New research demonstrates that functional MR imaging (fMRI), a dominant brain imaging tool since the early 1990s, is playing an important role in understanding and treating serious depression.
Researchers in Scotland used fMRI to show how electroconvulsive therapy (ECT) works in treating major depression, while investigators in the People's Republic of China have demonstrated the potential for fMRI to provide effective biomarkers for clinically diagnosing serious depression.
In an article published in the April 2012 edition of the journal Proceedings of the National Academy of Sciences, lead researcher Ian Reid, M.B.Ch.B., Ph.D., M.R.C.Psych., a professor of psychiatry at the University of Aberdeen, and colleagues used fMRI to demonstrate how using ECT in depressed patients affects the way that different parts of the brain communicate with each other.
ECT has a long and controversial history. It was first used in the 1930s based on the theory that schizophrenia and epilepsy could not co-exist and that clinicians could "drive out" mental illness by using electricity to induce fits, Dr. Reid said. "Of course, that was entirely mistaken—epilepsy and schizophrenia often co-exist," he said. "But over time it was determined that ECT could be effective in treating severe depression."
Yet, Dr. Reid said, no one has ever "pulled together a coherent picture of how ECT works in terms of the knowledge of the etiopathology of depression."
Dr. Reid and colleagues used fMRI to scan the brains of nine severely depressed patients before and after they received ECT. fMRI and data-driven analysis revealed that ECT reduced the global functional connectivity in the left dorsolateral prefrontal cortical region of the brain in all nine patients. Simultaneously, this reduced connectivity was accompanied by an improvement in symptoms as reported by the patients.
"Essentially, it appears that ECT reduces hyperconnectivity between parts of the brain involved in mood, thinking, concentration and memory," Dr. Reid said. "If you talk to patients, they will tell you that it does feel like that—like someone has turned down this painful depressive sense after ECT."
Performing ECT requires an anesthetic and a hospital stay and can have potentially serious side effects, including memory loss. Consequently, ECT is recommended only for patients with severe depression who require a fast, responsive treatment, Dr. Reid said.
ECT remains "a very controversial treatment," Dr. Reid said. While the conventional medical view is that ECT is useful and safe, there are those who consider it "outmoded and barbaric," he said. "The criticism against it has been, 'How can it possibly make sense—how does giving someone electric shocks and making them have a fit help depression?'" he said. "Because our study answers that question to a point, it may help ECT to become more acceptable to those thinking about the treatment. How it works is no longer a complete mystery."
In addition, the effect of ECT parallels a variety of anti-depressive treatments. "If we can replace ECT with a less invasive treatment that produces similar neurophysiological changes with fewer side effects, we would be doing depressed patients a real service," Dr. Reid said. "Because we now have a handle on what effects need to happen, evaluating known treatments for depression could become much easier."
Investigators from several universities in the People's Republic of China used resting-state fMRI to help identify patients suffering from major depression. Their research was published online in the March 14 edition of the journal Brain.
A research team led by Dewen Hu, Ph.D., a professor in the College of Mechatronics and Automation at the National University of Defense Technology in Changsha, Hunan, used multivariate pattern analysis to classify 24 depressed patients from 29 demographically similar volunteers. Researchers identified depressed individuals from healthy controls with 94.3 percent accuracy.
"Our findings suggest that the disease-related resting-state network alterations, including abnormalities in the default mode network, affective network, visual cortical areas and cerebellum, may give rise to a portion of the complex of emotional and cognitive disturbances in major depression," Dr. Hu said.
The study also suggests that the brain's amygdala, anterior cingulate cortex, parahippocampal gyrus and hippocampus could play important roles in the pathophysiology of major depression, Dr. Hu said.
"Whole-brain resting-state fMRI may provide potential effective biomarkers for the clinical diagnosis of major depression," Dr. Hu said.
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