Chronic pain lives in the brain

When we think about chronic pain, chances are we think of an afflicted body part: an aching lower back, unbearably stiff finger joints, or a throbbing shoulder. But to effectively treat chronic pain, new research says we should be looking to the brain instead of the body.

What is Chronic Pain?

Chronic pain is defined as pain lasting 12 weeks or more, but this definition might be oversimplifying the problem. That is because chronic pain lives on an entirely different scale from your typical “I stubbed my toe” 1-10 pain chart. Chronic pain is more than just a symptom. It’s a debilitating issue that slowly seeps into every aspect of life, preventing you from getting a full night’s sleep, keeping you home from work, and making it a challenge to complete even the simplest daily activities.

Experts estimate that over one hundred million Americas suffer from chronic pain 1. That’s almost a third of the country. And for many people living with chronic pain, even the strongest drugs can fail to damper discomfort. Not to mention that prescription pain killers can come with serious side effects, are addictive, can make pain worse in the long run, and are all too easy to accidentally overdose on.

Despite the toll chronic pain takes, it has not always been well understood. Historically, doctors have focused on treating the physical cause of the pain, assuring patients that relief would come once the injury or disease was cured. But this is often an ineffective approach, and many patients may even be told the pain is all in their head.

Now, though, researchers are starting to rethink the root causes of chronic pain. Rather than seeing it as a lingering version of acute pain, they have begun to recognize it as a complex nervous system disorder that changes the brain’s structure, chemistry, and activity.

How Does Chronic Pain Affect the Brain?

In a way, chronic pain really is “all in the head” – most chronic pain conditions cause literal changes in the brain that reinforce the pain cycle. Neuroscientists call this the “centralization of pain”. It means that pain itself modifies the way the central nervous system works, so that a patient actually becomes more sensitive and experiences more pain with less provocation…

  • Chronic pain changes your brain’s structure. Neuroimaging studies have shown that chronic pain can alter the size of certain brain regions and change the connectivity between these regions 2. The way different parts of the brain “talk” to each other becomes abnormal as a result 3. For example, chronic pain is notorious for affecting a brain region called the dorsolateral prefrontal lobe. This area is involved in cognition, motor planning, and memory. A chronic pain brain will have difficulty performing these functions normally. This explains why many patients experience fear, anxiety, or depression in conjunction with chronic pain 4. Unfortunately, all of these additionally symptoms just exacerbate the underlying pain condition.
  • Chronic pain changes your brain’s chemistry. Chronic pain stimulates the brain to generate abnormal levels of chemicals called neurotransmitters. In the right amount, these chemicals create the perfect balance of activity and inhibition so the brain reaches a “Goldilocks” level of function – not too much or too little, just the right amount. But abnormal amounts of key neurotransmitters prevent certain brain regions from “turning off” when they should. This results in a brain that is overly-sensitive to pain and a stimulates a feed-forward cycle that reinforces the chronic pain state 5.
  • Chronic pain changes your brain’s activity. Scientists have discovered that there is a difference in brain activity patterns among patients with temporary pain and those with long-lasting pain 6. Although the experience of pain feels the same in acute and chronic pain stages, the way the brain processes pain is different. Researchers found that as pain morphs from acute to chronic, the representation of pain in the brain shifts from classical pain areas to brain regions associated with emotion. This might explain why treatments that work well for acute pain patients don’t provide any relief for chronic pain patients with the same injury.

What Can You Do?

It is important to note that while these changes may seem scary or overwhelming, they are not permanent! The brain is moldable and with the right treatment strategy, it can be reprogrammed to set pain processing systems back to normal and halt the centralization of pain from progressing further 7.

If you have yet to find relief for your chronic pain, one treatment option to consider is biofeedback. It has been shown to decrease headache and migraine intensity, reduce chronic muscle pain, and alleviate pain associated with fibromyalgia 8. Other therapies like massage, mindfulness-based stress reduction, and relaxation techniques can also be helpful.

Remember that for a chronic pain treatment to be successful, you need to target the source of the problem – the brain! That means calming down your central nervous system and getting your brain back to a state of balance is the top priority.

Bibliography

1 R. L. Nahin, “Estimates of pain prevalence and severity in adults: United States, 2012,” J Pain, vol. 16, no. 8, pp. 769-80, 2015.

2 A. May, “Structural brain imaging: A window into chronic pain,” The Neuroscientist, vol. 17, no. 2, pp. 209-220, 2011.

3 P. Y. Geha, M. N. Baliki, R. N. Harden, B. W. R, T. B. Parrish and A. V. Apkarian, “The brain in chronic CRPS pain: Abnormal gray-white matter interactions in emotional and autonomic regions,” Neuron, vol. 60, no. 4, pp. 570-581, 2008.

4 D. Borsook, “A future without chronic pain: Neuroscience and clinical research,” Cerebrum, vol. May, no. 2012, p. 7, 2012.

5 V. Napadow and R. E. Harris, “What has functional connectivity and chemical neuroimaging in fibromyalgia taught us about the mechanisms and management of ‘centralized’ pain?,” Arthritis Research & Therapy, vol. 16, p. 425, 2014.

6 J. Hashmi, M. Baliki, L. Huang, A. Baria, S. Torbey, K. Hermann, T. Schnitzer and V. Apkarian, “Shape shifting pain: chronification of back pain shifts brain representation from nociceptive to emotional circuits,” Brain, vol. 136, no. 9, pp. 2751-68, 2013.

7 R. Rodriquez-Raeche, A. Niemeier, K. Ihle, W. Ruether and A. May, “Brain Gray Matter Decrease in Chronic Pain Is the Consequence and Not the Cause of Pain,” Journal of Neuroscience, vol. 29, no. 44, pp. 13746-50, 2009.

8 D. L. Frank, L. Khorshid, J. F. Kiffer, C. S. Moravec and M. G. McKee, “Biofeedback in medicine: Who, when, why, and how?,” Ment Health Fam Med, vol. 7, no. 2, pp. 85-91, 2010.

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Morgan Ingemanson is a PhD Candidate at the University of California, Irvine studying neurobiology. She specializes in functional neuroimaging and has been investigating the use of robotic devices for rehabilitating motor function after stroke. She is interested in mapping CNS repair and developing therapeutic interventions for neurorecovery.