To report a case of hypomania induced by transcranial direct current stimulation (tDCS) given with an extracephalic reference electrode. Transcranial direct current stimulation is a noninvasive brain stimulation technique in which a weak current is applied through the scalp to produce changes in neuronal excitability in the underlying cerebral tissue. Recent clinical trials have shown promising results with left anodal prefrontal tDCS in treating depression. When the reference cathodal electrode in tDCS is moved from the cranium to an extracephalic position, larger areas of both cerebral hemispheres are stimulated, with potential implications for both efficacy and safety.
We report the case of a 33-year-old female with bipolar II disorder, on mood stabilizer medication, who had previously participated in a clinical trial of tDCS given with a bifrontal electrode montage for the treatment of major depression without incident, but became hypomanic when she received a later course of tDCS given with a frontoextracephalic configuration. Factors contributing to the development of hypomania in the second course of tDCS are examined.
No substantial differences were found in the patient's clinical presentation between the 2 tDCS courses to explain the emergence of hypomania only after the second course. The different montage used in the second course appeared to be the main contributory factor in the induction of hypomania.
The reported case suggests that frontoextracephalic tDCS has antidepressant properties and the potential to induce hypomanic symptoms. In particular, it raises the question of whether frontoextracephalic tDCS requires additional precautions when administered to bipolar patients compared to bifrontal tDCS.
From the *School of Psychiatry, University of New South Wales, Sydney, Australia; †Black Dog Institute, Sydney, Australia; ‡Mood Disorders Clinical and Research Unit, Psychiatry Department, Bellvitge University Hospital, L'Hospitalet de Llobregat, Barcelona, Spain; §Neuroscience Group, Bellvitge Biomedical Research Institute (IDIBELL), Barcelona, Spain; ∥Neuropsychiatric Institute, Sydney, Australia; and ¶St. George Hospital, Sydney, Australia.
Received for publication August 30, 2010; accepted October 8, 2010.
Reprints: Colleen K. Loo, MBBS, MD, FRANZCP, Black Dog Institute, Hospital Road, Randwick, 2031, Sydney, Australia (e-mail: Colleen.Loo@unsw.edu.au).
This study was supported by Australian National Health and Medical Research Council (NHMRC) Project Grant No. 510142. The NHMRC had no further role in the study design; collection, analysis, and interpretation of data; writing of the report; and decision to submit the paper for publication.