Scientists and psychiatrists alike have been increasingly interested in how electrical signals and currents can effect the human brain, especially in regards to mental health. As the US population becomes increasingly overly-medicated in general, there is a greater demand than ever for therapies to mental illness that are outside the realm of pharmaceuticals.
I’ve discussed the effectiveness of transcranial magnetic stimulation (TMS) previously, but there’s another (more invasive) therapy scientists are looking into that’s an even more direct way to apply these theories called deep brain stimulation. And it’s showing a lot of promise in treatment-resistant depression.
Dutch researcher Isidoor Bergfeld, MSc of the University of Amsterdam in the Netherlands and colleagues have published a new study in JAMA Psychiatry on the effectiveness of deep brain stimulation (DBS) in relieving symptoms in treatment-resistant depression (TRD).
Twenty-five patients (8 male, 17 female) between 18 and 65 years of age (with a mean age of 53.2 years) with TRD were entered into a 52-week open-label trial during which they underwent DBS. DBS begins with a surgical procedure in which a pacemaker-like device is implanted into the brain. This device is comprised of electrodes designed to send electrical signals to targeted areas of the brain. Placed deep in the brain, this device is then connected to a stimulator device. It functions similar to a heart pacemaker, in that it uses electrical pulses to regulate activity, in this case brain activity.
After recovering from the procedure and maintaining standardized optimization of DBS settings for at least 1 week, a psychiatrist or psychologist is tasked with assessing each patients’ response and optimizing the signals. In cases where there was little to no clinical improvement, voltages, pulse width, and frequency are adjusted. Optimization is achieved when the assessor see’s a stable response of at least 4 weeks — or a maximum of 52 weeks of DBS.
Following, researchers conducted a randomized, double-blind, 12-week crossover phase where patients received active treatment followed by sham or vice versa. Then response and nonresponse to treatment were determined using intention-to-treat analyses.
Treatment was well-tolerated, with a significant decrease in depressive symptoms observed in 10 of 25 patients and a partial response observed in six additional patients. Remission was achieved in five patients.
In six patients, the optimization period exceeded the maximum of 52 weeks, which may have led to a higher response rate, researchers acknowledged. While two responders had minor changes in antidepressant medication during the optimization phase, “it is unlikely that these minor changes explained the full response,” researchers explained.
Most importantly, patients who were receiving the sham stimulation experienced significantly more depressive symptoms than during the active treatment phase of the study, which rules out the “placebo” effect that so often can skew results.
During the sham phase, abrupt symptom increase was observed in 10 patients. Although they were blinded to treatment, they could “accurately predict the stimulation setting,” researchers noted.
“To our knowledge, this is the first study showing the efficacy of deep brain stimulation of the ventral anterior limb of the internal capsule that cannot be attributed to placebo effects,” researchers explained. “Further specification of targets and the most accurate setting optimization as well as larger randomized clinical trials are necessary.”
All patients involved in the study had a primary diagnosis of major depressive disorder (MDD) lasting for more than 2 years. They also had a 17-item Hamilton Depression Rating Scale (HAM-D-17) score of 18 or higher and a Global Assessment of Function score of 45 or lower.
While the experiment overall demonstrates a lot of potential for this therapy, there were still some negative symptoms reported including one patient who experienced severe nausea during surgery, four patients whom attempted suicide, and two patients whom reported suicidal ideation (common symptoms of MDD.)
Psychotherapy was not integrated into the experiment but psychiatrist-ordered medication adjustments—for symptom improvement, for instance—were permitted when necessary.