Treatment-resistant depression is a form of major depression marked by a poor response to the treatment options typically used to address depression symptoms. When depressed people fail to respond to standard medications called antidepressants, doctors frequently rely on a form of controlled brain stimulation called electroconvulsive therapy (ECT). However, for a number of reasons, some of the people who could benefit from ECT decline use of this treatment. According to the results of a new study published in July 2013 in the journal PLOS ONE, these individuals may gain relief from monitored doses of a widely used surgical anesthetic called isoflurane.
Treatment-Resistant Depression Basics
Most people affected by major depression benefit from taking any one of a range of antidepressant medications, participating in some form of psychotherapy, or pursuing a course of treatment that involves both medication and psychotherapy. While less than 40 percent of individuals respond well to the first antidepressant they receive, depression patients frequently find adequate relief after trying one or more additional medications. In addition to switching or adding antidepressants, doctors can do such things as adjust medication dosages or simply give current medications the time they need to produce their treatment benefits. Doctors can also try any one of several psychotherapeutic approaches, including cognitive behavioral therapy (CBT), psychodynamic treatment or interpersonal psychotherapy.
Electroconvulsive Therapy Basics
Electroconvulsive therapy is the modern form of a notorious medical treatment called shock therapy. It achieves its effects through the use of doses of electrical current that produce controlled seizures inside the brain, and thereby alter the brain’s ongoing function in key ways. At one point in time, shock therapy had a well-deserved reputation for supplying too much current to the brain and producing a range of significant short- and long-term side effects. However, ECT is a highly developed procedure that provides meaningful treatment results while presenting a steeply lowered level of patient risk. Fifty to 90 percent of people with treatment-resistant depression gain at least partial symptom relief after receiving electroconvulsive therapy. However, considerable numbers of people resist using this therapy, since it carries a degree of social stigma and triggers largely outdated or misplaced concerns about such things as pain during treatment and long-term brain injury.
Potential Usefulness of Isoflurane
Isoflurane is inhaled into the lungs in small amounts as part of an oxygen-based mixture. Traditionally, anesthesiologists use the drug in combination with other anesthetic medications (such as propofol, nitrous oxide or fentanyl) to provide unconsciousness and ongoing pain relief during surgical procedures. In the study published in PLOS ONE, a team of researchers from the University of Utah examined isoflurane’s usefulness in combating treatment-resistant depression. This examination acted as a follow-up for earlier work from other researchers that suggested, but did not experimentally confirm, the drug’s suitability for depression treatment. During the study, the University of Utah researchers gave a series of isoflurane doses to eight people with treatment-resistant depression; they also gave a series of ECT treatments to 20 other people affected by the same disorder. After reviewing the results of these treatment approaches, the study’s authors concluded that both isoflurane and electroconvulsive therapy produce roughly equal reductions in depression symptoms. In the aftermath of treatment, the participants who received ECT experienced both short- and relatively long-term problems with such aspects of normal brain function as the ability to speak fluently, remember things accurately or think quickly. However, the participants who received isoflurane did not develop these problems; as a result, they maintained relatively high levels of mental function both immediately after treatment and one month later.
Considerations
No one really knows how either isoflurane or electroconvulsive therapy improves the symptoms of treatment-resistant depression. However, the authors of the study in PLOS ONE believe that both treatments may produce their benefits by temporarily lowering the amount of electrical traffic between the brain’s main nerve cells. Potential side effects of isoflurane use include nausea, vomiting and prominent mental and physical fatigue. A modern isoflurane delivery device developed at the University of Utah may help reduce the risks for these side effects by helping the body process isoflurane quickly and remove the drug from circulation. The authors of the study acknowledge the need for further, larger-scale research to build upon their findings and affirm isoflurane’s usefulness in addressing treatment-resistant depression.