Before we go any further, we should make it clear that a small number of people with really severe mental illnesses receive ECT. About 100,000 Americans undergo ECT each year, while nearly 14.8 million Americans report depression annually [sources: Reti, NIMH]. Although the therapy was once used for a variety of mental disorders, it's now employed almost solely for severe depression or some symptoms of mania [source: NAMI].
While the treatment was always controversial, its popularity waned quite a bit with the introduction (as well as the improvement and variety) of antidepressants and other drugs for mental illnesses on the market. For example, in England between 1985 and 2002, ECT's use more than halved [source: Royal College of Psychiatrists]. In fact, one of the main instances when clinicians turn to ECT is after many different medications have been proven ineffective in treating a patient's severe depression.
Until recently, there's never been proof of how exactly the seizure works to improve mental health. Some theories have to do with the physiology of the brain. It's possible that the seizures can change how blood flows through the brain or the metabolism in certain areas [source: Royal College of Psychiatrists]. Because depression is often treated through chemical means, it's also possible that ECT causes a release (or improved functioning) of certain chemicals in the brain. More research also indicates that ECT can stimulate cell growth and nerve pathways, which might link to improved mood [source: Royal College of Psychiatrists].
A study published in 2012 suggested that an over-communicative brain might be an issue in depression. Shocking the brain might work like turning down a stereo, according to one of the study's authors, allowing a severely depressed patient to think a little more clearly [source: Rettner].
There have also been several studies done with placebo treatments, which point out the effectiveness of ECT. Essentially, the patients receive the exact same treatment -- anesthesia and muscle relaxant included -- and are told they had the shock, but don't. The patients with the actual ECT treatment did recover from their illness much faster. However, some patients with the fake treatment recovered as well, perhaps because of the extra clinical attention [source: Royal College of Psychiatrists]. In severe depression, the treatments do appear to be more effective than medication [source: Royal College of Psychiatrists].
As we talked about earlier, the side effects have also improved quite a bit with modern practice. Headaches are reported, as is muscle pain. There are still memory issues, as well: One-quarter to two-thirds of patients report memory problems after ECT [source: NAMI]. Some patients report having trouble forming memories after the treatment, while others say they have a hard time remembering some events before the therapy. Also, there can be initial confusion after the procedure, which isn't uncommon to coming out of sedation in general.
But that doesn't mean it still doesn't court its fair share of controversy. It's not hard to find groups that oppose the practice. Some are adamantly anti-psychiatry in general, while others claim that long-lasting damage is done to cognition and memory, as well as just being generally ineffective [source: Wilson].