Unwanted effects of hypnosis: a review of the evidence and its implications

Mapping Knowledge Landscapes and Evolving Trends of Clinical Hypnotherapy Practice: A Bibliometrics-Based Visualization Analysis

Background and Aims

Increasing interest in hypnotherapy's application for a wide range of health conditions has spurred a rise in global research and publications. This study aims to visualize development patterns and current research hotspots in clinical hypnotherapy practice using scientometric methods, and to predict future research directions based on the keyword trending topics analysis.

Methods

Data on hypnotherapy applications and mechanisms in clinical settings between 1994 and 2023 were gathered from Scopus, Web of Science, and PubMed, followed by analysis and visualization using the VOSviewer, Bibliometrix package in R, and CiteSpace.

Results

A total of 1,549 publications were examined, indicating a steady annual increase with an average growth rate of 8.5%, reaching a high of 134 publications in 2022. The United States was the primary research hub. Collectively, 1,464 distinct institutions involving 3,195 scholars contributed to this research theme. Collaboration was predominantly confined to the same country, institution, and/or research team. High-frequency keywords included "Pain", "Irritable Bowel Syndrome (IBS)", and "Anxiety". Systematic review and/or meta-analysis have emerged as favored research methods. fMRI and EEG were commonly used techniques for exploring the neuropsychological mechanisms underlying hypnotherapy. "Self-Hypnosis", "Virtual Reality", and "Meditation" were predicted as trending topics, indicating that patients' self-managed hypnosis practice, virtual reality hypnotherapy, and exploration of the variations in mechanisms between meditation and hypnotherapy might be emerging topics and/or future key research directions within the current field.

Conclusion

The use of hypnotherapy for diverse clinical issues, particularly pain, IBS, and comorbid anxiety, is garnering global attention. The evidence-based approach is widely used to assess the quality of clinical evidence for hypnotherapy. Researchers are keen on innovating traditional hetero-hypnosis, with a shift towards more cost-effective self-hypnosis and immersive virtual reality hypnotherapy. Promoting and reinforcing collaborative research efforts across countries, institutions, and teams is warranted.

"Close your eyes and relax": the role of hypnosis in reducing anxiety, and its implications for the prevention of cardiovascular diseases

Anxiety is the most common form of mental health disorder, affecting millions of people worldwide. Psychosocial interventions such as mindfulness and cognitive behavioral therapy (CBT) have been suggested as an effective treatment in the management of general anxiety and anxiety disorders, with emerging evidence also suggesting the effectiveness of hypnosis. Moreover, anxiety has shown to be linked to the onset and development of several cardiovascular diseases (CVD), which are the leading cause of global death. In this paper, we review the current literature to examine the role that anxiety has on the onset and development of CVD and summarize the current knowledge on the role that hypnosis and hypnotherapy have in reducing anxiety, also explaining how this can impact the cardiovascular system and the prevention of CVD. Review of the evidence suggests that hypnosis and hypnotherapy are effective in treating anxiety and may positively affect the heart and the cardiovascular system, reducing sympathetic activation and increasing parasympathetic tone, potentially preventing the onset of CVD related to increased sympathetic activation. However, further studies are required to further understand how hypnosis and hypnotherapy affect the cardiovascular system through investigation of the neurophysiological components of the hypnotic state and of the mind-body relationship. Healthcare systems should embed mental health screening in patients at risk of developing CVD as part of the clinical pathway and consider the role that hypnosis and hypnotherapy may play in the management of CVD.

Using hypnosis in clinical practice for the management of chronic pain: A qualitative study

BACKGROUND

Interventions used in chronic pain management do not routinely use clinical hypnosis (CH), despite evidence to suggest its effectiveness in improving pain outcomes. This study aimed to explore the beliefs and attitudes of clinicians' towards the implementation of CH in chronic pain management.

METHOD

We conducted a cross-sectional qualitative analysis following online CH training. Clinicians working in three tertiary pain clinics, were recruited to participate in the online training program and invited to focus groups following completion of the training to explore beliefs and attitudes towards CH and the training program.

RESULTS

We identified three themes regarding barriers and two themes regarding facilitators to implementation of CH. Barriers: (i) misconceptions about CH, (ii) reduced confidence in implementing CH, and (iii) concerns about integrating CH with current treatment frameworks. Facilitators: (i) change in knowledge and attitude following training and (ii) an openness to exploring the technique and skills. The online training program was evaluated as positive with two themes: (i) training structure and (ii) training credibility.

CONCLUSION

Successful implementation of CH requires the development of training programs that address existing misconceptions of CH, allow for knowledge and skills acquisition, and adapt to the contextual setting within which the intervention is implemented.

PRACTICAL IMPLICATIONS

Training of clinicians in the process and skills required to deliver clinical hypnosis for chronic pain should be supported to facilitate its successful implementation into clinical settings.

Meta-analytic evidence on the efficacy of hypnosis for mental and somatic health issues: a 20-year perspective

Introduction

Documented use and investigation of hypnosis spans centuries and its therapeutic use has received endorsement by multiple medical associations. We conducted a comprehensive overview of meta-analyses examining the efficacy of hypnosis to provide a foundational understanding of hypnosis in evidence-based healthcare, insight into the safety of hypnosis interventions, and identification of gaps in the current research literature.

Methods

In our systematic review, meta-analyses of randomized controlled trials on the efficacy of hypnosis in patients with mental or somatic health problems compared to any control condition published after the year 2000 were included. A comprehensive literature search using Medline, Scopus, PsycINFO, The Cochrane Library, HTA Database, Web of Science and a manual search was conducted to identify eligible reviews. Methodological quality of the included meta-analyses was rated using the AMSTAR 2 tool. Effect estimates on various outcomes including at least three comparisons (k ≥ 3) were extracted and transformed into a common effect size metric (Cohen's d). If available, information on the certainty of evidence for these outcomes (GRADE assessment) was obtained.

Results

We included 49 meta-analyses with 261 distinct primary studies. Most robust evidence was reported for hypnosis in patients undergoing medical procedures (12 reviews, 79 distinct primary studies) and in patients with pain (4 reviews, 65 primary studies). There was a considerable overlap of the primary studies across the meta-analyses. Only nine meta-analyses were rated to have high methodological quality. Reported effect sizes comparing hypnosis against control conditions ranged from d = -0.04 to d = 2.72. Of the reported effects, 25.4% were medium (d ≥ 0.5), and 28.8% were large (d ≥ 0.8).

Discussion

Our findings underline the potential of hypnosis to positively impact various mental and somatic treatment outcomes, with the largest effects found in patients experiencing pain, patients undergoing medical procedures, and in populations of children/adolescents. Future research should focus on the investigation of moderators of efficacy, on comparing hypnosis to established interventions, on the efficacy of hypnosis for children and adolescents, and on identifying patients who do not benefit from hypnosis.

Clinical Trial Registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42023395514, identifier CRD42023395514.

Efficacy of Hypnosis in Adults Undergoing Surgical Procedures: A meta-analytic update

In this meta-analysis we updated a review from 2013 investigating the evidence on the efficacy of hypnosis in adults undergoing surgical procedures compared to standard care alone or an attention control. A comprehensive literature search using Medline, CENTRAL, Web of Science, PsycINFO, ProQuest Dissertations and Theses database, and manual searches were conducted to identify randomized controlled trials. In this update, N = 23 eligible studies were added to the existing study pool, resulting in N = 50 studies with 4269 patients. Random effects meta-analyses revealed positive treatment effects on mental distress (g = 0.55, 95% CI [0.39; 0.70], NNT = 3.32), pain (g = 0.37, 95% CI [0.25; 0.50], NNT = 4.78), medication consumption (g = 0.46, 95% CI [0.23; 0.68], NNT = 3.95), recovery (g = 0.26, 95% CI [0.09; 0.42], NNT = 6.91), and surgical procedure time (g = 0.23, 95% CI [0.14; 0.33], NNT = 7.6). No effects were found for physiological parameters (g = 0.13, 95% CI [-0.06; 0.33], NNT = 13.26). 95% prediction intervals included the null effect for all outcomes except for procedure time. In conclusion, although positive effects of hypnosis could be shown, overall generalizability is limited due to high heterogeneity of the study results that could not be explained by characteristics of patients, interventions, or study methods.

Promoting Safety in Hypnosis: A Clinical Instrument for the Assessment of Alertness

Hypnosis has long demonstrated its power to facilitate various approaches to psychotherapy. Like other potent modalities, hypnosis may produce unwanted effects. Although its negative sequelae are usually mild and transient, more serious complications may occur. Recently, attention has been drawn to the powerful role of failures of dehypnosis or alerting/realerting in producing unwanted effects. Traditionally, alerting has been viewed as a relatively uncomplicated process that requires little more than the simple suggestion that the subject will return or awaken from trance, and exiting from trance has generally been considered the cessation of the phenomena suggested during induction and thereafter. Newer findings challenge these assumptions and suggest that restoring the subject to a prehypnotic baseline level of alertness is of equal or greater importance. Here, I describe the Howard Alertness Scale (HAS), with which subjects can be made aware of their baseline levels of alertness to help them understand the unique ways that their trance states differ from their normal alert states, and assess and measure their subjective perception of alertness before and after hypnosis. Furthermore, regular use of the HAS holds potential to enhance both the therapeutic alliance and the patient's sense of safety and mastery. The development and use of the HAS is discussed along with three vignettes illustrating its clinical application.

Randomized trial of hypnosis as a pain and symptom management strategy in adults with sickle cell disease

Sickle cell disease (SCD) is the most common genetic disease in African-Americans, characterized by recurrent painful vaso-occlusive crises. Medical therapies for controlling or preventing crises are limited because of efficacy and/or toxicity. This is a randomized, controlled, single-crossover protocol of hypnosis for managing pain in SCD patients. Participants receive hypnosis from a trained hypnosis therapist followed by six weeks of self-hypnosis using digital media. Those in the control arm receive SCD education followed by a six-week waiting period before crossing over to the hypnosis arm of the study. Outcome measures include assessments of pain (frequency, intensity and quality), anxiety, coping strategies, sleep, depression, and health care utilization. To date, there are no published randomized, controlled trials evaluating the efficacy of hypnosis on SCD pain modulation in adults. Self-hypnosis for pain management may be helpful in modulating chronic pain, improving sleep quality, and decreasing use of narcotics in patients with SCD.

Hypnotherapy for labor and birth

Hypnotherapy is an integrative mind-body technique with therapeutic potential in various health care applications, including labor and birth. Evaluating the efficacy of this modality in controlled studies can be difficult, because of methodologic challenges, such as obtaining adequate sample sizes and standardizing experimental conditions. Women using hypnosis techniques for childbirth in hospital settings may face barriers related to caregiver resistance or institutional policies. The potential anxiolytic and analgesic effects of clinical hypnosis for childbirth merit further study. Nurses caring for women during labor and birth can increase their knowledge and skills with strategies for supporting hypnotherapeutic techniques.

Approaches to difficulties in realerting subjects from hypnosis

Recent studies have demonstrated the importance of identifying and addressing failures of realerting or dehypnosis. In parallel with the exploration of the adverse consequences of hypnosis in workshop settings, a number of techniques for effecting realerting subjects from hypnosis were collected. Some of these techniques are well-known, some were developed by applying techniques developed for other purposes to the task of realerting, and some were developed by the author when other known techniques proved unsuccessful or were rejected by subjects requiring dehypnosis. This article reports 15 techniques, three of which are foundational and designed to orient the subject to becoming realerted, and 12 more specific approaches to achieving dehypnosis. When appropriate, the particular opportunities of and the potential difficulties and relative contraindications for each technique are discussed.

Enhancing workshop safety: learning from colleagues' adverse experiences (part I--structure/content)

Recent studies demonstrate that unwanted responses to hypnosis during training workshops are not uncommon, and usually are covert (Kluft, 2012). Adverse events usually occurred subsequent to inadequate realerting from previous experiences of hypnosis. Inadequate realerting almost invariably was associated with unsuccessful permissive instructions for dehypnosis. Further, workshop faculty tended to accept partial dehypnosis as adequate dehypnosis. This article, the first of two related communications, offers 13 suggestions for minimizing workshops participants' risk of experiencing adverse events. It recommends safer replacements for techniques and stances often associated with adverse outcomes, and advocates using measures of alertness, such as the Howard Alertness Scale (Howard, 2008) to identify those at risk for unsuccessful realerting and the problems associated with it. Additional safety-related recommendations are communicated in Part II.

Inadvertent adverse consequences of clinical and forensic hypnosis: minimizing the risks

Hypnosis is a psychological intervention tool that can make a gamut of psychological, medical, and dental treatments work more rapidly and effectively. It can also be used profitably with some witnesses, victims, and defendants in forensic and investigative contexts as a data gathering tool. As with any other power tool, its use entails some risks. Since risks cannot be totally avoided, this article examines some ways to minimize the risks of inadvertent adverse or negative consequences as a result of the use of the hypnosis tool. Fundamentals of hypnosis risk management are covered as a foundation for beginners and as a review for experienced practitioners. Various straightforward safeguards that should be heeded by all practitioners are discussed.

Hypnosis in the Treatment of Dissociative Identity Disorder and Allied States: An Overview and Case Study

Hypnosis played a prominent role in the first successful treatment of the condition now known as dissociative identity disorder (DID) by Antoine Despine in the 1830s, and continues to be employed in its treatment in the twenty-first century. Despite its venerable history as a therapeutic modality for this condition, controversy has often compromised the acceptance of hypnosis by the healing professions. In this article, it will be argued that given the nature of hypnosis and that hypnotizability, a genetically mediated capacity, is high in dissociative disorder populations, it is inevitable that hypnosis will play a role in the treatment of DID patients, whether this is acknowledged or not. Thereafter, the roles hypnotically facilitated techniques might play will be reviewed, and the application of several of these techniques in the treatment of a DID patient will be illustrated.

Issues in the detection of those suffering adverse effects in hypnosis training workshops

Enhancing safety in hypnosis workshops is an issue of significant concern in the progress and promulgation of hypnosis as a facilitator of treatment. In general, hypnosis is a safe modality, but occasional adverse effects are encountered in its use in clinical, research, and professional workshop settings. To develop and implement modifications designed to reduce the number and/or severity of such unfortunate incidents in workshop settings, it is necessary to establish an awareness of the nature and implications of these adverse events. This article describes 9 categories of problem presentations known to have been generated in workshop settings. It also discusses a particular constellation of factors that--without imputing blame to either faculty or to workshop participants--creates powerful forces that minimize the likelihood that adverse effects will either be recognized by faculty or reported by workshop participants.

Positive affect, negative affect, and negative effects during a phenomenological hypnotic assessment within a substance abuse population

Positive and negative affect generated while using the Phenomenology of Consciousness--Hypnotic Assessment Procedure (PCI-HAP) on a sample of drug and alcohol users were predicted using several variables. The results were then cross-validated on a second, smaller sample. The results suggest that, although some negative affect was reported, the PCI-HAP was more likely to generate positive, rather than negative, affect. Positive affect was related to the vividness of a suggested hypnotic dream during hypnosis and also hypnotic depth; these findings were replicated upon cross-validation. Although negative affect correlated with the Dissociative Experiences Scale scores and falling asleep, these results did not replicate upon cross-validation. Mild transient negative effects (e.g., headache) were reported by about 10% of the participants in a smaller, second sample. Implications of the results are discussed.

Theory, methods and new directions in the psychophysiology of the schizophrenic process and schizotypy

Theoretical and methodological issues in the psychophysiology of the schizophrenic process are reviewed. These include the importance of schizotypy with its compensatory abilities as well as deficits for elucidating the processes of development and prevention of schizophrenia. The importance of individual differences, syndromes and single case studies. The recognition that this is a dynamic and fluctuating illness and hence the relevance of functional neurophysiology, including the role of imbalances in hemispheric activation in ontogeny, developmental course, expression of symptoms, the effects of neuroleptics and recovery process, and the influence of stress a precipitant of breakdown. The role of thalamo-cortical activation systems. The particular value of electrocortical measures including the interrelations of electroencephalographic rhythms throughout the spectrum, and relations of gamma, dynamic core neuronal complexity, connectivity and sensory gating with experiences of unreality and disturbances of consciousness.

Primum non nocere: thoughts on the need to develop an 'adverse events' register for complementary and alternative therapies

Building a body of knowledge to support the efficacy and practice of complementary and alternative therapies is an imperative that should be fully embraced by all those involved. Additional endeavours to monitor adverse events related to complementary and alternative therapies should also be pursued. The history and extent of medical iatrogenesis is briefly outlined, as is the literature on adverse events related to complementary and alternative therapies. Allopathic medicine is slowly realising the negative impact of iatrogenesis and is starting to develop systems to monitor such events in order to reduce or eliminate their existence. It is suggested that a similar development is needed in complementary and alternative therapies, so that it can be ensured that, at a minimum, primum non nocere, the therapy should firstly do no harm.