Better than sham? A double-blind placebo-controlled neurofeedback study in primary insomnia

Abstract

See Thibault et al. (doi:10.1093/awx033) for a scientific commentary on this article.Neurofeedback training builds upon the simple concept of instrumental conditioning, i.e. behaviour that is rewarded is more likely to reoccur, an effect Thorndike referred to as the 'law of effect'. In the case of neurofeedback, information about specific electroencephalographic activity is fed back to the participant who is rewarded whenever the desired electroencephalography pattern is generated. If some kind of hyperarousal needs to be addressed, the neurofeedback community considers sensorimotor rhythm neurofeedback as the gold standard. Earlier treatment approaches using sensorimotor-rhythm neurofeedback indicated that training to increase 12-15 Hz sensorimotor rhythm over the sensorimotor cortex during wakefulness could reduce attention-deficit/hyperactivity disorder and epilepsy symptoms and even improve sleep quality by enhancing sleep spindle activity (lying in the same frequency range). In the present study we sought to critically test whether earlier findings on the positive effect of sensorimotor rhythm neurofeedback on sleep quality and memory could also be replicated in a double-blind placebo-controlled study on 25 patients with insomnia. Patients spent nine polysomnography nights and 12 sessions of neurofeedback and 12 sessions of placebo-feedback training (sham) in our laboratory. Crucially, we found both neurofeedback and placebo feedback to be equally effective as reflected in subjective measures of sleep complaints suggesting that the observed improvements were due to unspecific factors such as experiencing trust and receiving care and empathy from experimenters. In addition, these improvements were not reflected in objective electroencephalographic-derived measures of sleep quality. Furthermore, objective electroencephalographic measures that potentially reflected mechanisms underlying the efficacy of neurofeedback such as spectral electroencephalographic measures and sleep spindle parameters remained unchanged following 12 training sessions. A stratification into 'true' insomnia patients and 'insomnia misperceivers' (subjective, but no objective sleep problems) did not alter the results. Based on this comprehensive and well-controlled study, we conclude that for the treatment of primary insomnia, neurofeedback does not have a specific efficacy beyond unspecific placebo effects. Importantly, we do not find an advantage of neurofeedback over placebo feedback, therefore it cannot be recommended as an alternative to cognitive behavioural therapy for insomnia, the current (non-pharmacological) standard-of-care treatment. In addition, our study may foster a critical discussion that generally questions the effectiveness of neurofeedback, and emphasizes the importance of demonstrating neurofeedback efficacy in other study samples and disorders using truly placebo and double-blind controlled trials.

Keywords: SMR; insomnia; neurofeedback; neurotherapy; placebo.

Figure 1

Study design. After participants had undergone an eligibility assessment (via email and phone) they came to the laboratory for a screening night to exclude sleep disorders besides insomnia. Then subjects completed four visits each, each one comprising two experimental nights with polysomnography (either preceded by a declarative or procedural learning task). In between Visits 1 and 2, and 3 and 4 all patients (patients with insomnia, misperception insomniacs) completed 12 sessions of NFT and PFT. Between Visits 2 and 3, a 3-month washout period was introduced and a final follow-up after 3 months was conducted. The order of NFT and PFT was counterbalanced (half of the patients receiving NFT first, and half of the patients receiving PFT first) and the protocol was kept double-blind until study completion.

Figure 2

Effects of NFT/PFT training on SMR band power during training. Note that as a group all patients [patients with insomnia (INs), misperception insomniacs (MPs)] were able to significantly increase power in the SMR frequency band during NFT (as compared to PFT). A group of young healthy neurofeedback controls (NC) is plotted for comparison. Note that the x-axis informs about the rewarded frequency bands for PFT and NFT. Training sessions 2 and 12 are not displayed due to technical problems.

Figure 3

Short-term effects in the SMR band. A resting EEG (with eyes open) was recorded directly before and after each PFT and NFT training block. Analyses revealed that even directly following training, patients with insomnia and misperception insomniacs (here pooled) had SMR amplitude values (on the trained site C3) that did not differ from the values preceding the training blocks. Note that amplitude is normalized to the individual total-amplitude (1–30 Hz) to account for unspecific differences between participants.

Figure 4

Long-term effects of NFT/PFT training on sleep spindle activity and sleep spindle density. The graphs on the left illustrate the slow (11–13 Hz) and fast (13–15 Hz) sleep spindle activity (mean spindle amplitude × duration) for the NFT and PFT conditions. The graphs on the right illustrate sleep spindle density (number of spindles / min). All spindle detections have been performed on (trained) electrode C3 and in N2 sleep where spindles are most prevalent. Pre and post refer to the mean of two full polysomnography nights before or after 12 sessions of NFT/PFT. Error bars indicate ± 1 standard error of the mean (SEM).

Figure 5

Long-term effects of NFT/PFT training on subjective sleep quality (PSQI). The figure depicts the subjective changes in sleep quality as evaluated with the PSQI. Participants completed the questionnaire before and after the 12 NFT and PFT sessions, as well as 3 months thereafter (i.e. follow-up). Note a general decrease of sleep complaints from pre- to post-training independent from NFT/PFT and a tendency to further decrease to the follow-up. A PSQI total score > 5 is indicative of poor sleep (marked with the dashed line). Error bars indicate ± 1 SEM. IN = patients with insomnia; MP = misperception insomniacs.