Transcranial Direct Current Stimulation for the Treatment of Bipolar Depression

Non-invasive brain stimulation therapies have been increasingly investigated in recent years as a treatment for neuropsychiatric disorders, particularly mood disorders. They are particularly appealing since many patients are either refractory or present side effects to standard pharmacological regimens. TDCS (transcranial direct current stimulation). a novel non- pharmacological brain stimulation technique, might help in overcoming some of these issues, since it has low cost, high portability and it is relatively easy to use. TDCS consists in applying a weak, direct current through two electrodes placed over the scalp; the anode and the cathode increasing and decreasing cortical excitability during and beyond the period of stimulation. It is also a safe technique with only mild adverse effects described. Previous studies, some of them from our group, have described that tDCS is an effective technique for major depression. However, the role of tDCS as a treatment for bipolar depression (BD) has been insufficiently investigated. Therefore, our aim is to address the antidepressant effects of tDCS in BD in a randomized, sham- controlled trial in a refractory sample.

BD represents the greatest burden on patients with bipolar disorder, since the depressive episodes are the most frequent and also particularly associated with suicide 7. BD treatment is controversial, with some stricter guidelines recommending only lithium, lamotrigine and quetiapine as a first-treatment, whereas others allow the use of antidepressants (which can increase manic switch and should be used in association with mood stabilizers) and other anticonvulsants and antipsychotics 8. For refractory BD the available level I evidence is very scarce, with only seven studies exploring this issue hitherto 9. Therefore, the importance of this study proposal is justified considering the burden of the disease, the paucity of current therapeutic studies and the promising results presented for tDCS in unipolar disorder.