staticnrg Posted April 25, 2006 Report Share Posted April 25, 2006 Stress Hormones Cause Depression - New Drugs May Target Cortisol to Prevent Chronic Anxious Behavior and Mood Disorders April 17th 2006 Stress Hormones Cause Depression - New Drugs May Target Cortisol to Prevent Chronic Anxious Behavior and Mood Disorders Anxiety and Stress Researchers believe that long term exposure to stress causes depression. Many medical professionals have suspected this, but lacked the evidence. Neuroscientists at Harvard Medical School, and its affiliate Mclean Hospital, have shown that long-term exposure to a stress hormone in mice directly resulted in the anxiety that often comes with depression. Researchers already knew that people with depression had high levels of the human stress hormone, cortisol, but were not sure if it was a cause or effect. They now believe that long-term exposure to cortisol actually contributes to the symptoms of depression. Scientists exposed mice to both short term and long-term durations of the rodent stress hormone, corticosterone. According to Paul Ardayfio, PhD candidate, and Kwang-Soo Kim, PhD, chronic stress, such as caring for a spouse with dementia, rather than acute stress, has been associated with depression. The researchers used 58 mice for their study. They put hormones in the drinking water. They considered chronic doses to be 17 to 18 days of exposure and acute doses were 24 hours of exposure. Then they used a standard test to evaluate anxiety in animals. Mice that received the stress hormone for more than two weeks took significantly longer to emerge from a small dark compartment into a brightly lit open field. They seemed more fearful and were less willing to explore their new environment. Chronic exposure to corticosterone also dulled their reactions to a startling stimulus. This was another sign that their nervous system was overwhelmed. This is likely the first experiment that compared the effects of chronic corticosterone with the effects of acute corticosterone on anxiety-like behavior. These new findings did not surprise researchers, especially since more than half of the people with Cushing's disease, in which a disordered adrenal system releases too much cortisol, have depression and anxiety. Researchers already knew that the "anxious-retarded" subtype of depression is commonly associated with disruption of that same hormonal system. They also were aware that people getting corticosteroid therapy for inflammatory and other disorders have increased mood-related side effects, including anxiety and depression. Another reason doctors have suspected that stress causes depression is because higher glucocorticoid levels for chronic periods have been linked to increased activity in anxiety-related brain regions such as the amygdala in both rodents and humans. The authors wrote, "Our results suggest that chronically high levels of cortisol, which occurs in Cushing's disease and some subtypes of depression, can increase anxiety on the one hand and dull responses to external stimuli on the other." The difference between the responses to acute and chronic hormone exposure strengthen the view that very-short-term or acute exposure, they add, "may be adaptive, whereas chronic exposure has detrimental effects on brain and behavior." It is hoped the research will help doctors design new psychiatric drugs that treat the causes of depression rather than the peripheral disease-related phenomena. Ardyflo and Kim speculate that drugs that reverse or block the deleterious effects of chronically elevated stress hormones may help guard against some types of anxiety symptoms in depression, citing the preclinical evidence in rats. The research appears in the April issue of Behavioral Neuroscience, which is published by the American Psychological Association. Quote Link to comment Share on other sites More sharing options...
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