Initial credibility and expectancy ratings of a self-applied neurostimulation and cognitive training intervention for depression

Background
The DiSCoVeR Trial: ‘Examining the synergistic effects of a cognitive control videogame and a self-administered non-invasive brain stimulation on alleviating depression’ is a multi-site, double-blind, sham-controlled randomized clinical trial investigating the feasibility and efficacy of a self-applied intervention combining transcranial direct current stimulation (tDCS) with a cognitive control-enhancing video game in individuals with major depressive disorder (MDD). Prior to transitioning to home-based treatment, participants receive up to five supervised sessions. This analysis explores participants’ initial perceptions of the treatment’s credibility and expectancy using the Credibility/Expectancy Questionnaire (CEQ).
Methods
Participants completed the CEQ at the end of their fifth supervised treatment session. The questionnaire includes both cognitive and affective components assessing beliefs and feelings about treatment effectiveness and anticipated outcomes. Responses were collected on 9-point Likert scales and 0–100% probability scales. Descriptive statistics were calculated for each item to evaluate general trends in credibility and expectancy ratings.
Results
A total of 100 participants were included in the analysis. Ratings of perceived logic (M = 6.05, SD = 1.96) and usefulness of the therapy when thinking about it (M = 4.85, SD = 1.77) were moderately high. Participants reported a moderate level of confidence in recommending the therapy (M = 5.01, SD = 2.15). Expected improvement by the end of treatment, based on cognitive appraisal, averaged 40.4%. Affective responses were slightly lower, with emotional belief in the therapy’s usefulness rated at 4.27 (SD = 2.03) and emotional expectation of improvement averaging 34.9%. Median responses across all items reflected moderate perceived credibility and modest outcome expectancy.
Discussion
Initial assessments suggest that participants find the DiSCoVeR intervention logical and somewhat useful, with moderate expectations of improvement. Interestingly, emotional (affective) ratings were consistently lower than cognitive ones, reflecting a common pattern in credibility/expectancy measures where patients may intellectually endorse a treatment while feeling less confident emotionally. These findings support the feasibility of the intervention and underscore the importance of monitoring both cognitive and emotional engagement with novel treatment modalities in depression.
References:
[1] Dechantsreiter, E., Padberg, F., Morash, A., Kumpf, U., Nguyen, A., Menestrina, Z., Windel, F., Burkhardt, G., Goerigk, S., Morishita, T., Soldini, A., Ahissar, S., Cohen, T., Pasqualotto, A., Rubene, L., Konosonoka, L., Keeser, D., Zill, P., Assi, R., Gardier, R., Viñals, R., Thiran, J., Segman, R., Benjamini, Y., Bonne, O., Hummel, F., Bavelier, D., Rancans, E., Nahum, M., 2023. Examining the synergistic effects of a cognitive control video game and a home-based, self-administered non-invasive brain stimulation on alleviating depression: the DiSCoVeR trial protocol. European Archives of Psychiatry and Clinical Neuroscience Volume 273, Issue 1, Pages 85 – 98
[2] Devilly, G.J., Borkovec, T. D., 2000. Psychometric properties of the credibility/expectancy questionnaire. J Behav Ther Exp Psychiatry 31(2), 73-86