Researchers have shed new light on why electroconvulsive therapy is so effective, a mystery that has baffled doctors and scientists for nearly a century. The findings could help improve this contentious treatment.
Electroconvulsive therapy (ECT), formerly known as electroshock therapy, involves using controlled doses of electricity to induce a brief seizure in the brain. While ECT is extremely effective for certain mental illnesses, particularly depression, the reasons for its effectiveness have long perplexed researchers in psychiatry and neuroscience.
Researchers at the University of California, San Diego, believe they have found an answer. Two new studies published in Translational Psychiatry propose a new hypothesis that ECT alleviates depression symptoms by increasing aperiodic activity, a type of electrical activity in the brain that does not follow a consistent pattern and is generally considered to be the brain’s background noise.
“We’re solving a puzzle that has baffled scientists and doctors since electroconvulsive therapy was first developed nearly a century ago,” said first author Sydney Smith, a PhD candidate at UC San Diego’s Voytek Lab. “On top of that, we’re also helping to demystify one of the most effective, yet stigmatized treatments for severe depression.”
A lot of people are surprised to learn that we still use electroconvulsive therapy, but the modern procedure uses highly controlled dosages of electricity and is done under anesthesia. It really doesn’t look like what you see in movies or television.
Sydney Smith
Electroconvulsive therapy has a positive track record but a negative reputation. The therapy is effective in up to 80% of patients who receive it, most commonly for depression, but also for bipolar disorder and schizophrenia. Despite its high success rate, electroconvulsive therapy is frequently associated with images of people receiving painful, high-voltage shocks.
“A lot of people are surprised to learn that we still use electroconvulsive therapy, but the modern procedure uses highly controlled dosages of electricity and is done under anesthesia,” Smith said. “It really doesn’t look like what you see in movies or television.”
While generally safe and effective, ECT does have drawbacks, including temporary confusion and cognitive impairment. It also requires multiple outpatient visits, which can present a barrier to some people who might otherwise benefit from the treatment.
“One of the reasons ECT isn’t more popular is that for a lot of people, it’s easier and more convenient to just take a pill,” said senior author Bradley Voytek, PhD, professor of cognitive science at UC San Diego. “However, in people for whom medications don’t work, electroconvulsive therapy can be life-saving. Understanding how it works will help us discover ways to increase the benefits while minimizing side effects.”
The researchers used electroencephalography (EEG) scans to study the brain activity of patients who received ECT therapy for depression. They also looked at another similar form of treatment called magnetic seizure therapy, which induces a seizure with magnets instead of electrodes. Both therapies showed increased aperiodic activity levels in patients’ brains post-treatment.
“Aperiodic activity is like the brain’s background noise, and for years scientists treated it that way and didn’t pay much attention to it,” Smith said. “However, we’re now seeing that this activity actually has an important role in the brain, and we think electroconvulsive therapy helps restore this function in people with depression.”
Aperiodic activity in the brain assists in controlling how neurons turn on and off. Our neurons are constantly cycling between excitation and inhibition, which correspond to different mental states. Aperiodic activity increases inhibitory activity in the brain, slowing it down.
“Something we see regularly in the EEG scans of people who receive electroconvulsive or magnetic seizure therapy is a slowing pattern in the brain’s electrical activity,” he said. “For many years, this pattern went unnoticed, but accounting for the inhibitory effects of aperiodic activity helps explain it.” It also implies that these two types of therapy have similar effects on the brain.”
While these findings establish a link between aperiodic activity and ECT benefits, the researchers emphasize the need for additional research to apply these findings in clinical settings. They are currently investigating the use of aperiodic activity as a metric of treatment efficacy in other depression treatments, such as medications.
