by When most people hear about electroconvulsive therapy, or ECT, it usually conjures up scary images of cruel, outdated and pseudo-medical procedures. Formerly known as electroshock therapy, this perception of dangerous and ineffective ECT has been reinforced in pop culture for decades – think of the award-winning 1962 novel “One Flew Over the Cuckoo’s Nest,” where a month-old patient -rustic subjected to ECT as punishment by a tyrannical nurse.
Despite this stigma, ECT is a very effective treatment for depression – up to 80% of patients experience at least a 50% reduction in the severity of their symptoms. For one of the most disabling illnesses in the world, I find it surprising that ECT is rarely used to treat depression.
Adding to the stigma surrounding ECT, psychiatrists don’t know exactly how it works in a depressed person’s brain. ECT involves using very controlled doses of electricity to induce a brief seizure under anaesthesia. Often, the best description you’ll hear from a doctor as to why that brief seizure can relieve symptoms of depression is that ECT “resets” the brain – an answer that can be vague and confusing to you. certain people.
As a data-obsessed neuroscientist, I was also unsatisfied with this explanation. In our newly published research, my colleagues and I in Bradley Voytek’s lab at UC San Diego discovered that ECT may work by resetting the brain’s electrical background noise.
Listen to brain waves
To study how ECT treats depression, my team and I used a device called an electroencephalogram, or EEG. It measures the brain’s electrical activity – or brain waves – through electrodes placed on the scalp. You can think of brain waves as music played by an orchestra. The orchestral music is the sum of many instruments together, much like EEG readings the sum of the electrical activity of millions of brain cells.
Brain waves are made up of two types of electrical activity. The first, oscillations, is like the highly synchronized melodic music you’d hear in a symphony. The second activity, aperiodical, is similar to the asynchronous noise you hear when musicians tune their instruments. These two types of activity occur side by side in the brain, together creating the electrical waves that EEG records.
The most important thing is that tuning noise and symphonic music should not be mistaken for each other. They obviously come from different processes and serve different purposes. The brain is the same in this way – the activity of oscillations and oscillations are different because the biology that drives them is different.
However, the methods that neuroscientists have traditionally used to analyze these signals are unable to distinguish between oscillations (symphony) and periodic activity (tuning). Both are critical to orchestration, but until now neuroscientists have largely ignored — or completely missed — periodic signals because they were thought to be just the brain’s background noise.
In our new research, my team and I show that ignoring periodic brain activity likely explains the confusion behind how ECT treats depression. It turns out we’ve been missing this sign all along.
Linking periodic activity and ECT
Since the 1940s, ECT has been associated with increases in slow oscillations in patients’ brain waves. However, those slow oscillations have never been linked to how ECT works. The degree to which slow oscillations are seen is not consistently related to the extent to which symptoms improve after ECT. Don’t have ideas about how the brain produces slow oscillations that link those processes to the underlying pathology of depression.
Because it is difficult to separate these two types of brain waves in measurements, I wonder if these slow oscillations were actually incorrectly measured as periodic activity. Returning to our orchestra analogy, I believed that scientists had misidentified the tuned sounds as symphonic music.
To investigate this, my team and I collected three sets of EEG data: one from nine patients with depression undergoing ECT in San Diego, another from 22 patients in Toronto receiving ECT and a third from 22 patients in Toronto who participated in a clinical trial of magnetic seizure therapy. , or MST, a newer alternative to ECT that initiates a seizure with magnets instead of electricity.
We found that periodontal activity increases by more than 40% on average after ECT. Among patients who received MST treatment, affective activity increases more modestly, about 16%. After accounting for changes in periodic activity, we found that slow oscillations do not change much at all. In fact, slow oscillations were not even detected in some patients, and their EEG recordings were instead dominated by periodic activity.
How ECT treats depression
But what does periodical activity have to do with depression?
A long-standing theory of depression says that patients with major depression are low in a type of brain cell called inhibitory cells. These cells can turn other brain cells on and off, and maintaining the balance of these on and off is critical to healthy brain function. This balance is particularly relevant to depression because the brain’s ability to switch off cells plays an important role in how it responds to stress, a function that, when it doesn’t work properly, leaves people very vulnerable to depression.
Using a mathematical model of cell type-based electrical activity, I linked increases in apical activity, similar to those seen in ECT patients, to a dramatic change in the activity of these inhibitory cells. This change in periodic activity may bring the vital balance in the brain back to a healthy level.
Although scientists have been recording EEGs from ECT patients for years, this is the first time that brain waves have been linked to this particular brain dysfunction.
Overall, although our sample size is relatively small, our results indicate that ECT and MST likely treat depression by resetting periodontal activity and restoring the function of inhibitory brain cells. Further studies can help de-stigmatize ECT and highlight new directions for research and development of depression treatments. Listening to the brain’s non-musical background noise could help solve other mysteries, such as how the brain changes during aging and with illnesses such as schizophrenia and epilepsy.
This article is republished from The Conversation, a non-profit, independent news organization that brings you facts and analysis to help you make sense of our complex world.
It was written by: Sydney E. Smith, University of California, San Diego.
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Sydney E. Smith does not work for, consult with, own shares in, or receive funding from any company or organization that would benefit from this article this article, and did not disclose any relevant connections beyond their academic appointment.
