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Mild Electrical Brain Stimulation Fails to Boost Poststroke Recovery in Phase 2 Study
Key Takeaways
- Transcranial direct current stimulation (tDCS) showed no additional motor recovery benefits in poststroke patients compared to sham treatment.
- The study involved 129 patients across 15 U.S. centers, with no significant recovery differences between sham, low-dose, and high-dose groups.
In a recently presented study at ISC 2025, poststroke patients reported no additional benefit from using transcranial direct current stimulation as a potential intervention for recovery.
Wayne Feng, MD, MS
(Credit: Duke University School of Medicine)
Late-breaking findings from a phase 2 study presented at the 2025 International Stroke Conference (ISC), held February 5-7, in Los Angeles, California, showed that mild electrical brain stimulation using transcranial direct current stimulation (tDCS) did not enhance motor recovery in poststroke patients. Despite the neutral data, researchers emphasized that the intervention remains a safe and feasible option for stroke rehabilitation trials moving forward.1
Among 129 poststroke patients in the trial (average age, 59 years; women, 42%; White, 53%; Black, 41%; Asian, 3%; multiple races, 2%), no additional benefit was observed with high-dose of tDCS to amplify the effect of constraint-induced movement therapy (CIMT). All participants of low-, high-, and sham dose groups showed improvement after 2 weeks of treatment, with gains sustained at 1-month and 3-month follow-ups, but there was no significant difference in recovery magnitude between the groups. Notably, the stimulation was safe, well-tolerated, and feasible in a multi-center trial setting among poststroke patients.
“The results are somewhat surprising to us,” lead investigator Wayne Feng, MD, MS, professor of neurology and biomedical engineering at Duke University School of Medicine, said in a statement.2 “We initially hoped that a higher dose at 4 milliamps electrical stimulation had a better effect than a lower dose as well as the sham group, but we did not see that.”
The phase 2 trial, named TRANSPORT 2 (TRANScranial direct current stimulation for POst-stroke motor Recovery — a phase II sTudy), was conducted across 15 U.S. medical centers between September 2019 and September 2024 and comprised of participants who suffered an ischemic stroke 1 to 6 months earlier and retained some hand movement. In the study, patients were randomly assigned to receive sham, low-dose (2mA), or high-dose (4mA) electrical stimulation during 10 CIMT sessions over 2 weeks. Researchers assessed clinical outcomes using the Fugl-Myer Upper-Extremity Scale, Wolf Motor Functional Test and the Stroke Impact Scale Hand Subscale, with follow-ups at 1- and 3-months post-treatment to track recovery progress.
A noted limitation of the study by the investigators was the uneven representation of women across groups, as sex differences may have influenced participants’ response to brain stimulation. Additionally, authors noted that COVID-19 disruptions led to slowed enrollment and scoring inconsistencies in primary outcomes.
“In future clinical trials, we plan to enhance our approach by implementing several improvements,” Feng said in a statement.1 “These improvements will include using a higher dose – more than 4 milliamps, ensuring men and women are equally distributed in each group and ensuring consistent administration and scoring the primary outcomes across all clinical trial sites. It may take us a few attempts before we achieve success.”
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