Fibromyalgia is a disorder that is often associated with severe, ongoing musculo-skeletal pain and stiffness, (pain and stiffness in muscles and joints), and an increased perception of pain in response to stimuli that ordinarily would not be painful (such as gentle pressure). Obviously this can be, and often is, quite disabling. It is also frequently accompanied by psychological symptoms such as depression, anxiety, insomnia (difficulty sleeping), and fatigue, among others. Although it has been around since the 1600’s, it remains poorly understood.
Because of the vagueness of some of its symptoms and the lack of any definitive test or procedure to diagnose it, its sufferers were often marginalized in terms of treatment. Physicians thought of it as primarily a psychological problem rather than a distinct physical disorder, and patient complaints of sometimes disabling pain and fatigue were often not taken seriously. However, this has begun to change in recent years, and the medical establishment now views it as a distinct and legitimate physical syndrome.
Of course, this is good news; however, if it is due to some physical disturbance, what might that be? As you might guess from the title of today’s post, there is some evidence in favor of it being due, at least in part, to altered brain function.
Altered Blood Flow
For instance, it is possible to measure blood flow to the brain very precisely, so that researchers can tell how much blood is being supplied to any given brain region at a specific time. When this was looked at in people with fibromyalgia, it was found that a region of the brain known as the thalamus, which is a structure deep within the brain, received reduced blood flow compared to people without fibromyalgia. This finding has been linked to a disturbance of pain sensitivity, and might correlate with some of the pain sensations that can occur in fibromyalgia.
It has also been shown that certain brain regions show abnormally increased activity in response to a pressure stimulus; in other words, when gentle pressure is applied to various areas of the body, these brain regions became more active than they should be. This increased activity (as measured by blood flow, which gives us an indirect measure of brain activity by the amount of blood it’s “using”) involves a number of areas, including that part of the brain that records sensation from the body, called the sensory cortex.
Neurotransmitters
The brain uses a number of chemical substances, called neurotransmitters, that enable nerve cells (neurons) to communicate with each other. Something called dopamine is one of these neurotransmitters, and there is evidence that there is a disturbance in dopamine in people that are suffering from fibromyalgia.
For example, drugs that increase dopamine activity can be effective in treating the pain associated with fibromyalgia, implying that a relative lack of dopamine activity is at least partially responsible. In addition, certain areas of the brain that are known to contain a lot of dopamine have been shown to have a lower-than-normal blood flow (which means those areas are less active than they should be), again implying that a disturbance of dopamine function is playing a role. In addition, dopamine is linked to motivation and feelings of pleasure, which might explain some of the psychological symptoms that are so common in fibromyalgia.
Brain Structure
The brain is made up of billions of neurons, along with their connections. A typical neuron consists of what is called a cell body and something called an axon. The axon functions as a signal carrier, physically conducting a message from one neuron to another. These axons are contained in the so-called white matter, so named because it appears white to the naked eye. Groupings of nerve cell bodies, on the other hand, appear gray; collectively, they are referred to as making up the so-called gray matter.
In fibromyalgia, it seems that the amount of gray matter is reduced, and the longer the duration of fibromyalgia, the greater the reduction in gray matter. Furthermore, loss of gray matter is seen in areas that are involved in the regulation of pain.
Concluding Thoughts
In conclusion, fibromyalgia appears to represent a real physical disorder; fortunately for its sufferers, this concept appears to be widely accepted by the medical community. Its cause, however, is still uncertain, in spite of what I’ve written about here. But I think it is fair to say that there is some good evidence that a disturbance of brain function may be playing a role.
References
Schweinhardt, P., Sauro, K. M., & Bushnell, M. C. (2008). Fibromyalgia: A disorder of the brain? Neuroscientist, 14, 415-421.
