Image: Shutterstock/ Yuriy Maksymiv

Fibromyalgia is one of those persistent medical mysteries. We really don’t know much about it. We don’t know why exactly it makes you hurt. We don’t know why it causes you to feel fatigued. In fact, we don’t even know what causes fibromyalgia. But that hasn’t stopped people from speculating about a huge range of theories.

So do we have any idea at all about what causes fibromyalgia? Let’s look at some of the different theories out there and see if there are any theories that might be a better explanation than others.

What Causes Fibromyalgia?

Nervous System Sensitization 

The most disabling symptom of fibromyalgia is the pain. So regardless of what causes fibromyalgia, what’s most relevant to the average sufferer is knowing why they are in so much pain. Well, to figure that out, it’s worth asking how pain works.

Essentially, pain happens in the brain. When your hand touches a hot stove, for example, it’s not your hand that’s hurting. The damaged nerves in the hand send a signal to your brain that it then interprets as pain and sends back to your hand. That’s why you feel the pain in your hand, but the hand itself doesn’t actually generate the feeling of pain.

So, in fibromyalgia, it isn’t your muscles that are the source of the pain, but the brain. After all, the muscles in someone with fibromyalgia aren’t actually damaged. That leads us to something called central nervous system sensitization.

In central nervous system sensitization, the nerves become over-active and start sending pain signals when there is no obvious source. No one is completely sure why this happen, but traumatic injury and stress both seem to contribute, as they are known to do with fibromyalgia.

It could be that fibromyalgia is the result of over-active nerves. But there are some issues with this theory. To begin with, not everyone who has CNS has all the distinctive symptoms of fibromyalgia, which implies that they are separate conditions. But, more importantly, it doesn’t really explain what causes it. It’s more of a how than a what. The over-active nerves cause the pain, but what causes the over activity of the nerves and why does that lead to the specific symptoms of fibromyalgia? That’s a question researchers are still trying to answer.

Autoimmune Conditions

Another common explanation for fibromyalgia is that it might actually be an autoimmune condition. Autoimmune conditions are things like arthritis and lupus and are caused when the body’s immune system turns against it.

In a healthy immune system, the white blood cells produce antibodies which then attack foreign cells like bacteria and viruses. But in someone with an autoimmune condition, these antibodies start attacking their own cells, destroying them and causing inflammation.

A lot of people have suggested that fibromyalgia is an autoimmune condition because of the similarity in the symptoms of fibromyalgia and other autoimmune conditions. Both conditions lead to fatigue, chronic pain around the joints, and cognitive difficulties. And in addition, people with fibromyalgia frequently develop autoimmune conditions like lupus, arthritis, and Sjogren’s syndrome.

But, doctors are able to easily diagnose autoimmune conditions because they can test a patient’s blood for elevated levels of antibodies. But while some people with fibromyalgia have elevated antibody levels, most don’t. But that doesn’t mean the immune system plays no role in fibromyalgia, and we’ll discuss why it might in a minute.

Neurotransmitters

The current theory that might best explain the cause of fibromyalgia actually puts the source in the brain. You see, your brain is full of chemicals called neurotransmitters. These are things like serotonin and dopamine, which control everything from how well your body moves to how happy you feel. And people with fibromyalgia have low levels of these neurotransmitters, which might explain their symptoms.

In fact, two of the drugs commonly used to treat fibromyalgia, Cymbalta and Savella, work by increasing the level of serotonin in the brain. That implies there’s a pretty direct link between these chemicals and fibromyalgia symptoms.

But one of the most promising theories might involve something else in the brain called microglia. Microglia are immune cells that can pass through the barrier into the brain, which might explain the relationship between fibromyalgia and autoimmune conditions. A researcher at the University of Alabama named Jared Younger has been looking into the relationship between microglia and fibromyalgia.

He found that in people with fibromyalgia, the levels of a hormone called leptin were abnormally high. And he discovered that by measuring the levels of leptin he could predict how bad fibromyalgia symptoms were. And since leptin passes into the brain, it activates microglia, which causes your body to trigger an immune response which explains the fibromyalgia symptoms.

This microglia might be what causes fibromyalgia. But until more research is done, we just don’t know for sure. But what do you think? What causes fibromyalgia? Is it the immune system? Is it microglia? Is it something else? Let us know in the comments.