Date of Award

Fall 1-1-2025

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Psychology

First Advisor

Ahn, Woo-kyoung

Abstract

Lay and scientific communities alike increasingly attribute mental disorders to biological causes (e.g., genetic risk or neurobiological abnormalities). Biological explanations of mental disorders have some beneficial consequences, including reduced personal blame of individuals affected by such disorders. One adverse consequence, however, is that upon learning that a mental disorder has a biological etiology, people tend to show reduced trust in the effectiveness of psychotherapy. Given that the combination of psychotherapy and pharmacotherapy is often optimal for many mental disorders, reduced trust of psychotherapy could result in poorer clinical outcomes, if people elect not to receive such treatment. Although this distrust of psychotherapy for biologically explained mental disorders has been well-documented in the literature, no studies to date have offered strategies for mitigating this distrust. In this dissertation, I present five studies that together address this critical gap. In Study 1 (Chapter 2), I identify and empirically validate three erroneous beliefs hypothesized to underlie this distrust. These beliefs are that (1) mental activities, including psychotherapy, affect the brain less than they affect the mind, (2) biological processes are uncontrollable, and (3) psychosocial causes are less probable given biological causes. The extent that participants endorsed these beliefs correlated with the extent to which they judged psychotherapy to be less effective after learning about biological causes contributing to a case of depression. Identifying these beliefs was the first step towards providing targets for interventions to mitigate distrust of psychotherapy for biologically construed mental disorders. In Studies 2–4 (Chapters 3–5), I test three psychoeducational interventions to correct the beliefs identified in Study 1. These studies used the same general procedure, where participants learned about a hypothetical case of depression and then rated the effectiveness of psychotherapy for this case, at baseline and after learning that there were biological factors contributing to the symptom presentation (i.e., at post-test). Before providing post-test ratings of psychotherapy, participants assigned to the intervention condition in each study received, respectively, a reading passage explaining how 1) psychotherapy changes the brain (Study 2); 2) psychotherapy increases agency over biological processes (Study 3); 3) biological and psychosocial causes are often interdependent (Study 4). All three studies used a general population sample and a sample of individuals with symptoms of depression. In addition, Study 2 also included a sample of mental health clinicians. Across these studies and across the different samples, exposure to the intervention significantly lessened distrust of psychotherapy for biologically explained depression. Furthermore, these interventions each outperformed active control reading passages that emphasized 1) the effectiveness of psychotherapy, but without addressing how psychotherapy affects biological processes (Study 2); 2) how psychotherapy increases agency over symptoms, though not in relation to biological processes (Study 3); 3) that there are multiple psychosocial and biological causes of depression, but not how these causes interact (Study 4). ervention addressing all three beliefs. This study used the same procedures as in Studies 2–4, except that Study 5 also tested the durability of the video intervention in that participants were queried about the effectiveness of psychotherapy four weeks after receiving the intervention, without any reminders of its content in the interim. There was also an active control condition where participants received a video comprising content from the active control passages presented in Studies 2–4. Immediately after receiving the video intervention, participants judged psychotherapy to be significantly more effective, and this increase was significantly greater than that observed among active control condition participants. Furthermore, at follow-up, participants who received the intervention still showed no distrust of psychotherapy, whereas active control participants showed significantly reduced trust, relative to their baseline ratings, four weeks earlier. Together, the findings from these studies offer several strategies for intervening on the clinically detrimental belief that psychotherapy cannot effectively treat psychological disorders attributed to biological factors. This research is the first to develop such strategies, which also offer durable benefit and real-world applicability. Extensions of this program of research include testing the effect of these interventions in clinical settings and examining whether these interventions mitigate distrust of psychotherapy for other health conditions, beyond depression.

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