| Paper authors: | Lorina Zapf, Tyler S. Kaster, Fidel Vila-Rodriguez, Zafiris J. Daskalakis, Jonathan Downar, Daniel M. Blumberger |
| Year of paper publication: | 2025 |
| Post authors: | Caleb Pozdnikoff, Sarah Kesler, Fidel Vila-Rodriguez |
| Check out the full research article: | Zapf et al. (2025) The effect of once-daily vs. twice-daily intermittent theta burst stimulation on suicidal ideation in treatment-resistant depression |
Introduction
Repetitive transcranial magnetic stimulation (rTMS) has long been used to treat treatment-resistant depression. A newer, shorter version of rTMS called intermittent theta burst stimulation (iTBS) has shown potential in reducing suicidal ideation in people with depression. Would iTBS be more effective in reducing suicidal ideation if given twice-daily instead of only once?
This analysis used data from a large clinical trial to investigate whether receiving iTBS twice-daily would be more effective in reducing suicidal ideation than giving it once-daily in patients with treatment-resistant depression.
Methods
The researchers used data from a previous study called the CARTBIND trial (see our previous infographic on this trial here). In this trial, researchers recruited patients with treatment-resistant depression and compared receiving iTBS once-daily versus iTBS twice-daily. In both groups, patients received 1,200 TMS pulses. In the once-daily group this was all in the first session, while in the twice-daily group patients received 600 pulses in the first session, and 600 pulses in the second. In this analysis, they only used data from people who had suicidal ideation at the start of the trial. This resulted in 158 people being included in this analysis.
The researchers gathered the participant’s answers from 4 different questionnaires that included questions about suicidality and averaged these scores. The suicidality results from before and after treatment were then compared between the once-daily and twice-daily groups.
Results
- Both groups showed a meaningful reduction in suicidal ideation.
- However, the twice-daily iTBS group did not show a significantly lower reduction in symptoms than the once-daily group.
- This means that twice daily iTBS did not decrease suicidal ideation more than once daily iTBS.
- Improvements in suicidal ideation were closely linked to improvements in perceived quality of life and the ability to feel pleasure (anhedonia).
Conclusion
The study found no significant difference in outcomes between the twice-daily iTBS and the once-daily iTBS groups. However, both the once-daily and twice-daily schedules lead to meaningful reductions in suicidal ideation for many people. These improvements in suicidal thoughts were also strongly connected to better quality of life and a renewed ability to feel pleasure, suggesting these factors are key targets for treatment. Since doubling the daily sessions did not accelerate or improve recovery, finding a more optimal iTBS treatment protocol remains a priority for future research.