Recent research has highlighted the dual effects of transcranial direct current stimulation (tDCS) on individuals grappling with both depression and anxiety. The study, published in the journal Biological Psychiatry: Cognitive Neuroscience and Neuroimaging by Elsevier, involved 101 participants and uncovered significant findings about this noninvasive brain stimulation method.
While tDCS was found to enhance task engagement and activate brain regions linked to executive function, it also unexpectedly increased sensitivity to threats. This complexity suggests that tDCS may serve as a supplementary treatment for those with major depressive disorder (MDD), particularly when combined with therapies requiring heightened attention and engagement.
Addressing MDD effectively poses a considerable public health challenge. Reports indicate that over half of individuals suffering from MDD do not respond to initial treatments, with high relapse rates further complicating recovery. This condition frequently coexists with anxiety disorders, which can worsen clinical outcomes and contribute to treatment resistance.
The study’s lead investigator, Maria Ironside, DPhil, from the Laureate Institute for Brain Research and Oxley College of Health Sciences at The University of Tulsa, explained the research’s focus. “We aimed to determine if tDCS could reinforce frontal brain activation while reducing amygdala activity associated with threat processing,” she noted.
Participants were divided into two groups: one received a single 30-minute session of tDCS to the frontal cortex, while the other underwent sham stimulation. Following the treatment, they performed an attentional control task involving fearful face distractions in an MRI scanner. Subsequently, they participated in an eyeblink startle task under the threat of mild electrical shock.
The results indicated that tDCS indeed improved task accuracy and reaction times, suggesting enhanced executive function. However, contrary to expectations, the intervention did not decrease threat sensitivity. Instead, it heightened responses in the amygdala during tasks of lower cognitive demand.
Dr. Ironside commented on these unexpected outcomes, stating, “Compared to the sham stimulation, frontal tDCS increased activation in the bilateral inferior frontal gyrus, a brain region associated with attention. Yet, we observed an increased amygdala response during simpler tasks, which was not anticipated.”
The Editor-in-Chief of the journal, Cameron S. Carter, MD, from the University of California Irvine School of Medicine, highlighted the clinical implications of tDCS. He noted that this method is more feasible and scalable than other brain stimulation technologies, particularly with the emergence of home-use devices. Such advancements may significantly enhance access to mental health care, especially in underserved areas.
Despite the promising nature of these findings, Dr. Ironside cautioned that the efficacy of tDCS for anxiety and depression remains uncertain. “The recent FDA approval of home tDCS for depression is encouraging. However, ongoing research is essential to better understand its mechanisms and identify which patients may benefit most,” she concluded.
This investigation emphasizes the need for further studies to explore the potential of tDCS, particularly in conjunction with therapies designed to enhance patient engagement and attention. As the search for effective treatments for MDD continues, the nuances of this research could play a role in shaping future clinical practices.
For more details, refer to the original study: Poplin, T., et al. (2025). Frontal cortex stimulation modulates attentional circuits and increases anxiety potentiated startle in anxious depression. Biological Psychiatry: Cognitive Neuroscience and Neuroimaging. doi: 10.1016/j.bpsc.2025.10.020.
