Neurostimulation could be a multi-pronged treatment for depression
Many psychiatrists would say that while we treat depression in many ways, all these many treatments can be grouped into one of a few categories, usually based upon how the treatment is delivered to a patient.
For example, treatment that is ingested, such as in the form of a pill, tablet or liquid, is called pharmacotherapy.
Antidepressant drugs are the type of pharmacotherapy that most people are familiar with, although nutritional interventions, like fish oil, also represent a form of pharmacotherapy.
Another large category of depression treatment is psychotherapy or talk therapy.
Psychotherapy for depression involves the patient working with a therapist, often within the confines of a specific type of psychotherapy — for example, Cognitive Behavioral Therapy — to help them reduce their symptoms and ultimately recover from their depression.
In psychotherapy, we focus on our thoughts, so that thought patterns that commonly occur in depression are identified and addressed. This category of depression treatment is becoming as used as pharmacotherapy already is.
Perhaps a lesser known category of depression treatment is neurostimulation.
What is neurostimulation?
In neurostimulation, depressed patients’ nerve cells are exposed to electric or magnetic fields. These energy fields change how nerve cells communicate with each other and can drive improvements in symptoms and ultimate recovery from depression.
Neurostimulation can even be targeted at specific areas of a depressed patient’s brain or body, areas of the brain or body at which nerve cell communication is thought or known to be altered by depression.
Many have likely heard of a type of neurostimulation called Electroconvulsive Therapy or ECT. ECT is a very effective treatment for depression, but it is also a very controversial one for many. However, the purpose of this post is to talk about neurostimulation techniques other than ECT.
For those interested in learning more about ECT, further information can be found on the websites of many national psychiatric associations, including the British Royal College of Psychiatrists, the American Psychiatric Association and the Canadian Psychiatric Association. Moreover, you can read more about ECT in our recent blog here.
Additional neurostimulation techniques currently used and/or studied in the treatment of depression include:
Repetitive Transcranial Magnetic Stimulation, or rTMS for short, is the only neurostimulation technique listed above that relies exclusively on magnets to alter nerve cell communication in depression.
Transcranial Direct Current Stimulation (tDCS), Deep Brain Stimulation (DBS), Vagal Nerve Stimulation (VNS) and electroacupuncture (EA) all use electrical fields delivered at various sites across the body to alter nerve cell communication in depression.
Why are we interested in neurostimulation?
In a previous post, I wrote about how hormone signals caused by stress affect the functioning of the immune system in depression and vice versa.
In depression, patients with long-term increases in the blood level of the stress hormone cortisol are also often found to have very severe depressive symptoms. At the same time, these depressed patients with high blood cortisol often show changes in the function of their immune systems.
Generally, this is an over-activity of the immune system, leading immune cells to react like there is an infection in the body, but there isn’t.
All of the neurostimulation techniques listed in the above table show some ability to improve symptoms in depressed patients. I was interested in knowing whether neurostimulation could also cause changes in stress hormone levels and immune system function in depressed patients, and whether these changes may be involved in the therapeutic action of these interventions.
What did we do?
We reviewed all published studies that examine how neurostimulation affects stress hormones levels and/or the immune system in depression. This process is called a systematic review.
The systematic review method is an internationally agreed upon way to ensure that we find all published information on topic of interest, in this case, how neurostimulation affects stress hormones and/or immune function in depression.
So, what did we find?
Our work was the first to systematically review the literature on this topic.
We found that rTMS, tDCS, VNS and EA were all able to decrease elevated blood levels of stress hormones, including cortisol, and change the levels of immune signals — also known as cytokines — in depressed patients.
Interestingly, in depressed patients who experienced improvements in the blood levels of stress hormones and/or immune function due to treatment with neurostimulation, concurrent improvement in depressive symptoms did not always occur. This indicates that these changes may not always be involved in the therapeutic action, or at least not immediately.
Our systematic review identified the need for more carefully designed and conducted studies. These additional studies will allow researchers to determine if the neurostimulation techniques reviewed can improve symptoms and stress hormones/immune function in depression at the same time.
Why is this important?
Neurostimulation offers depressed patients the chance to receive a non-drug treatment for their disease. If neurostimulation techniques are proven to help the hormonal and immune system changes that accompany depression, in addition to improving depressive symptoms, then neurostimulation could represent a new multi-pronged treatment for all.
Our work therefore lays a foundation upon which more far reaching depression treatments can arise. It also highlights the possibility of combining neurostimulation with other categories of depression treatment, hopefully to generate more successful recoveries for all patients.