IEEE Spectrum magazine published an excellent deep and engaging look at how electricity is now being used to cure, or at least relieve, severe cases of depression. The techniques involve electromagnetically tweaking specific parts of the brain via implanted electrodes, current, or magnetic fields. (Previous posts on the subject here, here, and here. I also wrote about it in Popular Science in 2004.) The devices range from a "pacemaker" for your brain to a transcranial magnetic stimulator (seen here) that is used for just minutes each day but can alter your brain in the long term. From the article:
One problem with (neuropharmaceuticals) is that drugs work everywhere in the brain that their chemical target exists, regardless of whether those parts have anything to do with depression or any other disease, and that leads to side effects. Prozac, for example, has been known to reduce sex drive and can cause insomnia. Another problem is that brain chemistry varies from person to person, so no single drug will work in everyone.
The shared goal behind the new electromagnetic therapies, on the other hand, is to use electricity itself to restore the signaling, ideally, only in those parts of the brain affected by disease. Decades ago, neuroscientists demonstrated that electrically stimulating a neuron alters, in the long term, the strength of its connections to other neurons–making an electrical signal from one neuron more likely or less likely to jump to the next neuron. Though little is known in detail about how the new therapies work, it's likely that, to varying degrees, they depend on that phenomenon.