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Stress Hormones Cause Depression

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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.

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Great information Robin-


What I take away from this is that the depression associated with chronic exposure to "stress stimuli" or cortisol in a Cushing's patient is caused by some type of down regulation of response to external stimuli.

I wonder if you can correlate the longer someone has been in the throes of Cushing?s with the high levels of Cortisol the greater the risk or level of depression?


I thought this was interesting:

?Chronic exposure to corticosterone also dulled their reactions to a startling stimulus. This was another sign that their nervous system was overwhelmed."


It does make sense that a person faced with elevated chronic exposure to cortisol would reach a burn-out threshold to some degree.

That would be the point depression would kick in due to the down regulation according to what I extrapolate from the paper.

I just am having a hard time wrapping my brain around how I can go from the smallest stimuli setting me off to being so removed from a stimulus in just a matter of hours..?? Unless my body ups the level of cortisol produced when I have an "external stimulus" that does get the response thus causing a response because the level of cortisol is increased but why does it not do this the every time?

Maybe Adrenal Fatigue plays a role here. There is only so much the adrenals can produce. :)


The other idea............................

Maybe if you are a cycling Cushie you "reset" your threshold each time your cortisol dips and then low levels of stimuli DO affect you causing stress but then get to that burn-out level and thus have a down-regulation of ones reaction to the stimulus so that the same low level or even higher levels of stimuli DON'T cause a reaction until you reset again??.... :)


I need to be in that Study. :ph34r: Maybe they could figure me out?


Great food for thought thanks for posting! ;)


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