Is Two Weeks of iTBS Enough?

The benefits are real by two weeks, but not sustainable

STUDY: Ørbo MC et al, JAMA Netw Open 2026

STUDY TYPE: Randomized, double-blind, sham-controlled trial

FUNDING: Northern Norway Regional Health Authority

Background

Intermittent theta-burst stimulation (iTBS) is a shortened form of transcranial magnetic stimulation, requiring sessions lasting 3 minutes/day instead of the usual 20-40 min. It is usually given over 4-6 weeks, and some recommend 8 weeks. This trial tested whether a two week course is sufficient.

The Study

• 73 adults with moderate to severe major depressive disorder, any level of treatment resistance.
• Randomized to two weeks of 10 weekday sessions of active iTBS or sham stimulation over the left dorsolateral prefrontal cortex.
• Assessed at day 5, day 10, and 4 weeks after the last session, using the clinician-rated MADRS and the self-report BDI-II.

Active iTBS beat sham on the MADRS by day 5 and the gap widened by day 10, when depression scores dropped 42% with iTBS versus 22% with sham (effect size = 0.61). The self-rated BDI-II did not show a significant difference. Response and remission rates on day 10 numerically favored iTBS (40% versus 23% response) but didn’t reach statistical significance.

By 4 weeks, the sham group had kept improving and caught up entirely. Neither the MADRS nor the BDI-II showed a group difference at follow-up.

Side Effects

Treatment was well tolerated. Scalp pain and tingling were more common with active stimulation.

Limitations

The trial fell short of its planned sample size due to recruitment problems, which likely hurt its ability to detect differences on secondary outcomes. Ten sessions is shorter than what’s typically used in practice, so this doesn’t tell us much about iTBS given for the standard 4 to 6 weeks. Operators weren’t blinded, and the single-site design limits how far these results generalize.

Practice Implications

1. Looks like patients need more than two weeks of iTBS to stay well.
2. In practice, I’ve many patients tell me they notice no difference after 2-3 weeks of TMS, even as their rating scales and the reports of relatives note improvement. That’s in line with the findings here.