The measurement invariance analyses showed complete metric consistency but only partial scalar and strict consistency, with certain items not aligning across groups (Items 1, 3, 4 for scalar consistency; 2, 12, 14 for strict consistency). The results indicated that difficulties in mentalizing and increased levels of epistemic trust, mistrust, and credulity were linked to a greater likelihood of experiencing clinical distress. These outcomes underline the effectiveness of the ETMCQ in distinguishing between clinical and non-clinical individuals. However, researchers should use caution with the epistemic trust component of the questionnaire which appears to reflect a paradoxical epistemic attitude.