Posted by Elroy on June 19, 2005, at 9:49:11
Chronic stress can make you clinically depressed. Stress- either physical or emotional stress- produces a cascade of different hormonal changes in the body.
These hormones act in a feedback called the HPA (hypothalamic-pituitary-adrenal) axis. Stress prompts the release of CRF (cortisol releasing factor) from the hypothalamus. CRF alerts the pituitary gland to secrete ACTH (adrenocorticotrophin hormone). Then ACTH tells the adrenals to produce more cortisol.
Like adrenalin, cortisol is an essential stress hormone without which we would not survive. However, too much of it can be damaging, especially to the heart, brain, muscles and organs.
Fortunately, cortisol inhibits further secretions of CRF and ACTH, thus completing the feedback loop and shutting down any excessive
secretions of CRF. These mechanisms are essential to stop the HPA axis from damaging the body.
When something goes wrong, and the HPA axis secretes cortisol at dangerous levels, a whole plethora of familiar stress-induced diseases and mental complaints can arise.
The HPA axis drives the famous fight-flight response. Under threat, adrenalin rises, heart rate and blood pressure increases, and blood flows to the muscles for running and fighting.
However, when acute stress becomes chronic and long-term, then cortisol becomes the dominant hormone in positioning bodily functions to handle the stress.
Many of the normal bodily processes shut down for the perceived continuing emergency: cell reproduction slows, organ function slows, the immune system becomes suppressed, sleep is more difficult, but appetite actually increases (this is why cortisol is linked to weight gain).
Other effects include lowered sex drive, damage to brain areas including the hippocampus (where emotional memories are stored), distortion of neurochemical receptor sites (because cortisol reduces expression of the gene that produces the 5-HT1A serotonin receptor), destruction of neurons, and damage to the heart.
The destructive consequences of prolonged exposure to cortisol have led some health researchers to speak of "cortisol poisoning". It is easy to see why roughly 50% of severely depressed patients who have been tested have elevated cortisol levels.
In addition, chronic severe stress in newborns can damage the HPA axis itself, and cause increased sensitivity to stress in later life. This is partially why children who have a traumatic childhood are more prone to anxiety and depression later on.
The HPA axis evolved to help people cope with physical stress. Unfortunately, the HPA axis is also stimulated by emotional stress. The more primitive areas of the brain have great difficulty distinguishing between an imagined threat, and a real one. That means that over time, worry can be as dangerous a stressor to your body as real physical danger.
When The HPA Axis Shifts Into Overdrive
Prolonged stress may help create abnormalities in the HPA axis that can lead to depression. These abnormalities include raised levels of CRF and cortisol, abnormalities of the cortisol receptors, causing the HPA feedback loop to be constantly overactive, even when excess cortisol should shut down secretions.
How does cortisol cause depression?
Unremitting stress causes a continual release of cortisol that can transform anxiety into depression by depleting levels of dopamine. This denies dopamine to the pleasure circuitry of the prefrontal cortex, as well as other pleasure pathways, literally preventing the sufferer from feeling good.
The increased cortisol acts like an steroid bombardment on neurotransmitters involved in depression, influencing both the formation and breakdown of serotonin and noradrenaline (which are the targets of modern antidepressant drugs such as selective serotonin reuptake inhibitors). At the same time cortisol may disrupt the receptor sites for these neurochemicals. These are the likely mechanisms of cortisol's contribution to depression.
SSRIs (selective serotonin reuptake inhibitors) have been shown to reverse the damage done to the HPA axis, and to reduce damage to the hippocampus done by excessive cortisol. This is another example of the interrelationship of stress, the HPA axis, and depression.
Psychologists have long understood that severe chronic stress can cause depression. Genetic predispositions to stress related depression are probably common. Unfortunately, depression, even when caused by other means, is a major psychological stressor that can also active the HPA axis and release cortisol, which may further contribute to depression.
In short: stress, anxiety, and depression can exist in a feedback loop that contribute to the further degeneration of these conditions. By the same logic, many treatments that interrupt the HPA axis and lower cortsiol have the potential for alleviating both stress/anxiety and depression.
If you are concerned about your cortisol levels, then you should find a good endocrinologist, in order to receive specialized and complex
In other words, long-term stress, chronic low-level anxiety or a severe trauma incident can ALL lead to a situation where the HPA Axis begins to wear down and soon becomes dysfunctional. At somepoint the cortisol becomes the dominant adrenal hormone being released and a condition of elevated cortisol exists. As specified above, elevated cortisol not only exaggerates the condition by actually "manufacturing" anxiety and/or depression (by its negative impact on neurological systems), but can create a number of physical symptoms also (and there's no set pattern as individuals react differently to different levels of elevated cortisol).
The first step that needs to be done is to verify cortisol levels through the employment of three 24-hour UFC tests (that's Urinary Free Cortisol). If those levels (any one of the three) come back as lelevated above the lab's normal reference range, then the first step is to determine if this is depression and / or anxiety induced Pseduo Cushing's, or if there's a possibility that one might be dealing with a physical caused form of Cushing's (usually a pituitary tumor, an adrenal tumor or an ACTH-secreting cancer). That is best done through the use of three "Late Night Salivary Cortisol tests". They are as simply as spitting required amount of saliva into a test tube between 11 PM andMidnite and then mailing the sealed tubes back to the lab. levated levels in saliva cortisol amounts (for that time of day) will be likely indicators of Cushing's Disease or Cushing's Syndrome and require further advanced testing.
More to come...