The climate of neurofeedback: scientific rigour and the perils of ideology

Increasing Value and Reducing Waste of Research on Neurofeedback Effects in Post-traumatic Stress Disorder: A State-of-the-Art-Review

Post-Traumatic Stress Disorder (PTSD) is often considered challenging to treat due to factors that contribute to its complexity. In the last decade, more attention has been paid to non-pharmacological or non-psychological therapies for PTSD, including neurofeedback (NFB). NFB is a promising non-invasive technique targeting specific brainwave patterns associated with psychiatric symptomatology. By learning to regulate brain activity in a closed-loop paradigm, individuals can improve their functionality while reducing symptom severity. However, owing to its lax regulation and heterogeneous legal status across different countries, the degree to which it has scientific support as a psychiatric treatment remains controversial. In this state-of-the-art review, we searched PubMed, Cochrane Central, Web of Science, Scopus, and MEDLINE and identified meta-analyses and systematic reviews exploring the efficacy of NFB for PTSD. We included seven systematic reviews, out of which three included meta-analyses (32 studies and 669 participants) that targeted NFB as an intervention while addressing a single condition-PTSD. We used the MeaSurement Tool to Assess systematic Reviews (AMSTAR) 2 and the criteria described by Cristea and Naudet (Behav Res Therapy 123:103479, 2019, https://doi.org/10.1016/j.brat.2019.103479 ) to identify sources of research waste and increasing value in biomedical research. The seven assessed reviews had an overall extremely poor quality score (5 critically low, one low, one moderate, and none high) and multiple sources of waste while opening opportunities for increasing value in the NFB literature. Our research shows that it remains unclear whether NFB training is significantly beneficial in treating PTSD. The quality of the investigated literature is low and maintains a persistent uncertainty over numerous points, which are highly important for deciding whether an intervention has clinical efficacy. Just as importantly, none of the reviews we appraised explored the statistical power, referred to open data of the included studies, or adjusted their pooled effect sizes for publication bias and risk of bias. Based on the obtained results, we identified some recurrent sources of waste (such as a lack of research decisions based on sound questions or using an appropriate methodology in a fully transparent, unbiased, and useable manner) and proposed some directions for increasing value (homogeneity and consensus) in designing and reporting research on NFB interventions in PTSD.

Neurofeedback on twitter: Evaluation of the scientific credibility and communication about the technique

Neurofeedback is a popular technique to induce neuroplasticity with a controversial reputation. The public discourse on neurofeedback, as a therapeutic and neuroenhancement technique, encompasses scientific communication, therapeutic expectations and outcomes, as well as complementary and alternative practices. We investigated twitter publications from 2010 to 2022 on the keyword "neurofeedback". A total of over 138 k tweets were obtained, which originated from over 42 k different users. The communication flow in the neurofeedback community is mainly unidirectional and non-interactive. Analysis of hashtags revealed application fields, therapy provider and neuroenhancement to be the most popular contents in neurofeedback communication. A group of 1221 productive users was identified, in which clinicians, entrepreneurs, broadcasters, and scientists contribute. We identified reactions to critical publications in the twitter traffic and an increase in the number of tweets by academic users which suggest an increase in the interest on the scientific credibility of neurofeedback. More intense scientific communication on neurofeedback in twitter may contribute to promote a more realistic view on challenges and advances regarding good scientific practice of neurofeedback.

Neurofeedback as placebo: a case of unintentional deception?

The use of placebo in clinical practice has been the topic of extensive debate in the bioethics literature, with much scholarship focusing on concerns regarding deception. While considerations of placebo without deception have largely centred on open-label placebo, this paper considers a different kind of ethical quandary regarding placebo without an intent to deceive-one where the provider believes a treatment is effective due to a direct physiological mechanism, even though that belief may not be supported by rigorous scientific evidence. This is often the case with complementary and alternative medicine (CAM) techniques and also with some mainstream therapies that have not proven to be better than sham. Using one such CAM technique as a case study-electroencephalography (EEG) neurofeedback for attention-deficit/hyperactivity disorder (ADHD)-this paper explores the ethics of providing therapies that may have some beneficial effect, although one that is likely due to placebo effect. First, we provide background on EEG neurofeedback for ADHD and its evidence base, showing how it has proven to be equivalent to-but not better than-sham neurofeedback. Subsequently, we explore whether offering therapies that are claimed to work via specific physical pathways, but may actually work due to the placebo effect, constitute deception. We suggest that this practice may constitute unintentional deception regarding mechanism of action. Ultimately, we argue that providers have increased information provision obligations when offering treatments that diverge from standard of care and we make recommendations for mitigating unintentional deception.

Infraslow closed-loop brain training for anxiety and depression (ISAD): a protocol for a randomized, double-blind, sham-controlled pilot trial in adult females with internalizing disorders

BACKGROUND

The core intrinsic connectivity networks (core-ICNs), encompassing the default-mode network (DMN), salience network (SN) and central executive network (CEN), have been shown to be dysfunctional in individuals with internalizing disorders (IDs, e.g. major depressive disorder, MDD; generalized anxiety disorder, GAD; social anxiety disorder, SOC). As such, source-localized, closed-loop brain training of electrophysiological signals, also known as standardized low-resolution electromagnetic tomography (sLORETA) neurofeedback (NFB), targeting key cortical nodes within these networks has the potential to reduce symptoms associated with IDs and restore normal core ICN function. We intend to conduct a randomized, double-blind (participant and assessor), sham-controlled, parallel-group (3-arm) trial of sLORETA infraslow (<0.1 Hz) fluctuation neurofeedback (sLORETA ISF-NFB) 3 times per week over 4 weeks in participants (n=60) with IDs. Our primary objectives will be to examine patient-reported outcomes (PROs) and neurophysiological measures to (1) compare the potential effects of sham ISF-NFB to either genuine 1-region ISF-NFB or genuine 2-region ISF-NFB, and (2) assess for potential associations between changes in PRO scores and modifications of electroencephalographic (EEG) activity/connectivity within/between the trained regions of interest (ROIs). As part of an exploratory analysis, we will investigate the effects of additional training sessions and the potential for the potentiation of the effects over time.

METHODS

We will randomly assign participants who meet the criteria for MDD, GAD, and/or SOC per the MINI (Mini International Neuropsychiatric Interview for DSM-5) to one of three groups: (1) 12 sessions of posterior cingulate cortex (PCC) ISF-NFB up-training (n=15), (2) 12 sessions of concurrent PCC ISF up-training and dorsal anterior cingulate cortex (dACC) ISF-NFB down-training (n=15), or (3) 6 sessions of yoked-sham training followed by 6 sessions genuine ISF-NFB (n=30). Transdiagnostic PROs (Hospital Anxiety and Depression Scale, HADS; Inventory of Depression and Anxiety Symptoms - Second Version, IDAS-II; Multidimensional Emotional Disorder Inventory, MEDI; Intolerance of Uncertainty Scale - Short Form, IUS-12; Repetitive Thinking Questionnaire, RTQ-10) as well as resting-state neurophysiological measures (full-band EEG and ECG) will be collected from all subjects during two baseline sessions (approximately 1 week apart) then at post 6 sessions, post 12 sessions, and follow-up (1 month later). We will employ Bayesian methods in R and advanced source-localisation software (i.e. exact low-resolution brain electromagnetic tomography; eLORETA) in our analysis.

DISCUSSION

This protocol will outline the rationale and research methodology for a clinical pilot trial of sLORETA ISF-NFB targeting key nodes within the core-ICNs in a female ID population with the primary aims being to assess its potential efficacy via transdiagnostic PROs and relevant neurophysiological measures.

TRIAL REGISTRATION

Our study was prospectively registered with the Australia New Zealand Clinical Trials Registry (ANZCTR; Trial ID: ACTRN12619001428156). Registered on October 15, 2019.

Attention neuroenhancement through tDCS or neurofeedback: a randomized, single-blind, controlled trial

Neurofeedback and transcranial Direct Current Stimulation (tDCS) are promising techniques for neuroenhancement of attentional performance. As far as we know no study compared both techniques on attentional performance in healthy participants. We compared tDCS and neurofeedback in a randomized, single-blind, controlled experiment assessing both behavioral (accuracy and time reaction) and electrophysiological (N1, P1, and P3 components) data of participants responding to the Attention Network Task (ANT). Eighty volunteers volunteered for this study. We adopted standard protocols for both techniques, i.e., a Sensorimotor Rhythm (SMR) protocol for neurofeedback and the right DLPFC anodal stimulation for tDCS, applied over nine sessions (two weeks). We did not find significant differences between treatment groups on ANT, neither at the behavioral nor at the electrophysiological levels. However, we found that participants from both neuromodulation groups, irrespective of if active or sham, reported attentional improvements in response to the treatment on a subjective scale. Our study adds another null result to the neuromodulation literature, showing that neurofeedback and tDCS effects are more complex than previously suggested and associated with placebo effect. More studies in neuroenhancement literature are necessary to fully comprehend neuromodulation mechanisms.

fMRI Brain Decoding and Its Applications in Brain-Computer Interface: A Survey

Brain neural activity decoding is an important branch of neuroscience research and a key technology for the brain-computer interface (BCI). Researchers initially developed simple linear models and machine learning algorithms to classify and recognize brain activities. With the great success of deep learning on image recognition and generation, deep neural networks (DNN) have been engaged in reconstructing visual stimuli from human brain activity via functional magnetic resonance imaging (fMRI). In this paper, we reviewed the brain activity decoding models based on machine learning and deep learning algorithms. Specifically, we focused on current brain activity decoding models with high attention: variational auto-encoder (VAE), generative confrontation network (GAN), and the graph convolutional network (GCN). Furthermore, brain neural-activity-decoding-enabled fMRI-based BCI applications in mental and psychological disease treatment are presented to illustrate the positive correlation between brain decoding and BCI. Finally, existing challenges and future research directions are addressed.

Neurofeedback for cognitive enhancement and intervention and brain plasticity

In recent years, neurofeedback has been used as a cognitive training tool to improve brain functions for clinical or recreational purposes. It is based on providing participants with feedback about their brain activity and training them to control it, initiating directional changes. The overarching hypothesis behind this method is that this control results in an enhancement of the cognitive abilities associated with this brain activity, and triggers specific structural and functional changes in the brain, promoted by learning and neuronal plasticity effects. Here, we review the general methodological principles behind neurofeedback and we describe its behavioural benefits in clinical and experimental contexts. We review the non-specific effects of neurofeedback on the reinforcement learning striato-frontal networks as well as the more specific changes in the cortical networks on which the neurofeedback control is exerted. Last, we analyse the current challenges faces by neurofeedback studies, including the quantification of the temporal dynamics of neurofeedback effects, the generalisation of its behavioural outcomes to everyday life situations, the design of appropriate controls to disambiguate placebo from true neurofeedback effects and the development of more advanced cortical signal processing to achieve a finer-grained real-time modelling of cognitive functions.

Neurotherapeutics for Attention Deficit/Hyperactivity Disorder (ADHD): A Review

This review focuses on the evidence for neurotherapeutics for attention deficit/hyperactivity disorder (ADHD). EEG-neurofeedback has been tested for about 45 years, with the latest meta-analyses of randomised controlled trials (RCT) showing small/medium effects compared to non-active controls only. Three small studies piloted neurofeedback of frontal activations in ADHD using functional magnetic resonance imaging or near-infrared spectroscopy, finding no superior effects over control conditions. Brain stimulation has been applied to ADHD using mostly repetitive transcranial magnetic and direct current stimulation (rTMS/tDCS). rTMS has shown mostly negative findings on improving cognition or symptoms. Meta-analyses of tDCS studies targeting mostly the dorsolateral prefrontal cortex show small effects on cognitive improvements with only two out of three studies showing clinical improvements. Trigeminal nerve stimulation has been shown to improve ADHD symptoms with medium effect in one RCT. Modern neurotherapeutics are attractive due to their relative safety and potential neuroplastic effects. However, they need to be thoroughly tested for clinical and cognitive efficacy across settings and beyond core symptoms and for their potential for individualised treatment.

Ethical and Legal Considerations of Alternative Neurotherapies

Neurotherapies for diagnostics and treatment-such as electroencephalography (EEG) neurofeedback, single-photon emission computerized tomography (SPECT) imaging for neuropsychiatric evaluation, and off-label/experimental uses of brain stimulation-are continuously being offered to the public outside mainstream healthcare settings. Because these neurotherapies share many key features of complementary and alternative medicine (CAM) techniques-and meet the definition of CAM as set out in Kaptchuk and Eisenberg-here we refer to them as "alternative neurotherapies." By explicitly linking these alternative neurotherapy practices under a common conceptual framework, this paper draws attention to, and critically considers, the cross-cutting ethical and legal issues related to the provision of these services. The first section of this paper provides an updated empirical overview of uses of SPECT neuropsychiatric evaluations, EEG neurofeedback, and experimental/off-label forms of brain stimulation. Next, drawing on CAM bioethics scholarship, we highlight the pertinent ethical issues in the alternative neurotherapy context, including the truthful representation of evidence base, marketing to vulnerable populations, potential harms, provider competency, and conflicts of interest. Finally, we consider the principal legal issues at stake for the provision of alternative neurotherapies in the U.S., namely those related to licensing and scope-of-practice considerations. We conclude with recommendations for future research in this domain.

The Influence of Physiological and Psychological Learning Mechanisms in Neurofeedback vs. Mental Imagery Against Binge Eating

In biofeedback research, the debate on physiological versus psychological learning has a long tradition and is still relevant today, regarding new developments of biofeedback for behavior modification. Analyzing the role of these learning mechanisms may help improving the protocols and answer the question, whether feedback of physiological functions is necessary to modify a target behavior. We explored the presence and impact of physiological (EEG changes) versus psychological learning (changes in somatic self-efficacy) in a recently developed EEG neurofeedback protocol for binge eating. The protocol targets a reduction of food-cue induced cortical arousal through regulation of EEG high beta activity. In an experimental study accompanying a randomized controlled trial, pre and post treatment EEG measurements were analyzed in a neurofeedback group (n = 18) and an active mental imagery control group without physiological feedback (n = 18). Physiological learning in terms of EEG high beta reduction only occurred in the neurofeedback group. Post treatment, participants with successfully reduced binge eating episodes (≥ 50% reduction) showed lower EEG high beta activity than unsuccessful participants (p = .02) after neurofeedback, but not after mental imagery. Further, lower EEG high beta activity at post-treatment predicted fewer binge eating episodes in neurofeedback only. In mental imagery, somatic self-efficacy predicted treatment success instead of EEG activity. Altogether, the results indicate that physiological changes serve as a specific treatment mechanism in neurofeedback against binge eating. Reducing cortical arousal may improve eating behaviors and corresponding neurofeedback techniques should therefore be considered in future treatments.

Neurofeedback for Pain Management: A Systematic Review

Background: Chronic pain is a significant global health issue. For most individuals with chronic pain, biomedical treatments do not provide adequate relief. Given the evidence that neurophysiological abnormalities are associated with pain, it is reasonable to consider treatments that target these factors, such as neurofeedback (NF). The primary objectives of this review were to summarize the current state of knowledge regarding: (1) the different types of NF and NF protocols that have been evaluated for pain management; (2) the evidence supporting each NF type and protocol; (3) if targeted brain activity changes occur with NF training; and (4) if such brain activity change is associated with improvements on treatment outcomes. Methods: Inclusion criteria were intentionally broad to encompass every empirical study using NF in relation to pain. We considered all kinds of NF, including both electroencephalogram- (EEG-) and functional magnetic resonance imagining- (fMRI-) based. We searched the following databases from inception through September 2019: Pubmed, Ovid, Embase, Web of Science, PsycINFO. The search strategy consisted of a combination of key terms referring to all NF types and pain conditions (e.g., neurofeedback, rt-fMRI-NF, BOLD, pain, migraine). Results: A total of 6,552 citations were retrieved; 24 of these that were included in the review. Most of the studies were of moderate quality, included a control condition and but did not include a follow-up. They focused on studying pain intensity (83%), pain frequency, and other variables (fatigue, sleep, depression) in samples of adults (n = 7-71) with headaches, fibromyalgia and other pain conditions. Most studies (79%) used EEG-based NF. A wide variety of NF types and protocols have been used for pain management aiming to either increase, decrease or regulate brain activity in certain areas theoretically associated with pain. Conclusions: Given the generally positive results in the studies reviewed, the findings indicate that NF procedures have the potential for reducing pain and improving other related outcomes in individuals with chronic pain. However, the current evidence does not provide definitive conclusions or allow for reliable recommendations on which protocols or methods of administration may be the most effective. These findings support the need for continued - but higher quality - research in this area.

Towards a Pragmatic Approach to a Psychophysiological Unit of Analysis for Mental and Brain Disorders: An EEG-Copeia for Neurofeedback

This article proposes what we call an "EEG-Copeia" for neurofeedback, like the "Pharmacopeia" for psychopharmacology. This paper proposes to define an "EEG-Copeia" as an organized list of scientifically validated EEG markers, characterized by a specific association with an identified cognitive process, that define a psychophysiological unit of analysis useful for mental or brain disorder evaluation and treatment. A characteristic of EEG neurofeedback for mental and brain disorders is that it targets a EEG markers related to a supposed cognitive process, whereas conventional treatments target clinical manifestations. This could explain why EEG neurofeedback studies encounter difficulty in achieving reproducibility and validation. The present paper suggests that a first step to optimize EEG neurofeedback protocols and future research is to target a valid EEG marker. The specificity of the cognitive skills trained and learned during real time feedback of the EEG marker could be enhanced and both the reliability of neurofeedback training and the therapeutic impact optimized. However, several of the most well-known EEG markers have seldom been applied for neurofeedback. Moreover, we lack a reliable and valid EEG targets library for further RCT to evaluate the efficacy of neurofeedback in mental and brain disorders. With the present manuscript, our aim is to foster dialogues between cognitive neuroscience and EEG neurofeedback according to a psychophysiological perspective. The primary objective of this review was to identify the most robust EEG target. EEG markers linked with one or several clearly identified cognitive-related processes will be identified. The secondary objective was to organize these EEG markers and related cognitive process in a psychophysiological unit of analysis matrix inspired by the Research Domain Criteria (RDoC) project.

Consensus on the reporting and experimental design of clinical and cognitive-behavioural neurofeedback studies (CRED-nf checklist)

Neurofeedback has begun to attract the attention and scrutiny of the scientific and medical mainstream. Here, neurofeedback researchers present a consensus-derived checklist that aims to improve the reporting and experimental design standards in the field.

Neuroenhancement for sale: assessing the website claims of neurofeedback providers in the United States

Although electroencephalographic (EEG) neurofeedback is a technique that has been in existence for many decades, it has remained controversial, largely due to questions about efficacy. Yet neurofeedback is being widely offered to the public, often at great expense. To date, however, there has not been empirical data on which providers are utilizing neurofeedback, what they are offering it for, and how they are advertising the technique. The present study aimed to fill that gap by systematically analyzing the websites of neurofeedback practitioners in the United States. To that end, we obtained data from four directories of neurofeedback providers, extracting practitioner names, geographical locations, professional training, and website URLs. Only websites offering neurofeedback services (N=371) were included in the next step, wherein two coders independently coded the websites based on a codebook developed from preliminary analyses. We found that nearly all websites (97.0%) contained claims about at least one clinical indication, most commonly anxiety, ADHD/ADD, and depression; however, only 36.0% of providers had either a medical degree (MD) or a doctoral-level degree in psychology. The majority of websites advertised neurofeedback for cognitive (90.0%) or performance (67.9%) enhancement, and roughly three-quarters utilized language related to complementary and alternative medicine (CAM). In sum, there is a considerable divergence between the scientific literature on neurofeedback and the marketing of neurofeedback services to the general public, raising concerns regarding the misrepresentation of services and misleading advertising claims.

Effects of a Vibro-Tactile P300 Based Brain-Computer Interface on the Coma Recovery Scale-Revised in Patients With Disorders of Consciousness

Persons diagnosed with disorders of consciousness (DOC) typically suffer from motor and cognitive disabilities. Recent research has shown that non-invasive brain-computer interface (BCI) technology could help assess these patients' cognitive functions and command following abilities. 20 DOC patients participated in the study and performed 10 vibro-tactile P300 BCI sessions over 10 days with 8-12 runs each day. Vibrotactile tactors were placed on the each patient's left and right wrists and one foot. Patients were instructed, via earbuds, to concentrate and silently count vibrotactile pulses on either their left or right wrist that presented a target stimulus and to ignore the others. Changes of the BCI classification accuracy were investigated over the 10 days. In addition, the Coma Recovery Scale-Revised (CRS-R) score was measured before and after the 10 vibro-tactile P300 sessions. In the first run, 10 patients had a classification accuracy above chance level (>12.5%). In the best run, every patient reached an accuracy ≥60%. The grand average accuracy in the first session for all patients was 40%. In the best session, the grand average accuracy was 88% and the median accuracy across all sessions was 21%. The CRS-R scores compared before and after 10 VT3 sessions for all 20 patients, are showing significant improvement (p = 0.024). Twelve of the twenty patients showed an improvement of 1 to 7 points in the CRS-R score after the VT3 BCI sessions (mean: 2.6). Six patients did not show a change of the CRS-R and two patients showed a decline in the score by 1 point. Every patient achieved at least 60% accuracy at least once, which indicates successful command following. This shows the importance of repeated measures when DOC patients are assessed. The improvement of the CRS-R score after the 10 VT3 sessions is an important issue for future experiments to test the possible therapeutic applications of vibro-tactile and related BCIs with a larger patient group.

The efficacy of biofeedback for the treatment of insomnia: a critical review

BACKGROUND

The popularity of biofeedback as a non-pharmacological treatment option for insomnia has increased in recent times despite inconsistent empirical evidence for its therapeutic efficacy.

OBJECTIVE

The purpose of the current review was to systematically assess the efficacy of using biofeedback to treat insomnia.

METHODS AND RESULTS

A search of electronic databases (PubMED, MEDLINE, OvidSP, Ovid EMBASE, PsychInfo, The Cochrane Library including Cochrane Reviews), clinical trials databases and registries (Clinical Trials Database [US], Australian New Zealand Clinical Trials Registry [ANZCTR]) and online journal (eg, SLEEP, Sleep Medicine) identified 92 studies. Of these, 50 publications were descriptive or review papers about use of biofeedback for the treatment of insomnia, while an additional 37 did not meet the detailed inclusion criteria (ie not original research, participants do not meet the diagnostic criteria for insomnia). Six full-text articles met inclusion criteria and were included in this review. Methodological flaws including poor study design (small sample size, lack of control group) limit the validity of the body of work in this field to date and fail adequately to account for other unspecified factors likely to drive the observed changes, such as care and attention of those administering the treatment, as well as the expectations and motivations of the patient.

CONCLUSION

There is an urgent need for future studies to clarify the role of unspecific placebo effects when reporting biofeedback effects for the treatment of insomnia.