Ian Reid, a psychiatrist at the Royal Cornhill Hospital in the Scottish city of Aberdeen, has treated people with severe depression for 25 years. “It’s a very nasty illness, depression,” he says. “I have worked with people who have cancer and depression, and more than one of them has said, ‘If I had to choose one of those two diseases, I’d go for the cancer.’ ”

When patients come to Royal Cornhill with major depression, they’re first treated with psychotherapy and antidepressants. Only about 40 percent respond to their first medication. Sometimes a different one will do the trick, but in Reid’s experience, about 10 to 20 percent of depressed people respond to no drug at all. In those cases, Reid regularly shifts to a third option. It’s officially called electroconvulsive therapy, or ECT—better known by its unofficial name, shock therapy.

Reid is an expert on ECT, and over the years he has received plenty of grief for it. “There are people on the Internet who describe me as a Nazi, as a barbarian,” he says. “And there’s one person who suggested I should get ECT so I know what I’m doing.”

Reid is not surprised by the reactions. For many people, the sum of their knowledge about ECT comes from the 1975 movie One Flew Over the Cuckoo’s Nest. Jack Nicholson plays Randle McMurphy, a criminal hoping to escape hard labor by spending his term in a mental institution. But McMurphy gets more than he bargained for, including a harrowing session of ECT. The hospital staff straps him down, puts a piece of rubber in his mouth so he won’t bite off his own tongue, and delivers a blast of electricity to his temples. He writhes in agony and then slumps back, his body limp.

That scene bears no resemblance to what Reid does for his patients. For one thing, he gives them anesthesia and muscle relaxants so they don’t experience any flailing. But most crucially, ECT works. “You can watch someone going from being unresponsive and soiling themselves to being completely transformed,” Reid says.

In Scotland, a country of 5 million, 400 people receive the treatment each year. And for about 75 percent of them, it brings relief. “ECT outperforms psychotherapeutic treatments and antidepressant drugs,” Reid notes. Yet its effectiveness is a mystery. “It doesn’t sound intuitive at all,” he admits. “Making someone have a seizure, giving them an electric shock, and making something as complex as depression better just seems crazy.”

Shock Therapy in Analysis
Fortunately, we don’t have to understand why a treatment works before using it. “Captain Cook was handing out limes to his crew for scurvy before anyone knew what vitamin C is,” Reid says. But since ECT is so invasive, and since its effects can fade, he has long wanted to figure out how shock therapy works, in the hopes of tapping the same mechanism to find a longer-lasting, less arduous means of beating back depression. “Always in the back of my mind has been the thought that it would be awfully nice to know what was going on here,” he says.

Doctors in Italy first used electroconvulsive therapy in 1938 to treat schizophrenia; in the decades that followed, the treatment spread to other countries and other disorders, especially depression. Although ECT was clearly effective, it could be a frightening experience. Patients remained conscious until their seizures made them black out. Sometimes they broke bones during the process. In the 1960s, psychiatrists added anesthesia and muscle relaxants to ECT to eliminate some of this trauma, but memory loss was still a common complaint. Amnesia became less of a problem in the 1980s, when pulses were reduced to brief, sharp stimulations.

By the 21st century, the negatives surrounding ECT had been mitigated to a large degree. In a 2010 study, Maria Semkovska and Declan M. McLoughlin of Trinity College in Dublin reviewed 84 studies of 2,981 patients who received ECT. The only significant memory troubles they found occurred within three days after treatment; by 15 days, the patients’ memories actually improved.

With safety questions put to rest, Reid and his colleagues have been trying to find out how ECT works. Beginning in 2009, they used functional magnetic resonance imaging (fMRI) to scan the brains of patients prior to treatment for depression; they then followed the patients through the course of therapy, generally for four weeks. Successfully treated patients, nine in all, returned for follow-up scans. Reid knew from previous studies that depression reduces the size of certain brain regions, including the hippocampus and gray matter, both generally implicated in emotion. After ECT, Reid’s team measured the volume of each subject’s brain. The researchers found an increase in hippocampus size but not in gray matter.