New research provides evidence that non-invasive brain stimulation techniques can help to make people more responsive to hypnosis. The findings, published in the International Journal of Clinical and Health Psychology, indicate that reducing neural excitability in a brain region known as the left dorsolateral prefrontal cortex tends to enhance hypnotizability.
Hypnosis has been shown promise as an intervention for a variety of mental health outcomes. For example, hypnosis can help some individuals to reduce symptoms of anxiety and depression by promoting relaxation and helping individuals to reframe negative thoughts.
“As a researcher, I was fascinated by the neurocognitive changes induced by hypnotic suggestions, while as a psychotherapist I was enthusiastic about the clinical benefits of some patients undergoing hypnotherapy. This is why I asked myself what I could do to enhance susceptibility of persons with low hypnotic responsiveness,” said study author Rinaldo L. Perri, the head of the Laboratory of Clinical and Experimental Neuropsychology at the University Niccolò Cusano in Rome, Italy.
The new study utilized inhibitory transcranial direct current stimulation (tDCS), a neurostimulation technique that uses low intensity direct current to modulate the activity of specific brain regions.
In inhibitory tDCS, the cathode electrode is placed over a specific area of the brain, while the anode electrode is placed elsewhere on the head. The current passing from the cathode to the anode reduces the excitability of the brain region under the cathode, making it less likely to fire and produce neural activity.
This effect can last for several minutes to hours after the stimulation is discontinued. Inhibitory tDCS is commonly used in research and clinical settings to study the effects of brain activity on various neurological and psychiatric conditions, such as depression, anxiety, and chronic pain.
The study involved 33 healthy volunteers recruited from a university student population. The participants were randomly assigned to either an active or sham group and underwent hypnotic induction with suggestions twice, before and after brain stimulation (or sham stimulation) over the left dorsolateral prefrontal cortex.
To assess subjective experiences of consciousness and hypnotic responsivity, the participants completed an assessment known as the Phenomenology of Consciousness Inventory – Hypnotic Assessment Procedure.
The researchers found that inhibitory tDCS enhanced hypnotizability by approximately 15% and altered dimensions of consciousness such as self-awareness and absorption.
“Hypnosis refers to a mental condition of increased absorption and reduced mind-wandering, and it is potentially beneficial for several applications such as analgesia, attentional and emotional regulation,” Perri told PsyPost. “Most people can experience hypnosis, but about 15% of the general population is estimated to be low hypnotizable. Findings from this study suggest that in the near future even those who are scarcely hypnotizable could enhance their hypnotic skills after a single session of tDCS.”
“In a recent reanalysis of the data, I was surprised to learn that low hypnotizables participants benefited most from non-invasive brain stimulation,” Perri explained. “On the contrary, non-invasive brain stimulation did not change the hypnotic experience of persons with high hypnotizability. This finding confirms the relevance of this line of research, as it suggests we can boost the hypnotic experience especially among refractory subjects.”
So what are some the next steps in this area of research?
“We still have to understand how to improve the susceptibility to specific hypnotic suggestions such as those involving imagery and perceptual regulation,” Perri explained. “My laboratory is working on it, and I am confident we will soon be able to test brain stimulation protocols that will enhance people’s self-regulatory abilities through hypnosis.”
“It is fundamental to promote a neuroscientific approach to hypnosis as there are still too many misconceptions affecting these procedures,” the researcher added. “I believe this line of research may have relevant implications for all hypnosis clients and practitioners. We welcome anyone to contribute to this project, so feel free to contact me for any information.”
The study, “Alteration of hypnotic experience following transcranial electrical stimulation of the left prefrontal cortex“, was authored by Rinaldo Livio Perri and Gloria Di Filippo.