How deeply one can hypnotize — known as hypnotizability — appears to be a stable trait that changes little throughout adulthood, like personality and IQ. But now, for the first time, Stanford Medicine researchers have shown a way to temporarily increase hypnotizability — potentially allowing more people to access the benefits of hypnosis-based therapy.
In the new study, to be published on January 4 Nature Mental Healthresearchers found that less than two minutes of electrical stimulation targeting a precise area of the brain could enhance participants’ hypnotizability for about an hour.
“We know that hypnosis is an effective treatment for many different symptoms and disorders, particularly pain,” said Afik Faerman, PhD, postdoctoral fellow in psychiatry and lead author of the study. “But we also know that not everyone benefits equally from hypnosis.”
About two-thirds of adults are at least somewhat hypnotizable, and 15% are considered highly hypnotizable, meaning they score a 9 or 10 on a standard 10-point measure of hypnotizability.
“Hypnosis is a state of highly focused attention, and higher hypnotizability improves your chances of doing better with techniques that use hypnosis,” said David Spiegel, MD, professor of psychiatry and behavioral sciences and senior author of the study.
Spiegel, the Jack, Lulu and Sam Willson Professor of Medicine, has spent decades studying hypnotherapy and using it to help patients control pain, reduce stress, quit smoking and more. Several years ago, Spiegel led a team that used brain imaging to uncover the neurobiological basis of the practice. They found that high hypnotizability subjects had stronger functional connectivity between the left dorsolateral prefrontal cortex, which is involved in information processing and decision making. and the dorsal anterior cingulate cortex, involved in stimulus detection.
“It made sense that the people who naturally coordinate activity between these two areas would be able to focus more closely,” Spiegel said. “It’s because you’re coordinating what you’re focusing on with the system that’s distracting you.”
Displacement of a fixed attribute
With these ideas, Spiegel collaborated with Nolan Williams, MD, associate professor of psychiatry and behavioral sciences, who has pioneered noninvasive neurostimulation techniques to treat conditions such as depression, obsessive-compulsive disorder, and suicidal ideation.
The hope was that neurostimulation could change even a stable trait like hypnotism.
In the new study, researchers recruited 80 participants with fibromyalgia, a chronic pain condition that can be treated with hypnotherapy. They excluded those who were already highly hypnotizable.
Half of the participants received transcranial magnetic stimulation, in which paddles applied to the scalp deliver electrical pulses to the brain. Specifically, they received two 46-second applications that delivered 800 pulses of electricity to a precise location in the left dorsolateral prefrontal cortex. The exact locations depended on each person’s unique brain structure and activity.
“A new aspect of this test is that we used the person’s own brain networks, based on brain imaging, to target the right spot,” said Williams, also senior author of the study.
The other half of the participants received a sham treatment that looked and felt the same, but without electrical stimulation.
Hypnotizability was assessed by the clinicians immediately before and after the treatments, without either the patients or the clinicians knowing who was in which group.
The researchers found that the participants who received the neurostimulation showed a statistically significant increase in sleepiness, about one degree higher. The sham group showed no effect.
When the participants were assessed again one hour later, the effect had disappeared and there was no longer a statistically significant difference between the two groups.
“We were pleasantly surprised that we were able, with 92 seconds of stimulation, to change a stable feature of the brain that people have been trying to change for 100 years,” Williams said. “We finally cracked the code on how to do it.”
The researchers plan to test whether different doses of neurostimulation could further enhance hypnotism.
“It’s unusual to be able to change the ability to hypnotize,” Spiegel said. A study of Stanford University students beginning in the 1950s, for example, found that the trait remained relatively consistent when the students were tested 25 years later, as consistent as IQ over that time period. Recent research from Spiegel’s lab also suggests that hypnotizability may have a genetic basis.
Clinically, a transient bump in hypnotizability may be enough to allow more people living with chronic pain to choose hypnosis as an alternative to long-term opioid use. Spiegel will contact study participants to see how they are doing in hypnotherapy.
The new results could have implications beyond hypnosis. Faerman noted that neurostimulation may be able to temporarily shift otherwise stable traits or enhance people’s response to other forms of psychotherapy.
“As a clinical psychologist, my personal vision is that, in the future, patients come in, go to a quick, non-invasive brain stimulation session and then go to see their psychologist,” he said. “Their benefit from treatment could be much higher.”
The study was supported by funding from the National Institutes of Health (grant R33AT009305-03).