Nice study done by Fregni et al. looking at treating depression with transcranial direct current stimulation (tDCS) for 20 min/day for five days. The patients, n=10, were divided into a control group getting sham treatment and a treatment group. All subjects were evaluated with the Hamilton and Beck Depression Inventories prior to and after treatment (or sham treatment). The treatment group HAM and BDI scores improved approximately 60% and 65%, respectively. The sham group improved 10% and 25%, respectively.
As the authors state, "The importance of this study lies in the fact that this treatment is inexpensive, easy to administer, non-invasive and painless."
They go on to say that the effects of tDCS are most likely related to neuronal depolarization and prolonged enhancement of the excitability of the left dorsolateral prefrontal cortex. This stimulation may re-equilibriate the balance of excitation/inhibition in that area of the brain.
As the basic science is accumulating, and the CNS imaging techniques improve, it seems like resetting this excitation/inhibition balance is one of the keys to neuromodulation whether it is with tDCS, TMS, pharmacology or psychological approaches.
Treatment of major depression with transcranial direct current stimulation.