The effort to make brain stimulation faster without sacrificing clinical benefit is becoming a major focus of interventional psychiatry research. A new systematic review and dose-response meta-analysis suggests that accelerated iTBS for depression may provide meaningful antidepressant effects while revealing that how stimulation is delivered could be just as important as how quickly treatment is completed.
Published online in Brain Stimulation in July 2026, the analysis evaluated randomized controlled trials of accelerated intermittent theta-burst stimulation, or aiTBS, for major depressive episodes. The findings provide a more detailed picture of how treatment dose, session spacing, and targeting strategy may influence outcomes.
Why Faster TMS Has Become A Priority
Repetitive transcranial magnetic stimulation has become an established noninvasive intervention for major depressive episodes, but traditional treatment courses can require daily visits for four to six weeks. Intermittent theta-burst stimulation substantially shortens each individual treatment session, yet standard iTBS is still typically delivered once daily across several weeks.
Accelerated protocols attempt to compress that schedule by delivering multiple iTBS sessions each day. This approach could reduce the overall treatment window and potentially make neuromodulation more practical in clinical settings where shorter treatment courses are valuable.
The challenge is that accelerated protocols have varied considerably. Studies have used different numbers of daily sessions, total stimulation pulses, intervals between sessions, and methods for identifying the brain region to stimulate.
Accelerated iTBS For Depression Shows A Meaningful Clinical Signal
Researchers analyzed 15 randomized controlled trials involving 704 participants experiencing either unipolar or bipolar depressive episodes. Across the studies, active accelerated iTBS produced significantly greater improvement in depressive symptoms than the comparison conditions, with a standardized effect size of 0.69.
Clinical response was observed in 43.53% of participants receiving active stimulation compared with 19.66% in the comparison groups. The calculated number needed to treat for response was five. Remission also favored active stimulation, occurring in 28.03% of participants compared with 13.92% in the comparison groups, with a number needed of 10 to treat.
Treatment discontinuation was also comparable between groups. This finding suggests that accelerated treatment schedules were generally acceptable to participants in the trials analyzed.
Dose And Timing May Matter More Than Speed Alone
One of the most clinically relevant findings involved treatment intensity and the amount of time between stimulation sessions.
Researchers identified nonlinear relationships between improvement in depressive symptoms and both the total number of pulses and the total number of treatment sessions. Intersession timing was particularly notable. Protocols using intervals of at least 30 minutes demonstrated substantially larger effects than protocols using shorter intervals.
This observation may relate to metaplasticity, the process through which previous neural activity influences the brain’s response to subsequent stimulation. Rather than simply delivering as many sessions as possible in a short period, allowing sufficient time between sessions could influence how repeated stimulation affects neural circuits.
The researchers caution, however, that these treatment variables are difficult to separate. High-dose protocols frequently used longer intervals alongside more sophisticated targeting methods.
Connectivity-Guided Targeting Could Add Another Layer Of Precision
Another important finding involved where stimulation was delivered.
Trials using functional connectivity-based neuronavigation demonstrated substantially larger pooled effects than studies using structural or atlas-based navigation or non-neuronavigated targeting. Functional targeting attempts to identify a dorsolateral prefrontal cortex location according to its relationship with depression-relevant brain networks.
This approach represents a broader shift in TMS research. Instead of selecting approximately the same anatomical location for every patient, connectivity-guided methods aim to identify stimulation sites according to the organization of functional brain circuits.
However, the findings do not establish that connectivity-guided targeting alone produces better outcomes. Studies using this method also tended to employ higher stimulation doses and longer intervals between sessions. The independent contributions of targeting, dose, and timing therefore remain difficult to determine.
It’s also important to note that some of the accelerated protocols included in the analysis evaluated proprietary technologies. For example, several studies assessed BrainsWay’s accelerated H1 Deep TMS protocol (SWIFT), which uses the company’s H1 coil and treatment approach. While these trials contribute to the overall evidence supporting accelerated TMS, the findings of this meta-analysis should not be interpreted as evidence for any single device or protocol.
What This Could Mean For Clinical TMS
The study suggests that the future of accelerated TMS may depend on protocol optimization rather than simply delivering conventional stimulation faster.
Dose, total treatment sessions, intersession spacing, and individualized targeting may work together to influence clinical outcomes. This distinction could become increasingly important as researchers determine how accelerated protocols might move from specialized research programs into broader psychiatric practice.
Important questions remain. The combined sample across the 15 trials was relatively modest, stimulation protocols varied substantially, and long-term follow-up data were limited. The authors therefore emphasize the need for additional randomized studies that can more clearly separate the effects of stimulation dose, timing, and precision targeting.
Overall, the findings strengthen the evidence supporting accelerated iTBS as an effective approach for reducing depressive symptoms. Future research will need to determine which combination of stimulation intensity, session spacing, and individualized targeting can produce the most reliable and durable clinical benefits.
Citations
- Santos JM, Yamamoto BR, Damiano RF, et al. “Accelerated intermittent theta-burst stimulation for major depressive episodes: systematic review and dose-response meta-analysis.” Brain Stimulation. Published online July 27, 2026.
https://doi.org/10.1016/j.brs.2026.103174 - Cai DB, Qin ZJ, Lan XJ, et al. “Accelerated intermittent theta burst stimulation for major depressive disorder or bipolar depression: A systematic review and meta-analysis.” Asian Journal of Psychiatry. 2023 https://pubmed.ncbi.nlm.nih.gov/37201381/
Explore more at https://www.interventionalpsychiatry.org/
