The dos and don’ts of neurofeedback: a review of controlled studies in healthy adults
Front. Hum. Neurosci., 17 June 2016
The Do’s and Don’ts of Neurofeedback Training:A Review of the Controlled Studies Using Healthy Adults
Jacek Rogala, Katarzyna Jurewicz, Katarzyna Paluch, Ewa Kublik, Ryszard Cetnarski and Andrzej Wróbel
The purpose of neurofeedback treatment is to cause changes in the power of the desired frequency bands to bring about beneficial changes in behavior or motor function. The effectiveness of different protocols can be measured using two independent variables:
- Changes in brain wave activity
- Behavioral changes in the desired cognitive function (for therapeutic applications, the changes must be stable).
To establish a strong relationship between these variables and the selected protocols, similar variations should not be included when appropriate control samples have been used. The main objective of this review is to evaluate the evidence reported in the scientific literature supporting the validity of different protocols. The main concern is highlighting the role of non-specific and uncontrolled factors that can contribute to the results of such studies.
Non-specific factors are usually neglected in study design or information is not available, which means that conclusions should be interpreted with caution. As an output of this review, a list of dos and don’ts based on small experimental samples with appropriate control groups not accounting for effects unrelated to neurofeedback is provided that can be used in future methodology development.
Two features that have been positively related to the expected changes in the power of frequency bands have been obtained:
- Protocols that focus on working on a smaller number of frequency bands.
- More electrodes have been used for neurofeedback.
However, no evidence was found in support of a positive relationship between neurofeedback frequency band power changes and specific behavioral effects.
The goal of EEG neurofeedback (EEG-NFB) training is to induce changes in the power of targeted EEG bands to produce beneficial changes in cognitive or motor function. The effectiveness of different EEG-NFB protocols can be measured using two dependent variables: (1) changes in EEG activity and (2) behavioral changes of a targeted function (for therapeutic applications the desired changes should be long-lasting). To firmly establish a causal link between these variables and the selected protocol, similar changes should not be observed when appropriate control paradigms are used. The main objective of this review is to evaluate the evidence, reported in the scientific literature, which supports the validity of various EEG-NFB protocols. Our primary concern is to highlight the role that uncontrolled nonspecific factors can play in the results generated from EEG-NFB studies. Nonspecific factors are often ignored in EEG-NFB designs or the data are not presented, which means conclusions should be interpreted cautiously. As an outcome of this review we present a do’s and don’ts list, which can be used to develop future EEG-NFB methodologies, based on the small set of experiments in which the proper control groups have excluded non-EEG-NFB related effects. We found two features which positively correlated with the expected changes in power of the trained EEG band(s): (1) protocols which focused on training a smaller number of frequency bands and (2) a bigger number of electrodes used for neurofeedback training. However, we did not find evidence in support of the positive relationship between power changes of a trained frequency band(s) and specific behavioral effects.