By Jenny Geyer
What is the cost of having chronic pain go untreated, or undertreated? For those individuals affected, it can cause severe psychological problems and have an overall negative impact on a person’s quality of life. According to a 2011 report by the Institute of Medicine (PDF), the 100+ million Americans who struggle with chronic pain end up costing the nation over $600 billion “in medical treatment and lost productivity.”
One reason the problem persists is that existing pain management therapies do not effectively treat certain kinds of pain. One size does not fit all when it comes to pain relief, and the cause of chronic pain can be traced to a wide range of conditions, including everything from lower-back pain to fibromyalgia. Despite the widely varying differences in the source and degree of severity of chronic pain, many continue to be treated with opioids—a class of drugs known to cause dependency and tolerance—and may lead to harmful side-effects when prescribed long term.
Drug developers have recognized the need for alternative therapies and have learned that understanding pain pathways by tracing their sources is crucial to formulating effective treatment plans for patients suffering from chronic pain. The brain’s systems that register and regulate pain overlap with the systems that manage emotions such as fear, anxiety, and anger, and can intensify pain perception. Because we know the neurochemistry of emotion and physical pain share similar qualities, one approach researchers have taken is searching for methods of inhibiting pain signals traveling between the brain and spinal cord to decrease the pain felt by the patient. These signals (chemicals called neurotransmitters) communicate with receptors (protein molecules on the surface of a cell) which then receive those signals and relay or block the message. While prescription opioids help diminish pain felt by attaching to receptors and increasing the flow of the body’s natural painkillers (like dopamine and serotonin), gamma-aminobutyric acid (GABA) and glutamate are major inhibitory neurotransmitters that can block neurons from transmitting pain signals.
There has been a strong focus in pharmacological studies to learn more about how these chemicals affect pain perception, which will likely be a key component in the future of drug development for targeting neuropathic pain. Some therapies have already successfully made it to market. Though initially developed to treat epilepsy and prevent seizures (e.g., pregabalin and gabapentin), some therapies have been found to have a broader purpose in treating neuropathic pain caused by diseases such as shingles (herpes zoster) and fibromyalgia. But there is still much more to learn as dangerous cognitive side-effects in some patients have been found as a result of taking GABAergic drugs.
Though the treatment of chronic pain remains a difficult and multifaceted challenge, ongoing research and awareness has helped progress doctors’ and drug developers’ understanding of the complexity of pain perception and management.