- The roots of depression
- Imaging techniques are helping neuroscientists
trace areas of the brain that may trigger
clinical depression.
Parents suffering from depression may soon be able to have their children tested for the same disorder with the latest in non-invasive brain imaging techniques. Researchers at UW-Madison already have found that the technology can provide the clearest picture yet of what happens in the brains of depressed people. They believe the scanners will eventually help clinicians identify people, particularly children, who may be at risk for depression. The UW group is among the few in the world to establish such a program. "Identifying children susceptible to depression with these safe measures should allow us to treat symptoms before they develop into full-blown depression," says research leader Richard Davidson, a professor of psychology and psychiatry. Davidson's team has adapted standard mag-netic resonance imaging techniques to develop a machine that measures blood flow in different brain regions and a scanner that reveals metabolic activity. Both techniques can provide snapshots of brain structures that become activated when a person is exposed to emotion-evoking pictures. In one experiment, researchers showed volunteers photographs of accident scenes and starving children as well as "neutral" photographs, allowing them to compare brain activity resulting from seeing both kinds of images. "We found for the first time that the amygdala,a small structure located deep in the brain, clearly relates to emotional reaction in normal humans," says Davidson. When each of the study's six subjects were shown "emotional" pictures, their amygdalas were obviously activated. But does the amygdala influence emotion in general or mainly negative emotions? Davidson next used a scanner to measure sugar metabolism, which correlates with blood flow, in various parts of the brain. "We found amygdala metabolic activity related strongly to negative, but not positive feelings, as was suspected," he says. "Moreover, we were able to predict the severity of depression by the magnitude of amygdala activity." In a third experiment, Davidson's groups used scans to determine the relationship between the amygdala and the medial prefrontal cortex, another region of the brain thought to play some role in emotions by inhibiting the amygdala. The study found that a portion of the left prefrontal cortex relates strongly to amygdala activity. Armed with the knowledge that the two brain regions are closely linked, Davidson next looked for abnormalities in the two areas in depressed patients. He observed that in such patients, the prefrontal cortex does not clamp down on the amygdala as it normally should. "This malfunction most likely leads to excessive amygdala activity, which then produces a cascade of changes that culminate in depression," he says. Davidson says neuroscientists are especially excited about their new ability to see brain structures that play central roles in emotion, particularly the way parts of the brain interact.
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- A study of their own
- Heart disease and cancer victimize women and men
alike. Finally, researchers have turned attention
to the effect of those diseases on women.
Think "heart disease" and the mental image that usually appears is that of a middle-aged male. But in Wisconsin - as in the rest of the nation - heart disease is also the leading killer of women. Yet virtually every new heart medication introduced in the last 25 years has been tested almost exclusively on men. Unfortunately, the pattern of offering treat-ments to women based on studies limited to men goes well beyond heart disease. The Women's Health Initiative, the largest clinical trial ever undertaken in the United States, is profoundly changing that picture by enrolling women as research subjects to investigate several leading causes of female death and disability: heart disease, cancer and osteoporosis. UW Medical School, selected in September 1994 to be one of 40 sites nationwide for the groundbreaking study, now is among the top recruitment sites in the nation. Sponsored by the National Institutes of Health, the study will provide answers to impor-tant questions women have asked for years: Does hormone replacement therapy reduce the risk of heart disease? Will a low-fat diet reduce breast cancer incidence? Will calcium supplements help prevent bone fractures and colorectal cancer? And, recently added to the study's agenda: Can estrogen help prevent or delay the onset of Alzheimer's disease? Finding reliable answers to those questions will require enrolling more than 160,000 women nationwide: about 60,000 for controlled clinical trials and another 100,000 for an observational study of risk factors and disease. If the UW center's success is any indication, the study will tap a deep desire to help find answers too long unknown. "We have women enrolled here in Madison from as far away as Duluth and Minocqua," notes Catherine Allen, epidemiologist at the medical school and principal investigator for the UW study with Douglas Laube, chief of obstetrics and gynecology. "I think that speaks to the willingness of women to take advantage of this opportunity to round out the research picture." More than 1,800 women have enrolled in either the clinical trials or the observational study. Study coordinators, based in Middleton, have traveled to small towns and big cities to spread the word and attract participants. One meeting last winter, organized by a parish nurse in Richland Center, attracted 35 women - despite temperatures that reached 20 degrees below zero. The "memory study," which explores whether estrogen can prevent Alzheimer's disease, was added to the initiative this summer. Earlier studies have hinted that estrogen, naturally produced by women in their child-bearing years, may offer some protection against the debilitating disorder. "This information is long overdue," says Allen. "I'm glad UW is part of this effort - and that Wisconsin women have shown their willingness to help."
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