Ouch! Just when you thought the headlines about opioids couldn’t get any worse... A study published today reports (for the first time) that even short-term use of opioids may increase and prolong chronic pain.
An international team of researchers has discovered that opioids paradoxically increased chronic pain in lab rats by exacerbating the release of pain signals from specific immune cells in the spinal cord. Although this was an animal study, the findings could have far-reaching implications for humans, too.
The May 2016 study appears in the Proceedings of the National Academy of Sciences. The research was led by Peter M. Grace and Linda R. Watkins of University of Colorado Boulder's Department of Psychology and Neuroscience.
Ironically, the ability of opiate-based (narcotic) medications—such as morphine, codeine, oxycodone, percocet, and other opioids—to reduce pain appears to backfire by making users more sensitive to pain over time. Also, as people develop a tolerance to these medications, they often take higher doses of painkillers which causes this entire conundrum to snowball out of control.
Typically, a peripheral nerve injury in a rat sends signals from the damaged nerve cells to spinal cord immune cells known as glial cells. Once the bugle is sounded by a pain signal, the glial cells kick into a hyper-vigilant alert mode which primes them to act as "housekeepers." A primary function of glial cells is to 'clean house' by getting rid of unwanted debris and microorganisms.
Unfortunately, this new study has identified that when opioids are introduced into this process—and once a peripheral pain signal has been sent—the glial cells go into overdrive. Eventually, this cascades into a chain reaction that increases inflammation of the spinal cord and the activity of pain-responsive nerve cells in the brain.
In fact, the researchers found that just five days of opioid treatments could trigger chronic pain that lasted for several months. The ultimate double whammy is that as the pain increases, oftentimes, the use of opioids also increases. This creates a vicious cycle that can lead to opioid addiction. When prescriptions run out, many addicts turn to heroin, which is cheaper and readily available.
“The results suggest that the recent escalation of opioid prescriptions in humans may be a contributor to chronic pain,” lead author, Peter Grace, said in a statement. Adding, "We are showing for the first time that even a brief exposure to opioids can have long-term negative effects on pain. We found the treatment was contributing to the problem." Linda Watkins elaborated on the study,
“The initial pain signals to the spinal cord and the subsequent morphine-induced treatment is a two-hit process . . . you might get away with the first slap, but not the second. This one-two hit causes the glial cells to explode into action, making pain neurons go wild.
The implications for people taking opioids like morphine, oxycodone and methadone are great, since we show the short-term decision to take such opioids can have devastating consequences of making pain worse and longer lasting. This is a very ugly side to opioids that had not been recognized before."
Just now—as I was sitting in a coffee shop writing this blog post—an acquaintance of mine, whom I hadn't seen in awhile, sat down next to me and asked what I was working on. I told him about the new CU-Boulder opioid study that was released this afternoon. Out of the blue, he confessed to me that ever since back surgery two years ago, he's been battling opioid addiction. Last winter, he accidentally overdosed and almost died. Clearly, as Prince's recent death and other statistics show us, he is not alone.
In the past decade, deaths caused by drug overdoses have jumped in almost every county in the United States. In 2014, the number of deaths in the United States from opioid drugs or heroin overdoses totaled 47,055 people. This adds up to about 125 Americans every day. The death rate from drug overdoses jumped to 15 per 100,000 in 2014 from nine per 100,000 in 2003.
According to a March 2016 study by the CDC, among those who died from prescription opiate overdose between 1999 and 2013, most were ages 25 to 54. This age group also had the highest overdose rates compared to all other age groups. Drug overdoses now cause more deaths than car crashes. Opioids, such as OxyContin and other pain medications, kill way too many people every day.
One of the only optimistic aspects of the recent study from CU-Boulder is that future research could lead to medications which break the vicious cycle that causes opioids to increase and prolong chronic pain. The researchers have found ways to block specific receptors on glial cells that respond to opioids and might be able to prevent these cells from kicking into overdrive with targeted pharmaceutical interventions.
For anyone who currently requires opioids for pain management, future medications might be able to optimize opioid-based pain relief without potentially increasing and prolonging your chronic pain... but more research is needed. Stay tuned!
To read more on this topic, check out my Psychology Today blog posts,
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