Are Subjective Beliefs the Missing Link in Treatment Effectiveness Studies?

In the world of medical science, the efficacy of treatments like neurostimulation, neurofeedback, brain training, and pharmacotherapy is often measured by comparing the outcomes of active treatments against placebos. However, the new and innovative work of Luisa Fassi and her colleagues introduces a critical variable often neglected in such studies: the patient’s subjective beliefs and experiences.

Their analysis of four independent datasets involving 387 participants, including both clinical patients and healthy adults, reveals that an individual’s subjective beliefs about receiving active or placebo treatment can significantly influence the outcome of the treatment, often more so than the treatment itself.

This revelation by Fassi’s team, grounded in research across various age groups and conditions, challenges the traditional approach to evaluating treatment efficacy. It underscores the need for a paradigm shift in how clinical and non-clinical research is conducted and interpreted. By integrating participants’ subjective beliefs with objective treatment conditions, this study offers a more nuanced and comprehensive understanding of treatment efficacy, potentially revolutionizing the design and assessment of future interventions in neuroscience and psychiatry.

This study is about understanding how people’s beliefs about the treatment they receive can affect the outcomes of medical and psychological treatments. It’s particularly relevant in fields like neurostimulation (using electrical or magnetic stimulation on the brain), neurofeedback (brain training using real-time displays of brain activity), and pharmacotherapy (treatment using drugs).

In most experiments, researchers compare the effects of a real treatment (like a drug or a brain stimulation technique) with a placebo (a fake treatment, like a sugar pill). Traditionally, they’ve focused on the objective results—like how much a person’s symptoms improve. But this study suggests that what the person believes about the treatment they’re receiving (whether it’s real or a placebo) can be just as important, or even more so, in determining the results.

Specifically, this article discusses the impact of individual beliefs on the effectiveness of neuromodulation treatments like Transcranial Magnetic Stimulation (TMS) and electrical stimulation (tES). While these treatments have shown some promise in treating various conditions and enhancing mental processes, the research results have been inconsistent. A key overlooked factor is how much a person’s belief about whether they are receiving the actual treatment or a placebo (a fake treatment) influences the effectiveness of the treatment.

The article explains that in studies of TMS and tES, participants often report physical sensations that can make them guess if they’re getting the real treatment. To tackle this, researchers use sham (fake) treatments that mimic these sensations without actually affecting the brain. However, even with these sham treatments, the study suggests that a person’s belief about what treatment they are receiving (real or sham) can significantly impact the treatment’s effectiveness.

The researchers examined data from four studies involving clinical patients (people with health conditions) and healthy adults. These studies used different types of neurostimulation treatments. They found that people’s subjective experience—what they thought they were receiving—could explain the differences in how well they responded to treatment better than the actual treatment itself.

Study 1: Focused on patients with treatment-resistant depression who underwent Repetitive Transcranial Magnetic Stimulation (rTMS). Researchers found that participants’ beliefs about whether they were receiving active or sham (placebo) treatment significantly influenced their depression outcomes. Patients who believed they were receiving active treatment showed more improvement than those who thought they were receiving sham treatment, regardless of the actual treatment they received.

Study 2: Examined older adults with late-life depression treated with high-dose deep rTMS. Similar to Study 1, the beliefs of participants about the treatment they received (active or sham) affected their depression scores more than the actual treatment.

Study 3: Investigated home-based electrical stimulation (tDCS) treatment in adults with ADHD. The results indicated that participants who believed they were receiving active treatment showed more significant improvements in attention symptoms than those who believed they were receiving sham treatment. In this study, the actual (objective) treatment also significantly affected the outcomes.

Study 4: Extended the research to healthy participants, testing the effects of different doses of tDCS on mind-wandering. The study found that participants’ beliefs about the treatment type and stimulation strength (subjective dosage) significantly influenced their mind-wandering levels. The actual treatment (objective treatment) did not significantly affect the results.

Across all studies, the researchers observed that patients’ subjective beliefs about their treatment played a crucial role in the effectiveness of neurostimulation therapies. This suggests that in addition to the actual treatment, the perception and beliefs of patients about their treatment can significantly influence health outcomes.

Researchers have typically focused on whether participants could correctly guess if they received the actual treatment or a placebo to determine the success of the blinding in trials. This new research challenges this approach, suggesting that it’s not just about whether participants can guess the treatment correctly, but their individual beliefs about the treatment they think they’re receiving can also affect the results.

An interesting aspect of the study is considering the causal role of subjective beliefs. The researchers suggest that beliefs could influence experimental outcomes or vice versa, and they propose that future studies should collect data on subjective beliefs at multiple points to understand this relationship better. They also discuss the potential of telling all participants they are receiving active treatment to minimize the impact of beliefs on outcomes, though this raises ethical concerns.

The study’s approach could apply to other forms of treatment, like pharmacological studies and cognitive training. The researchers also hypothesize that subjective beliefs might affect more objective outcomes and neural functions, not just self-reported measures. They highlight a gap in current research practices, where many studies don’t record data on subjective beliefs, limiting understanding of their impact.

Overall, the study emphasizes the significant role of participants’ subjective beliefs and expectations in determining the outcomes of neurostimulation studies and potentially other forms of treatment. It suggests a need for more comprehensive data collection and analysis methods in future research to understand these effects fully.

 

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Fassi, L., Hochman, S., Daskalakis, Z. J., Blumberger, D. M., & Kadosh, R. C. (2020). The Importance of Individual Beliefs in Assessing Treatment Efficacy: Insights from Neurostimulation Studies. bioRxiv, 2020-12. (Link)