FDA Approves At-Home tDCS — But Should It Have?

The approval of Flow tDCS gets a closer look

STUDY: Klaus J et al, Lancet Psychiatry 2026

STUDY TYPE: Expert commentary

FUNDING: Independent

Background

Transcranial direct current stimulation (tDCS) modulates brain activity with a low electrical current applied to the scalpy. On December 8, 2025, the US FDA approved home-based tDCS device (Flow FL-100) for moderate-to-severe major depressive disorder. This Lancet Psychiatry commentary argues the evidence doesn’t justify it.

The Problems

• The approval rests on a single randomized controlled trial of 173 patients.
• The blind failed in the trial, with 78% of patients guessing their treatment correctly. More concerning, the benefit disappeared when researchers controlled for treatment beliefs, suggesting the unblinding gave a false positive read on the device.
• There are another 30+ trials of tDCS in depression, but meta-analysis of home-based tDCS found a Hedges’ g of just 0.10 (Aiken’s note: true, but another analysis landed at 0.24-0.46).
• The device as sold also limits sessions to twice weekly after week 3, whereas the trial used three sessions per week — meaning the approved real-world protocol differs from the one that generated the data.

Practice Implications

1. FDA approval does not mean what it used to.
2. On the one hand, tDCS has 30 years of support from clinical trials numbering over 30.
3. On the other hand, the data is not as robust as it is for older FDA approvals, and tDCS does not bring any benefit when antidepressants fail.

— Chris Aiken, MD
Director, Psych Partners
Editor in Chief, Carlat Psychiatry Report

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