Factors influencing therapeutic effectiveness of electroencephalogram-based neurofeedback against core symptoms of ADHD: a systematic review and meta-analysis

Background: Factors affecting the effectiveness of electroencephalogram-based neurofeedback (EEG-NF) against the core symptoms of attention-deficit/hyperactivity disorder (ADHD) remain unclear. Methods: We searched the PubMed, Embase, Web of Science, ClinicalKey, Cochrane CENTRAL, ScienceDirect, and databases from inception to August 2022 for randomized controlled trials (RCTs) on patients with ADHD involving outcome assessments of improvements on behavioural rating scales of inattention, hyperactivity/impulsivity, and global symptoms. Comparators included nonactive (e.g., wait list/treatment as usual) and active (e.g., cognitive training) controls. Results: Our analyses included 21 RCTs comprising 1261 participants. Our results demonstrated significantly better improvement in symptoms of inattention, hyperactivity/impulsivity and global symptoms of ADHD associated with EEG-NF than comparators from both proximal (p = 0.01, p = 0.02 and p = 0.01, respectively; e.g., parents) and distal (p = 0.01, p < 0.05 and p = 0.01; e.g., teachers) raters. Meta-regression revealed a positive association between therapeutic effects of EEG-NF and intelligence quotient (IQ) from observations of the most proximal raters. Subgroup analysis for studies combining 2 EEG-NF protocols showed better therapeutic effectiveness against symptoms of ADHD than those using a single NF protocol, whereas subgroup analysis adopting a double-blind design failed to demonstrate superiority of EEG-NF to sham control. Moreover, therapeutic effectiveness of EEG-NF was significantly better when wait list/treatment as usual comparators were used compared with sham/placebo EEG-NF controls on subgroup analysis.Limitations:Our findings are limited by the lack of a double-blind design in most of the studies included in our analyses. Conclusion: Our results support the effectiveness of EEG-NF for improving inattention, hyperactivity/impulsivity, and global symptoms in patients with ADHD. The high risk of detection and performance bias warrants further study.