What Does Science Say About Neurofeedback?
Updated: Feb 25, 2021
We've done the work and looked over hundreds of neurofeedback studies for you, categorizing them based on different brain use cases (peak performance, ADHD, anxiety, depression, PTSD, and more...).
In this article, you can find research summaries. A PDF containing the summaries and a categorized reference lists is embedded at the end of the article (or here).
Below are summaries of the current research related to EEG neurofeedback, including protocols used, findings and more, in seven major areas of brain health: ADHD, Peak Performance, Anxiety, PTSD, Addictive Disorders, Cognitive Decline, and Depression.
Attention-Deficit Hyperactivity Disorder (ADHD)
ADHD is the most well-studied condition in neurofeedback research. Based on meta-analyses and large multicenter randomized controlled trials (RCTs), two frequency neurofeedback protocols researched for more than 40 years have been shown efficacious and specific for ADHD: theta-beta ratio (TBR) and sensorimotor rhythm (SMR) (AAPB Guidelines; La Vaque et al., 2002). Frequency neurofeedback for ADHD received a grade 1 (‘‘best support’’) rating from the American Academy of Pediatrics in 2013.
TBR aims to decrease theta (4–7 Hz) and/or increase beta (12–21 Hz) power in central and frontal locations to reduce the high theta-beta ratios, high theta power, and/or low beta power characteristic of children and adults with ADHD.
Recent RCTs suggest that 30–40 sessions of TBR neurofeedback were as effective as methylphenidate in ameliorating inattentive and hyperactivity symptoms and were even associated with superior post-treatment academic performance (Duric et al., 2012; Meisel et al., 2013).
SMR over the sensorimotor strip (predominantly right-central) is based on the functional association of the sensorimotor rhythm with behavioral inhibition in ADHD. In seminal studies (Lubar & Shouse, 1976; Shouse & Lubar, 1979), it was demonstrated that the beneficial hyperactivity-reducing effects of combined SMR/theta training were maintained even after psychostimulants were withdrawn in hyperactive children. Studies suggest that TBR and SMR reduce inattentive and hyperactive/impulsive symptoms to a similar extent and after a comparable number of training sessions.
A series of meta-analyses have shown that the standard TBR and SMR protocols improve ADHD symptoms, especially inattention (Arns et al., 2009; Micolaud-Franchi et al., 2014; Bussalb et al., 2019; Riesco-Matías et al., 2019). Efficacy is clear for parentally-rated symptoms and less certain for teacher-rated symptoms (Micolaud-Franchi et al., 2014; Cortese et al., 2016; Razoki, 2018; Bussalb et al. 2019). However, parent ratings are associated with candidate gene pathways (Bralten et al., 2013), and teachers may be less sensitive to change (Cortese et al., 2016; Bussalb et al., 2019).
Using objective cognitive outcomes, a recent meta-analysis found neurofeedback to be more efficacious than cognitive training in ameliorating symptoms of inhibition (Lambez et al., 2020). Critically, a meta-analysis focusing on long-term maintenance found that after an average 6 months from completion of neurofeedback, the beneficial effects of neurofeedback were superior to semi-active control groups and methylphenidate (Van Doren et al., 2019). These findings demonstrate that whereas medication efficacy diminishes over time, neurofeedback efficacy increases.
The best evidence for efficacy comes from double-blind placebo-controlled RCTs, though it is challenging to devise a placebo condition that properly controls for psychosocial factors like perceptibility and motivation (Gaume et al., 2016). One of the largest and most comprehensive such trials is currently being carried out (International Collaborative ADHD Neurofeedback; ICAN; Arnold et al., 2013; 2018; 2019), with conclusive results anticipated soon.
EEG neurofeedback for ‘peak’ or ‘optimal’ performance focuses on facilitating brain performance in healthy individuals to achieve maximal brain functioning. Specifically, peak performance protocols aim to control level of arousal, attention and motivation, optimizing level of autonomic control and ability to shift states. A concrete goal of peak performance training is the completion of a specific function or task with fewer errors and greater efficiency, resulting in a more positive outcome (Vernon, 2005).
Twenty-three controlled studies have reported neurofeedback learning indices along with beneficial outcomes, including gains in: sustained attention, orienting and executive attention, the P300b event-related potential, memory, spatial rotation, reaction time, complex psychomotor skills, implicit procedural memory, recognition memory, perceptual binding, intelligence, mood and well-being (Gruzelier et al., 2014). Gains have been achieved by a variety of neurofeedback protocols, including: sensorimotor rhythm (SMR), beta and gamma, theta, and alpha power. Indeed peak performance surpasses other neurofeedback domains in that the majority of studies demonstrate evidence of learning.
Neurofeedback may optimize cognitive processing and learning by modifying white matter pathways and gray matter volume resulting in faster conduction velocity in neural networks. With regard to alpha power training, it has been suggested that engaging in a well-practiced task is associated with elevated alpha power, reflecting decreased cortical information processing and a more automatic stage of skill acquisition (Mirifar et al., 2017). In one study, increased SMR power improved accuracy and speed of surgery skills (Ros et al., 2009). In another study, inhibition of theta power reduced radar detection errors (Beatty et al., 1974).
Egner and Gruzelier (2004) reported faster reaction time in an attention task following an inhibit theta/enhance mid-beta protocol, and memory improvement has been reported following upper-alpha training (Escolano et al., 2011; Zoefel et al., 2011). A recent review found that 12 of 14 full studies reported positive effects in athletes, with 7 of 10 showing positive effects on performance, 3 of 6 studies reporting improved affective outcomes, and 3 of 3 reporting better cognitive outcomes (Mirifar et al., 2017). Though the evidence is overwhelmingly encouraging, sample sizes are small, and little is known about how methodological characteristics (e.g., number of training sessions, particular neurofeedback protocol) impact outcomes (Vernon et al., 2009; Mirifar et al., 2017). Thus larger, controlled studies are needed to address these issues and provide a clear understanding of the specific effects of neurofeedback on peak performance.
Alpha-theta (alpha, theta, alpha-theta enhancement) neurofeedback training, which reduces arousal, has been applied to reduce anxiety (as well as addiction) and create a generally relaxed state of well-being (Moore, 2000; Gruzelier, 2009). EEG neurofeedback offers an attractive option, as medication is only mildly more effective than placebo in treating anxiety disorders. Training is typically administered with eyes closed while listening to auditory feedback for a total of 7-12 hours of training.
As applied to generalized anxiety disorder (GAD), 9 of 10 neurofeedback studies reviewed by Moore (2000) and Hammond (2005a,b) produced positive changes in clinical outcome, with evidence for an anxiety reduction that endures even after 18 months (Watson et al., 1978). Indeed, for anxiety disorders, neurofeedback qualifies for the evidence-based designation of an efficacious treatment (Hammond, 2005a,b), with GAD and phobic anxiety disorder (as well as PTSD, summarized separately), demonstrating effects beyond placebo and meeting criteria for “probably efficacious” on the basis of American Psychological Association Clinical Psychology Division (Chambless & Hollon, 1998) and biofeedback specialty criteria (La Vaque et al., 2002). A recent systematic review of biofeedback in anxiety disorders (Tolin et al., 2020) reported a large advantage for EEG neurofeedback over wait list control groups, with higher quality studies showing superior effects; there was no clear benefit relative to active control groups, though few such studies were available to be included.
In a GAD study of high-talent musicians performing under stressful conditions, only musicians who received alpha-theta (enhancement) training yielded enhanced musical performance under stress (Egner & Gruzelier, 2003). In one RCT of test anxiety, neurofeedback participants generated 33% more alpha and showed a significant reduction in anxiety; by comparison, untreated participants and those receiving relaxation training experienced no significant symptom reduction (Garrett & Silver, 1976). A recent study in adolescents with self-reported attention and anxiety (e.g., thoughts of worry) symptoms found enhanced alpha and sensorimotor rhythm (SMR) along with improved symptoms (by visual analogue scales) after neurofeedback training of alpha, theta, and SMR twice a week for five weeks (Tsatali et al., 2019).
Post-Traumatic Stress Disorder (PTSD)
Evidence-based practice guidelines for PTSD recommend trauma-focused cognitive behavioral therapy (CBT) and eye movement desensitization and reprocessing (EMDR) as effective treatment modalities. However, the dropout rate for these therapies is high (Bisson et al., 2013; National Institute of Clinical Excellence (NICE), 2005). Pharmacological treatment (e.g., selective serotonin reuptake inhibitors; SSRIs) may also be effective, but the evidence is weaker. Further, treatment with pharmacological and psychotherapy-based therapies may last several years and are ineffectual for ~40% of patients (Bradley et al., 2005; NICE, 2005; Stein et al., 2006).
EEG neurofeedback is a non-pharmacologic alternative that meets “probably efficacious” criteria for PTSD (Hammond, 2005a,b; Reiter et al., 2016) on the basis of American Psychological Association Clinical Psychology Division (Chambless & Hollon, 1998) and biofeedback specialty criteria (La Vaque et al., 2002). A recent systematic review and meta-analysis pooled data across four randomized controlled trials (RCTs) in PTSD (n=123) and revealed a very large effect size (standard mean difference of -2.30; 95% CI: -4.37 to -0.24) for improvement in PTSD symptoms that exceeded effect sizes for internet-based cognitive therapy and meditation-related exercises (Steingrimsson et al., 2020). The studies consistently favored neurofeedback in terms of symptom severity and number of patients achieving remission. Specifically, PTSD symptoms were reduced by 34-66% in the neurofeedback group, but ranged from a reduction of 15% to an increase of 13% in the control groups (3 passive, 1 active). The one study with follow-up (van der Kolk et al., 2016) reported 46% symptom reduction posttreatment and 51% symptom reduction at 1-month follow-up (compared with reductions of 13% posttreatment and 14% at 1-month follow-up in controls). At 1-month follow-up, 58% (11/19) of neurofeedback patients achieved remission as compared with 11% (2/19) of controls. In one study (Noohi et al., 2017), neurofeedback significantly improved performance on cognitive tests of executive function. In another (Peniston & Kulkosky, 1991), all neurofeedback patients (14/14) reduced psychotropic medication use as compared with one patient (1/13) in the control group.
Though the extant evidence is encouraging (see also reviews by Reiter et al. 2016; Panisch & Hai, 2018), additional controlled studies are desirable for greater confidence and clarity regarding the efficacy of neurofeedback in PTSD. Indeed small, heterogene