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The details of a new case study reveal how deep brain stimulation helped a woman with treatment-resistant depression achieve full remission. undefined/Getty Images
  • The case study reports that researchers identified a biomarker for a woman’s treatment-resistant major depressive disorder by mapping electrical activity in her brain.
  • They then used a device that doctors use to treat epilepsy to disrupt abnormal activity associated with depression using small 6-second bursts of electricity.
  • This treatment reduced depression in just 12 days, and the woman was in complete remission several months later.

Deep brain stimulation is a treatment that involves placing electrodes in parts of the brain to disrupt certain brain circuits. Doctors have used neurostimulation devices designed to deliver this treatment to treat people with Parkinson’s disease and those with epilepsy.

Experts have thought for some time that deep brain stimulation could serve to treat depression, particularly for people who have not responded to other treatments. However, the parts of the brain that depression affects may vary among individuals, so there is a need to tweak the devices that exist to make them suitable for treating depression.

Now, researchers from the University of California, San Francisco (UCSF) have shared the case study of a woman named Sarah, who had treatment-resistant major depressive disorder. Doctors successfully treated her using a neurostimulation device adapted to her specific needs.

The details of the case study appear in the journal Nature Medicine.

Dr. Katherine Scangos, assistant professor in psychiatry at the UCSF Weill Institute for Neurosciences and lead author of the paper, said this research showed that psychiatrists might be able to offer more personalized medicine in the future.

She said: “Evidence this kind of therapy can work provides hope to patients and is certainly something that is meaningful to me, in that we as psychiatrists will be able to help people with mental illness.”

“I think it suggests there could be a whole other type of treatments that are based on biomarkers that can deliver treatment in short time frames rather than antidepressants, which act on much longer time frames.”

– Lead author Dr. Katherine Scangos

The first challenge for researchers was finding a “biomarker” for Sarah’s depression. This information would allow them to detect the abnormal brain activity causing the depression, so they could target the electrical bursts to disrupt the right area at the right time.

Existing neurostimulation devices deliver constant electrical stimulation to the brain, so the team needed a way to detect and disrupt brain activity related to the depression when it was occurring.

To do this, the researchers carried out brain mapping, placing 10 electrodes across the left and right hemispheres of Sarah’s brain and recording neural activity across 10 days. Sarah reported the severity of her depressive symptoms using symptom rating scales during this time.

The researchers found that gamma frequency brain waves in a part of the brain known as the amygdala were most closely correlated with depressive symptoms. They could, therefore, use these as a biomarker for her depression.

Next, the researchers had to figure out how to disrupt these brain waves. They found that placing an electrode in the ventral capsule/ventral striatum at the base of the brain gave the most consistent improvement of symptoms when they applied electrical stimulation upon detecting abnormal brain activity in the amygdala.

Optimization of this process showed that applying very small amounts of electricity — 1 milliampere — for just 6 seconds at a time was sufficient to improve Sarah’s symptoms.

Sarah, who had experienced major depressive disorder since childhood, started the trial reporting a score of 36/54 on the Montgomery-Asberg Depression Rating Scale, which measures the severity of depressive episodes.

Neither antidepressants nor electroconvulsive therapy had successfully treated her depression. However, on starting treatment with the neurostimulation device, she reported that her depression dropped from 33/54 on the scale to 14/54 in just 12 days.

It then dropped to below 10 within several months of starting the treatment and has stayed there for longer than a year (15 months), which means that she is in remission from her depression.

Both the team who treated her and other researchers are keen to point out that this case study only demonstrates the effectiveness of this treatment in one person. However, the fact that the paper outlines a way to customize this neurostimulation has demonstrated a personalized approach to psychiatric treatment not seen before.

Dr. Robert Greenberg, who is an associate clinical professor of psychiatry at the New York University School of Medicine and was not involved in the study, told MNT: “Regarding the study in question, we are learning, especially in the fields of neurology and psychiatry, that many of the syndromes we treat are complex and heterogeneous, and we cannot expect that ‘one size treatment fits all.’ Patients with overlapping symptoms may have very different pathways for their development.”

“This has led to recent attempts to understand the individual pathophysiology of disorders and individualize treatment to a much greater degree than previously possible.”

Since running the experiments with Sarah, the team has enrolled two more people in a trial and hopes to enroll nine more.