Low-frequency repetitive transcranial magnetic stimulation for adolescent treatment resistant depression - a feasibility study

Depression is a debilitating mental health disorder that affects a significant portion of the adolescent population, and 20% of affected youths do not respond to two trials of treatment with antidepressants, i.e. suffer from treatment resistant depression (TRD). Repetitive transcranial magnetic stimulation (rTMS) has demonstrated efficacy in TRD in adults, but its application in the adolescent population remains relatively unexplored. This open label pilot study investigates the safety, feasibility, and potential efficacy of low-frequency (1 Hz) rTMS over the right dorsolateral prefrontal cortex (DLPFC) for adolescent TRD. Twenty patients, 13–18 years old, with treatment resistant unipolar- or bipolar depression were included (inclusion rate 0.9 patients per month) and two dropped out resulting in 18 participants completing the study (attrition rate 0.10). Daily sessions on 20–30 consecutive days with 1 Hz rTMS was administered. A significant decrease in depressive symptoms (decrease from median score of 35 to 23 on Montgomery-Asberg Depression Rating Scale, p < 0.01) and increase in function measures (increase of median score of 45 to 55 on Children’s Global Assessment Scale, p < 0.05) was observed at the end of treatment compared to baseline. However, only one patient reached the response criterium (< 50% score in Montgomery-Asberg Depression Rating Scale). Adverse effects such as scalp pain, headache, tiredness and nausea were common but tolerable, and tended to decrease during the course of treatment. In conclusion, the results of this study support feasibility of future larger studies of right frontal low-frequency rTMS for TRD in the adolescent population.