The role of central dopamine

Dr Patrick Wood MD has had an article published in the May edition of the journal Expert Review of Neurotherapeutics in which he discusses the role of central dopamine in pain and analgesia [1].

Dr Wood is a respected authority on the cause and treatment of Fibromyalgia Syndrome (Fibro), who has twice been recognised by the American National Institutes of Health for his innovative research. He is Chief Medical Officer for Angler Biomedical Technologies, a private company whose primary focus is improving the understanding and treatment of fibromyalgia, and he formerly directed the Fibromyalgia Research Program and Fibromyalgia Care Clinic at Louisiana State University. Dr Wood is the originator of the Dopamine Theory of Fibromyalgia and he spearheaded the use of advanced imaging technologies, including Positron Emission Tomography (PET scans) and Magnetic Resonance Spectroscopy (MRI) to investigate fundamental changes within the central nervous system relating to Fibro. [2]

In the article, Dr Wood says that recent insights have shown that dopamine has a central role in modulating pain perception and natural analgesia within parts of the brain. Also, while the role of the neurotransmitters, serotonin and norepinephrine, in inhibiting pain (through spinal descending inhibition) is well known, it has now been shown that dopamine has a critical role in this respect too.

Decreased levels of dopamine likely contribute to the painful symptoms that frequently occur in Parkinson's disease and Dr Wood notes that abnormalities in dopamine related neurotransmission have been found in other painful clinical conditions, including burning mouth syndrome, fibromyalgia syndrome and restless legs syndrome. Evidence from animal models and indirect evidence from pharmaceutical trials apparently also suggests a role for dopamine in chronic regional pain syndrome and painful diabetic neuropathy.

The Dopamine Theory of Fibromyalgia, which Dr Wood instigated, proposes that a combination of genetic and environmental factors, such as stress and trauma, causes a reduction in the production of dopamine in the brain of people with Fibromyalgia Syndrome and the reduced levels of dopamine then go on to cause other abonormalities and cause the symptoms of Fibromyalgia Syndrome. [3]

Studies carried out by Dr Wood and his colleagues have shown that people with Fibromyalgia Syndrome have both reduced dopamine activity in the central nervous system [4] and an abnormal dopamine response to pain [5] where people with Fibromyalgia Syndrome do not release dopamine in response to pain, meaning that pain stimuli are felt as being more painful than for healthy controls.

Dr Wood says that several new classes of medication with analgesic properties have an effect on dopamine, as is shown by the capacity of dopamine antagonists to reduce their analgesic capacity. [1] The dopamine agonist, Pramipexole, has also been found to be extremely promising as a treatment for Fibromyalgia Syndrome and has been mostly studied by Dr Andrew Holman MD, who is based in Seattle. [6]

Dr Wood and Dr Holman both feature in the DVD 'Fibromyalgia: Show Me Where It Hurts' which discusses the Dopamine Theory of Fibromyalgia and the studies behind it.

In the DVD, Dr Holman says: "The study of fibromyalgia is doing so much to uncover new areas of human physiology, it’s almost unfathomable."

In the Expert Review of Neurotherapeutics article, Dr Wood says that: "An expanded appreciation for the role of dopamine in natural analgesia provides the impetus for further study ...which may lead to the development of novel therapeutic strategies."

The role of dopamine in Fibromyalgia Syndrome, the potential treatments relating to that and the knowledge that is being discovered in these studies is extremely exciting and could lead to more effective use of medications to treat Fibromyalgia Syndrome. Some doctors (mostly in the US, but including Professor John Davies at Guys Hospital, London) are already using medications that affect dopamine to treat Fibromyalgia Syndrome patients, with a promising level of success.

References:

1. Wood PB. Role of central dopamine in pain and analgesia. Expert Rev Neurother. 2008 May;8(5):781-97.
2. Kuchinad A, Schweinhardt P, Seminowicz DA, Wood PB, Chizh BA, Bushnell MC. Accelerated brain gray matter loss in fibromyalgia patients: premature aging of the brain? J Neurosci. 2007 Apr 11;27(15):4004-7.
3. Wood PB. Stress and dopamine: implications for the pathophysiology of chronic widespread pain. Med Hypotheses. 2004;62(3):420-4.
4. Wood PB, Patterson JC 2nd, Sunderland JJ, Tainter KH, Glabus MF, Lilien DL. Reduced presynaptic dopamine activity in fibromyalgia syndrome demonstrated with positron emission tomography: a pilot study. J Pain. 2007 Jan;8(1):51-8. Epub 2006 Oct 4.
5. Wood PB, Schweinhardt P, Jaeger E, Dagher A, Hakyemez H, Rabiner EA, Bushnell MC, Chizh BA. Fibromyalgia patients show an abnormal dopamine response to pain. Eur J Neurosci. 2007 Jun;25(12):3576-82.
6. Holman AJ, Myers RR. A randomized, double-blind, placebo-controlled trial of pramipexole, a dopamine agonist, in patients with fibromyalgia receiving concomitant medications. Arthritis Rheum. 2005 Aug;52(8):2495-505.