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A randomised controlled trial published in The BMJ looks at accelerated continuous theta burst stimulation (a-cTBS) targeting left primary motor cortex for children with autism spectrum disorder.
Prof Dorothy Bishop, Professor of Developmental Neuropsychology, University of Oxford, said:
“This looks like a well-powered and well-conducted randomized controlled trial, but I do have misgivings about it for two reasons.
“First, I think the study is ethically questionable. Brain stimulation (or sham stimulation in controls) was applied to the left motor cortex of autistic children aged 4 to 10 years.
“We are told: “Stimulation sessions were performed hourly, with 10 sessions per day (18,000 pulses per day) over five consecutive days”. This sounds like a taxing schedule for anyone, let alone young autistic children, half of whom had intellectual disability. It sounds like they would have had to turn up at a clinic early in the morning and leave early evening for five consecutive days. Children with autism often find it difficult to face disruption to daily routines, and many have sensory sensitives.
“Second, the basis of the intervention seems implausible. Brain stimulation as an intervention has some credibility in cases where you are doing some kind of training in conjunction with the stimulation, where it may enhance neural circuits involved in learning. But that was not the case here. The outcome measure, the SRS-2, is really focused on habitual behaviour, asking parents to rate on a 4-point scale (from ‘not true’, to ‘always true’) items such as “is socially awkward” or “has difficulty relating to peers”, yet improvements were reported within 3 days of completing the intervention. There seems to be an implicit assumption that problems with social communication are caused by some deficit in brain activation, and can be reversed in a matter of days by stimulation – it is almost as if it is assumed that there is a “normal” child that can be released just by stimulating the brain. That seems a rather unrealistic assumption, given that children’s social behaviours develop over years.
Overall, I don’t think this is an intervention that would be feasible or desirable for many autistic children. I’d urge caution in acting on these results.“
Dr David McGonigle, Lecturer in the Schools of Psychology and Biosciences, Cardiff University, said:
“This trial provides evidence of statistically significant – but, importantly, rather modest and decidedly short-term improvements in social communication, with small effect sizes and a follow-up limited to one month. Any interpretation of the effects here is further constrained by the authors’ reliance on SRS-2 and the potential for expectancy effects in their study. In addition, while adverse events were mild, their higher frequency in the intervention group suggests tolerability should be interpreted cautiously, and, from my own experience, the choice of stimulation target – the motor cortex – also raises questions about mechanistic specificity. These findings are best interpreted as preliminary evidence of modest short-term effects, rather than support for clinical implementation at this stage. Finally, I am concerned about the use of brain stimulation in such a young population as we are still uncertain about its effect on the developing brain.”
Prof Roi Cohen Kadosh, Professor of Cognitive Neuroscience, and Head of School of Psychology, University of Surrey, said:
“This press release is broadly accurate and reflects a well-conducted, relatively large randomised controlled trial. The findings are encouraging and suggest that accelerated continuous theta burst stimulation, a rapid form of patterned magnetic brain stimulation delivered using TMS equipment, may improve social communication in a group of autistic children for one month after treatment.
“That said, the results should be interpreted with some caution. In this trial, the active stimulation group had a higher average SRS-2 score than the sham group at baseline (84.28 vs 78.85, so 5.43 points), meaning they started off with more severe difficulties on the primary outcome measure. This is worth noting because baseline differences between groups can sometimes partly contribute to the size of the improvement seen after treatment. The reported advantage of active stimulation over sham was a reduction of 6.25 points after treatment and 6.17 points at one-month follow-up. The authors acknowledged this limitation. The authors have addressed several potential confounders, including expectancy effects (which me and my group showing two years ago that can explain some of the TMS effects) and the statistical analyses are generally strong, but a longer follow-up is needed to determine whether the benefits are durable. But this is a very good and promising start. We cannot expect already at this stage to examine what will happen, for example, 6 months or 12 months later.
“It is also important not to overstate what this study shows. The work supports further investigation of this approach as a potential addition to existing support, and its strength is that it uses a biologically direct approach, which may offer an important complementary route. More mechanistic research is now needed to establish how the stimulation affects the brain, whether the motor cortex is the optimal target, and whether more personalised approaches could produce stronger and more reliable benefits.”
‘Accelerated continuous theta burst stimulation targeting left primary motor cortex for children with autism spectrum disorder: multicentre randomised sham-controlled trial’ by Hangyu Tan, et al. was published in The BMJ at 23:30 UK time Wednesday 29 April 2026.
DOI: http://dx.doi.org/10.1136/bmj-2025‑086295
Declared interests
Prof Dorothy Bishop: “None”
Dr David McGonigle: “no conflicts of interest to declare.”
Prof Roi Cohen Kadosh: “Aside from my academic post as the Head of School of Psychology and Professor of Cognitive Neuroscience, I am founder, director, and shareholder of Cognite Neurotechnology Ltd, a company developing neurotechnology. I have also been involved in developing tools relevant to research methodology in this area.”