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A study published in the Journal of Affective Disorders demonstrated the cognitive safety of H1-coil transcranial magnetic stimulation (TMS) treatment for individuals with bipolar depression.
The exploratory study sought to evaluate the effects of H1-coil TMS treatment on 6 cognitive domains (attention and processing speed, inhibitory control, working memory and executive function, language, immediate verbal memory, and long-term verbal memory) in subjects with bipolar depression.
Researchers recruited 50 adult participants diagnosed by board-certified psychiatrists with type I or II bipolar disorder (according to the DSM-IV), and who were experiencing a depressive episode of moderate severity at the time of the trial, which was randomized, double-blind, and sham-controlled. Of the 43 participants who finished the trial, 23 made up the sham group and 20 made up the active group. All subjects were on a stable pharmacological regimen during the trial—however, without concomitant antidepressant medications—and presented with resistant depression defined as failure to achieve remission.
The 8-week trial administered the H1-coil TMS intervention in 20 daily sessions during the first 4 weeks, followed by a 4-week period with no treatment sessions. The 6 cognitive domains were assessed using a battery of neuropsychological tests administered at baseline, and again at 4 and 8 weeks. In both sham and active groups, improvement was observed over time in all cognitive domains, suggesting that the H1-coil TMS treatment for bipolar depression is safe in terms of cognitive response.
Although the study sought to additionally assess the relationship between depression improvement and cognitive improvement, the results did not support any correlation. This suggests that cognitive impairment is likely a feature of bipolar depression rather than a symptom. Trial limitations included a small study population, the absence of a healthy control group, as well as unmedicated participants.
Cognitive dysfunction in individuals with bipolar depression often persists even after intervention, and many pharmacological therapies increase cognitive dysfunction, contributing to a poor quality of life. The demonstration of cognitive safety for the H1-Coil TMS treatment provides a compelling option for managing bipolar depression.
Reference
Myczkowski ML, Fernandes A, Moreno M, et al. Cognitive outcomes of TMS treatment in bipolar depression: safety data from a randomized controlled trial [published online April 3, 2018]. J Affect Disord. doi: 10.1016/j.jad.2018.04.022
