“Depression is expected to become the leading cause of disabilities worldwide with about 20% of the population suffering from a mood disorder at least once in a lifetime (Kessler et al., 2005; de Graaf et al., 2012). Even more alarmingly, depression is characterized by high relapse rates, which increase steeply with every subsequent depressive episode, even following psychotherapy (Steinert et al., 2014). These findings underline the importance of improving existing treatments and emphasize the necessity of effective prevention instruments to interrupt this vicious circle.”
A new and relatively successful treatment is Repetitive Transcranial Magnetic Stimulation - rTMS is a non-invasive brain stimulation technique, whereby trains of brief magnetic fields are generated in a coil to induce electric fields in the nerve tissue underneath the coil, leading to neuronal depolarization. It has been shown to successfully alleviate severely negative mood states in some individuals.
The mechanisms by which it does so are as yet unknown.
see Repetitive transcranial magnetic stimulation modulates the impact of a negative mood induction in Soc Cogn Affect Neurosci. 2017 Apr; 12(4): 526–533.