Opioid pain-killers, such as vicodin, hydrocodone and oxycontin, work on the brain’s punishment and reward system. One of the key neurotransmitters associated with this system’s operations is dopamine, which creates a sense of physical and emotional well-being. This system is responsible for helping us avoid things that cause pain and develop certain habits that invoke the reward system (in cases of drug use, this leads to addiction and abuse).
That said, opioid pain-killers are generally quite effective in their role as pain killer and, for some with unbearable pain, they serve as a necessary (and ideally short-term) method of pain management. But for those with chronic pain, such as people with fibromyalgia, long-term opioid use poses risks of addiction and abuse.
What is more, they might not even be effective for people with fibromyalgia. Throughout the literature, they don’t have a stunning track record, and the reason for this may lie in observed brain differences between people with fibromyalgia and people without the condition.
The ventral tegmental area (VTA) of the brain is involved with the punishment and reward system. In a study assessing brain activity during the anticipation of pain and relief, researchers compared VTA activity in fibromyalgia patients with activity in non-fibromyalgic controls.
People with fibromyalgia were found to have notably less activity in the VTA when anticipating either pain or relief compared to control participants. This indicates that the brain’s reward and punishment system may be inhibited in people with fibromyalgia.
If this system is not working normally, then opioid medication, which acts on the system, won’t likely be helpful to people with fibromyalgia. See more on the study at psychologyofpain.blogspot.com.
Aside from giving a potential explanation for why opioid therapy is not ideal for fibromyalgia patients, this study lends yet another finding to the growing body of research aimed at uncovering the cause of fibromyalgia. The central sensitization theory posits that people with fibromyalgia process signals incorrectly to detect pain when no noxious stimuli are present; glial cells have been established as a potential source of chronic pain beyond the brain; still other research points to abnormalities in blood circulation found in patients with fibromyalgia.
While the many theories may seem disparate and confusing, researchers are working hard to nail down how they are connected. In that vein, every new finding is another helpful clue. Understanding that the VTA may factor in as a fibromyalgia cause helps point in the right direction for future research and factors into the development of therapies that, unlike opioids, may be effective.