Friday, February 10, 2006

Cortisol Pain Memory and Psychoneuroimmunology

The Human Brain - Stress

One of the questions I had while going to the "Crazy Place" (the insurance companies multi-disciplinary pain program) this summer with a person in pain, was what the research about the effect of chronic pain on the hippocampus was. Apparently, research had shown that people with chronic pain had a shrunken hippocampus. Of course, the effects of STRESS were paramount to this program- if you could control your stress you could control cortisol secretion, was the theory. Again, it was a burden put on the patient- if only they were not stressed about the pain, the troubles getting money from the insurance company, the loss of, or threat of losing their jobs, the fact that their pain made the smallest things impossible some days.....then they could calm their brain down. Now, you know by now that I do not believe in this. I believe that chemical processes, started by inflammation of nerves and muscles due to some unknown cause (like invisible critters) set off a chain of events that becomes a chemical cascade in the brain. I think that pro-inflammatory cytokines, substance p, and other inflammatory mediatiors, including cortisol, take over and BECOME our emotions without us being aware of it at the time. Anyone who has ever raised a child has had the experience of a major change in a child's behaviour preceding an illness. Babies cannot fake it, so why do we think adults do?

I also wondered if we imaged the brains of adults with no pain who ended up being in chronic pain, what we would see. (Different people, different backgrounds, different ethnicites, different socio economics, different EVERYTHING.) Now, obviously this will not happen, because no-one is going to commit to a study that they rate their mood and their health daily, as well as come in on a forever schedule to see what happens to the brain that is developing pain. There are too many variables involved- self reporting may not be accurate, etc... Never mind the COST!!! I think might see things a bit differently if we did this. I think that the mood changes would come before the major pain, (and could be seen on MRI) and then while the pain was being experienced there would be a HUGE difference in brain images. I think if we start looking at the brain as being made of chemicals and having chemical interactions, and documenting what happens from normal to chronic pain, we might not villify those with it as much- unless of course we are attached to the PSYCHONEUROIMMUNOLOGY take on illness----which is a fancy way of saying it is the patients fault. Please read about some effects of elevated cortisol on brain function, and then scroll down and read about the PNI blame the patient psychology peoples take on pain.


Stress and Memory

Chronic over-secretion of stress hormones adversely affects brain function, especially memory. Too much cortisol can prevent the brain from laying down a new memory, or from accessing already existing memories.

The renowned brain researcher, Robert M. Sapolsky, has shown that sustained stress can damage the hippocampus , the part of the limbic brain which is central to learning and memory. The culprits are "glucocorticoids," a class of steroid hormones secreted from the adrenal glands during stress. They are more commonly know as corticosteroids or cortisol .

During a perceived threat, the adrenal glands immediately release adrenalin. If the threat is severe or still persists after a couple of minutes, the adrenals then release cortisol. Once in the brain cortisol remains much longer than adrenalin, where it continues to affect brain cells.

Cortisol Affects Memory Formation and Retrieval

Have you ever forgotten something during a stressful situation that you should have remembered? Cortisol also interferes with the function of neurotransmitters, the chemicals that brain cells use to communicate with each other.
Excessive cortisol can make it difficult to think or retrieve long-term memories. That's why people get befuddled and confused in a severe crisis. Their mind goes blank because "the lines are down." They can't remember where the fire exit is, for example.

Burgeoning research in psychoneuroimmunology (13) (the study of effects of emotion, cognition, and behavior on the endocrine, neuroimmune, and autonomic nervous systems (1,12,14)) suggests some of the neurohormonal and neuroimmune pathways by which psychological factors impact on pathophysiology in pain. For example, it is now understood that certain factors, such as negative emotional states, sleep disruption, and environmental triggers, can alter brain-stem processing in certain genetically susceptible individuals. This starts a cascade of events leading to the release of neuropeptides in the dura mater. These neuropeptides cause vasodilation and plasma extravasation in a process called neurogenic inflammation, which is critical to an understanding of migraine headache (15).

Elliot (16) points out that depression and anxiety in patients with chronic pain can alter levels of neurohormonal substances such as cortisol, corticotropin (ACTH), epinephrine, and norepinephrine. Alterations in blood levels of these substances may contribute to the encoding of state-dependent physiologic and affective responses. In other words, initial or reactive negative emotional states can have a direct impact on physiologic processes that affect the progression of chronic pain. Some investigators (17,18) believe that negative emotion manifests physiologically through altered stress hormone production and neuropeptide cascades that affect all organ systems. For example, in a recent randomized trial, Smyth and associates (19) found that patients with rheumatoid arthritis who wrote about stressful experiences and associated negative emotions experienced significant decreases in chronic joint pain.

As pain researchers from the fields of psychology and psychiatry have incorporated these findings, new diagnostic categories have been developed, such as "Psychological Factors Affecting Physical Condition" in DSM-III and "Pain Disorder Associated With Both Psychological Factors and a General Medical Condition" in DSM-IV. These changes have helped pain clinicians adopt a much more useful approach to diagnosis and intervention in the psychological dimensions of chronic pain.

Thus, the role of psychological factors in chronic pain is more complex than originally understood. In the early 1950s, intractable chronic pain might often have been considered a psychosomatic disorder. Today we realize that chronic pain constitutes a complex mixture of pathophysiologic factors interacting with numerous psychological, social, and cultural factors, including:

Depression, anxiety, and personality disorders (5,7,9)
Defective coping styles (20,21)
Autonomic stress reactions (1,10,12,14)
Lifestyle factors (22,23)
Noncompliance with treatment program (5,7,11)
Somatization (8,16,24)
Disturbances of interpersonal relationships (7,25)
Appraisal of stressful events (23)
Beliefs about control of pain (26)
Self-efficacy and cognitive distortions (21)
Involvement with disability or workers compensation programs (11,20)


Anonymous Anonymous said...

This article mentions some really interesting research being done (or that's been done in this case). I see the numbers which correspond to reference, but where can I find the reference list? Thank you! Keep up the great blog, Inpatient Patient!

Tue. Apr. 14, 12:32:00 p.m. 2009  

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