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Dallas Nuclear Medical Researchers Help Unravel the Mysteries of the Brain
Ground-Breaking SPECT “Mood Maps” Tell Scientists Whether You’re Happy or Sad
He knows a happy person when he sees one. But, Dr. Michael Devous Ph.D, Associate Professor of Radiology at University of Texas Southwestern Medical Center, Dallas, is not looking at your smiling face. He is looking inside your head at a sophisticated nuclear image, or so called “mood map” of brain activity. For the past 12 years, his ground-breaking research has been helping to unravel the mysteries of intelligence, emotion and other brain functions and to pave the way for new and more effective treatments of depression, epilepsy, schizophrenia and a variety of mental illnesses.
Currently, Dr. Devous–who is moderating educational sessions on brain imaging at the Annual Meeting of the Southwestern Chapter of the Society of Nuclear Medicine in Dallas March 11 to 14–is focusing on the role of the brain in such psychiatric disorders as obsessive-compulsive behavior and depression as well as on advancing technologies for diagnosing epilepsy, dementia and stroke. His work is firmly establishing Dallas as one of the centers for functional brain imaging research nationwide.
Using a sophisticated nuclear imaging technology known as SPECT–Single Photon Emission Computed Tomography–Dr. Devous captures detailed images of the brain at work and identifies distinct areas responsible for particular emotions. Simply explained, SPECT nuclear imaging involves giving a patient a minute dose of a radiotracer–a chemical compound with an affinity for the organ or tissue to be imaged that has been tagged with one of several radioactive substances.
Each radiotracer travels through the body and is taken up by tissues or organs in different concentrations, depending on the chemical used. A sophisticated high-tech camera picks up the radioactive rays and creates a computerized image of the organ or tissue for clinical study or evaluation.
Nuclear imaging shows function, as organs and tissues metabolizes the radiotracer–not structure, as do other imaging techniques such as X-rays or MRI. Therefore, Dr. Devous is able to see which areas of the brain are active when a person is experiencing a particular emotion.
“In a depressed person, we typically see a reduced activity in the frontal and temporal (middle) lobes,” he says, “while the brain of a normal person would show significantly more activities in these zones.
“Pharmacological challenge” research, a unique experimental technique developed by Dr. Devous and his team in Dallas two years ago, provides the underpinnings for much of today’s breaking research on emotion and the brain. In a series of studies, nuclear images of subjects’ brains were taken before and after they were given a stimulant known to cause a feeling of elation. Clear, measurable changes in brain activity took place in response to the drug, providing a basic map of the brain areas responsible for this emotion. Today, researchers can correlate brain activity patterns with far more subtle changes in emotions and are beginning to use this information to help differentiate among specific types of mental illnesses.
As part of these studies, Dr. Devous is now comparing the response of clinically depressed subjects with normal subjects and finding that depressed people register significantly less response to stimulant drugs, suggesting a physiological cause for depression.
In another ongoing series of studies, Devous is finding several distinct but consistent brain activity patterns among the clinically depressed. “This suggests that markedly different types of depression exist that may require different treatments,” he says. “Today treating depression involves trying a series of drugs until an effective agent is found. However, in the future, brain imaging will likely pinpoint an effective drug immediately, lessening psychological and physical stress on the patient and bringing an earlier cure. This is extremely significant because severe depression is one of the most common psychiatric disorders, affecting over 10 percent of the population–and occasional situation-specific depression is far more widespread.”
Based on current research, Devous predicts that people who exhibit certain brain patterns will prove to be far more responsive to treatment than others. His studies also suggest that depression has a strong biological component because depressed patients with different brain scans show different responses to mood-altering drugs. His finding also suggest that environment plays a major role and that internal chemical cycles in the brain that bring on or alleviate stress may in turn bring on depression.
“The brain scans of those suffering from other mental illnesses, such as schizophrenia and obsessive-compulsive behavior, look quite different from depression,” he adds. “For example, in addition to significant areas of abnormal brain functioning, many schizophrenics show hyperactivity throughout the brain, suggesting an informational networking problem within the brain.
Also, a number of consistent but markedly different patterns in brain scans among those labeled as schizophrenic suggest that they may actually suffer from a grab bag of several disorders.”
“Nuclear imaging is the only technology that allows us to view physiological brain changes brought on by emotions and mental illnesses and to look at the complex and baffling interrelationship of the mind and the body,” Devous says. “What’s more, better identification, understanding and evaluation of mental illness holds tremendous promise for more effective treatment.