Dopamine – the Theory

Dopamine is fairly often put forward as a primary cause of fibromyalgia, and it is worth looking at it with an open mind and blinders to see what comes of it.  Looking at primary causes for fibromyalgia requires a set of blinders, because it is very easy to get overwhelmed by other possibilities, symptoms, and signs.  Since the whole point of this quest is to find an answer and hopefully be able to get some relief, the blinders are on, the mind is open, the fingers are crossed.

The theory with dopamine as the primary cause of fibromyalgia seems to revolve around stress.  The key to dopamine in fibro is suppression.  Stress suppresses dopamine production, and then there’s a chain reaction within the limbic system with changes inside the brain, particularly within the nucleus accumbens, the anterior cingulate cortex, and the insular cortex.  This creates other imbalances in hormones and chemicals, in particular adrenaline and noradrenaline, which are then elevated.

Since dopamine is the body’s natural pain-killer (analgesic), this starts the path toward chronic pain and a vicious circle, because chronic pain leads to an over-activation of the hypothalamic-pituitary-adrenal axis, which again leads to elevation of adrenaline and noradrenaline levels, and again suppresses dopamine production.  At the same time, with lower dopamine levels, there is higher dopamine utilization, like the body is trying really hard to find enough dopamine.  Once more there is a lack of pain modification as a result.

It’s not that clear cut, but essentially relatively accurate.  One thing that isn’t clear is the role of the brain iron level, which is essential for the production of an enzyme (tyrosine hydroxylase) which is necessary for regulating dopamine synthesis.  If that’s the case, is the brain iron level also an underlying factor along with stress to suppress dopamine levels?

Another foggy area is stress itself.  It is unclear if the stress that causes the suppression is necessarily psychological or physical stress or a combination of both?  Also, if stress, psychological or physical, is the root cause for the suppression of dopamine, then why is it not a universal phenomenon?  Everyone everywhere undergoes stress.  There are genetic questions in conjunction with fibromyalgia – so is it possible that there could be genetic connection that makes the body overreact to stress which kicks in the dopamine suppression?  It is possible that the key to the stress is prolongation.  Is it years of psychological stress that starts the vicious cycle rather than ordinary day-to-day stress?  Perhaps it’s the level of stress.  Intense stress as opposed to light stress.

The imbalances that result from dopamine suppression can be connected to a lot of the imbalances that have been documented in fibro patients, not 100%, but a lot, and considering that we are probably looking at a chain reaction, it could well be 100% if I was more knowledgeable, which would indicate to me that trying to regulate dopamine levels so the body has enough to work with would be helpful in breaking the vicious cycle, and there are options for dopaminergic treatment, one of which is Wellbutrin, which coincidentally is a drug I have failed…  Another possibility is NMDA (N-Methyl-D-Aspartate) receptor antagonists, which I need to closer at.

Two related pain disorders with a dopamine connection are Restless Legs Syndrome and Parkinson’s disease.

For Restless Legs, there is a basic shared mechanism: sleep deprivation/fragmentation, which in turn causes an increase in inflammation markers and thus a reduction in pain thresholds.  Furthermore, they share a common “causal pathway”: a dysregulation of the dopaminergic circuit (as above), which causes a reduction of O2 receptors (which function as a kind of pain reducer – anti-nociceptive) and a loss of pain modulation (because of an imbalance of μ-opioids in the nucleus accumbens in the brain).

For Parkinson’s there are shared symptoms and signs:

  • Autonomic dysfunction (part of the nervous system)
  • Gastrointestinal dysfunction
  • Sleep dysfunction
  • Frequent psychiatric involvement

These symptoms are connected through a reduction of FDOPA which causes a disruption of dopa decarboxylase, another enzyme related to dopamine.

Looking at related disorders may be useful for looking at fibro in terms of treatment or management.  NMDA receptor antagonists may be a common answer.

I found a list of other causes of low dopamine levels, including alcohol withdrawal, obesity, nutrition deficiency, Parkinson’s disease (interesting chicken and egg problem here), Restless Legs Syndrome (again, the chickens are pecking at the eggs), creativity (!!), drug use, sleep disorder, hypothyroidism, exposure to lead, arsenic, and cadmium, tyrosine deficiency, genetic issues with dopamine receptors, influenza, estrogen, and deficiency in human growth hormone.  It’s quite a list!