Over the past few decades, placebos have occupied an increasingly troublesome position in the medical world. Even as placebo-controlled trials have become accepted as the gold standard of evidence, we have come to realize how powerful the placebo effect can be. To further confuse matters, the new study extends an earlier finding: the placebo effect of antidepressant treatment appears to become stronger over time.
Previous studies had shown this to be happening with placebo pills. New research shows that’s happening with a treatment called transcranial magnetic stimulation. Fortunately, effective treatments appear to be improving in parallel, and this has not yet clearly affected outcomes.
stimulation magnet
transcranial magnetic stimulation It’s pretty simple in principle. Magnetic fields can be used to induce electrical currents in many materials. One of the substances in which it functions is the brain, where neural activity depends on the presence of voltage between cells and their environment. Therefore, by carefully shaping magnetic fields, it is possible to influence the activity of specific areas of the brain. Importantly, this can be performed using equipment placed outside the skull, making it very non-invasive compared to many other interventions.
However, this technology has many limitations. Targeting deep regions of the brain is difficult and somewhat imprecise. Targeting areas small enough to change only the behavior of neurons involved in a single process is difficult. Additionally, there are many options that allow you to change the length, intensity, and number of magnetic pulses created. Finding combinations that most effectively target and treat specific diseases requires significant effort.
Nevertheless, clinical trials are being conducted for various diseases, one of which is depression. And many of these have placebo controls. These include placing inactive hardware next to the skull and reorienting the magnetic field so that stimulation occurs next to the skull rather than under it.
But when it comes to depression, placebos have behaved a bit strangely over the past few decades, and since at least the 1980s, they’ve become even more potent. Many studies have shown that this is the case with pill-based placebos, and some studies suggest that this is true for transcranial magnetic stimulation as well. The new study aims to be a comprehensive meta-analysis large enough to test whether the improvement actually exists and figure out whether it is related to specific types of studies.
It gets better as time passes
The researchers began by pooling over 2,700 individual studies that used transcranial magnetic stimulation to treat depression. His selection of high-quality clinical trial data, including randomization and blinding, left only his 52 trials and a total of 4,500 participants, about half of whom received placebo treatment.
These placebos always contain hardware, but the hardware may not work or may be misdirected. Non-placebo treatments included various transcranial magnetic stimulation approaches.
Because it’s not really possible to do a placebo control for a placebo, this study simply focused on whether participants reported improvement in symptoms. And in fact, while the placebos were pretty consistently effective, the active treatment usually had a greater effect. (Using a measure called “magnitude of response,” the placebo was rated at 24 percent, while the actual treatment reached 38 percent.)
To find out whether the situation is changing over time, the researchers divided the trial into two batches, one covering 1999 to 2007 and the second covering 2018 to 2022. Targeted. Both placebo and treatment effects increased over time. . However, because the two were done in parallel, this change did not affect the results of the trial.
The researchers performed a regression analysis to examine which factors influenced these correlations. As expected, this analysis showed a correlation between the placebo effect and the effect of the actual treatment. Trials conducted in North and South America tended to have a greater impact, as did measures of risk of bias in each study.
Placebo is real
That doesn’t mean a placebo effect isn’t happening here. Researchers estimate that nearly 7,500 new studies showing no placebo effect would be needed for the placebo effect to completely disappear. However, this suggests that at least some of the differences between early and later trials may be due to study design. “Over the past 20 years, patient populations, transcranial magnetic stimulation protocols, equipment and techniques, sham procedures, and trial methods and conduct have all changed significantly,” the researchers note.
These are some of the things that could potentially influence how people perceive fake treatments. After all, the placebo effect is primarily mediated by the belief that some treatment is occurring. Transcranial magnetic stimulation, which involves medical staff and professional equipment placed next to a person’s head, lends itself well to that idea. If more efforts have been made in recent years to make placebos more convincing, it could easily explain the changes we’re seeing.
Unfortunately, the details of placebo treatment are often not reported in detail in studies, making it difficult to understand which specific changes are causing this effect.
Nature Mental Health, 2023. DOI: 10.1038/s44220-023-00118-9 (About DOI).