Using brain scans in fibromyalgia patients under hypnotic induction, researchers found that the technique produces changes in underlying neural activity related to the effects of suggestion, and the mechanism of response in patients differed from that seen in controls — even though their behavioural response was similar. The study, “Suggestions to Reduce Clinical Fibromyalgia Pain and Experimentally Induced Pain Produce Parallel Effects on Perceived Pain but Divergent Functional MRI–Based Brain Activity.” is published in the journal ‘Psychosomatic Medicine’.
Targeted suggestions after a hypnotic induction are well established in clinical practice and have been increasingly used as a research tool in cognitive neuroscience. In particular, several reviews and meta-analyses have demonstrated the efficacy of hypnotically suggested analgesia in reducing chronic pain, acute surgical pain, and acute nonsurgical pain.
Approximately 75% of the population report significant pain reduction after hypnotic analgesia suggestion for both clinical and experimentally induced pain, regardless of its source. In some patients, hypnotic suggestion can have a significant effect on pain experience allowing surgery, childbirth, or bone marrow aspiration without further anaesthetic intervention.
Stuart W.G. Derbyshire, PhD, with the NUS Department of Psychology in Singapore, and his colleagues evaluated 13 fibromyalgia patients who received suggestions to alter their clinical pain, and 15 healthy controls who received suggestions to alter experimental heat pain. Suggestions were delivered before and after hypnotic induction, with blood oxygen level–dependent (BOLD) activity measurements taken at the same time. BOLD is a method used in functional magnetic resonance imaging (fMRI) to observe activity in different areas of the brain or other organs.
Both controls and patients reported large changes in pain experience after hypnotic and non-hypnotic suggestions of increasing or decreasing pain experience, although hypnotic suggestions produced larger changes and the added benefit of hypnotic suggestion trended toward significance overall, according to the authors.
There was also a significant interaction between hypnosis and suggestion, with lower pain ratings following suggestions to reduce pain delivered under hypnosis. Surprisingly, though, BOLD response increased in patients with pain report in regions previously associated with pain, including thalamus and anterior cingulate cortex. In controls, BOLD response decreased with pain report. All changes were greater after hypnotic induction.
According to the authors, “these findings imply that induction has an important effect on underlying neural activity mediating the effects of suggestion; the pattern of BOLD activity in the controls differs substantially from that observed in the patients. That difference implies a very different mechanism of suggestion in controls compared with patients, which would not have been evident from the behavioural data.”
by Daniela Semedo PhD, for the BSCH AW20016 newsletter
Daniela holds a PhD in Clinical Psychology from The University of Edinburgh, a MSc in Health Psychology and a BSc in Clinical Psychology. Her work has been focused on vulnerability to psychopathology and early identification and intervention in psychosis.
Suggestions to Reduce Clinical Fibromyalgia Pain and Experimentally Induced Pain Produce Parallel Effects on Perceived Pain but Divergent Functional MRI-Based Brain Activity.
Hypnotic suggestion is an empirically validated form of pain control; however, the underlying mechanism remains unclear.
Thirteen fibromyalgia patients received suggestions to alter their clinical pain, and 15 healthy controls received suggestions to alter experimental heat pain. Suggestions were delivered before and after hypnotic induction with blood oxygen level-dependent (BOLD) activity measured concurrently.
Across groups, suggestion produced substantial changes in pain report (main effect of suggestion, F2, 312 = 585.8; p < .0001), with marginally larger changes after induction (main effect of induction, F1, 312 = 3.6; p = .060). In patients, BOLD response increased with pain report in regions previously associated with pain, including thalamus and anterior cingulate cortex. In controls, BOLD response decreased with pain report. All changes were greater after induction. Region-of-interest analysis revealed largely linear patient responses with increasing pain report. Control responses, however, were higher after suggestion to increase or decrease pain from baseline.
Based on behavioral report alone, the mechanism of suggestion could be interpreted as largely similar regardless of the induction or type of pain experience. The functional magnetic resonance imaging data, however, demonstrated larger changes in brain activity after induction and a radically different pattern of brain activity for clinical pain compared with experimental pain. These findings imply that induction has an important effect on underlying neural activity mediating the effects of suggestion, and the mechanism of suggestion in patients altering clinical pain differs from that in controls altering experimental pain. Patient responses imply that suggestions altered pain experience via corresponding changes in pain-related brain regions, whereas control responses imply suggestion engaged cognitive control.
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