A growing body of evidence suggests that a subtype of chronic pain called nociplastic pain may be associated with unhealthy emotional regulation – particularly anger – according to a recent review.
IASP Chronic Pain Subtypes
The International Association for the Study of Pain (IASP), in a 2020 review article in the journal Pain, proposed three subtypes of chronic pain, although these categories can be challenging to assess, wrote Brandon C. Yarns, MD, of the VA Greater Los Angeles Healthcare System, and colleagues in a recent review.¹
Nociceptive pain is characterized by ongoing injury to peripheral tissues, such as pain associated with osteoarthritis, rheumatoid arthritis, cancer pain, and other conditions.
Neuropathic pain is characterized by ongoing injury to peripheral nerves, such as pain associated with diabetic neuropathy.
Nociplastic pain, by contrast, “includes conditions without evidence of peripheral tissue or nervous system lesion or disease, or with poor correlation of such peripheral findings to the patient’s subjective report of the locations of pain.” This type of pain is often associated with conditions such as nonspecific chronic low back pain, fibromyalgia, irritable bowel syndrome, and tension headaches, the researchers wrote.
Anger Regulation in Nociplastic Pain Syndromes
The literature describing how emotion regulation, especially anger regulation, affects the presence and severity of nociplastic pain conditions goes back decades, Dr. Yarns told PPM. However, no prior reviews included neural correlates of emotion regulation in chronic pain patients. “So, we thought it was important to try to bring together the behavioral and correlational research on anger and anger regulation in chronic pain with brain imaging research on emotion regulation, most of which was in healthy adults,” with the goal of developing a model and an agenda to simulate further research in nociplastic pain, he explained.
Proposed Biobehavioral Model Links Anger and Pain at Brain Level
In an review published in Neuroscience & Biobehavioral Reviews, Dr. Yarns’ team summarized the latest evidence and propose a unified, biobehavioral model – the Anger, Brain, and Nociplastic Pain (AB-NP) Model – as a way to advance research and inform treatments for chronic pain and its common comorbidities.
The team noted that the distinctions between nociplastic pain and other chronic pain subtypes start at the level of neural activity. Previous research has shown that nociplastic pain conditions are associated with neural activation patterns in emotional brain regions only, compared to activation in both sensory and affective regions observed in other chronic pain subtypes. For instance, task-based functional MRI studies have shown that periods of high spontaneous pain compared to low pain were only associated with increased activation in the rostral anterior cingulate cortex (rACC), medial prefrontal cortex (mPFC), amygdala, and ventral striatum in people with chronic low back pain.¹
Next, the researchers highlighted findings from emotion research suggesting that nociplastic pain is associated with higher rates of secondary emotions, such as shame or embarrassment. “Considerable controversy remains about whether discrete emotions – such as anger – are associated with activations of unique and specific neural networks or whether most or all emotions activate the same or similar neural networks,” they wrote. However, studies have demonstrated that improved anger regulation can reduce pain.¹
Pain Psychology: Gaps and Emerging Approaches
Emotional Awareness and Expression Therapy
“Novel psychotherapies for chronic pain that act on emotion regulation – in particular anger regulation – have produced large reductions in chronic pain in clinical trials, namely emotional awareness and expression therapy (EAET),” Dr. Yarns explained. These therapies purport to act on brain circuits dealing with emotion and emotion regulation, but so far this association has not been tested, he added.
Dr. Yarns said he was surprised to find that no prior study had evaluated an anger regulation task in people with chronic pain during a brain scan. “This was surprising because there is so much behavioral and correlational data on the importance of anger regulation in chronic pain, so we thought someone would have evaluated neural correlates, but that is not what we found,” he said.
Anger, Brain, and Nociplastic Pain (AB-NP) Model
The AB-NP model, according to Dr. Yarns and coauthors, “illustrates the inverse relationship between nociplastic pain and anger in the brain” The model shows how increases in unhealthy anger suppression and expression are associated with increased nociplastic pain, as well as activation in the amygdala and mPFC. However, increased anger awareness reduces nociplastic pain in treatment studies and reduces amygdala and mPFC activation in imaging studies of pain-free adults.
The review was limited by several factors including the heterogenous terminology used in the studies, which made synthesis of the studies a challenge, the researchers noted. Other limitations included the incomplete imaging data and lack of data on testing the paradigms for inducing anger, noted the authors.
Anger As a Pain Treatment Target
According to Dr. Yarns, the key takeaway from his team’s review is the illustration that anger regulation is clearly an important treatment target for nociplastic pain conditions.
“Specifically, when a pain patient gets angry, becoming aware of the feeling and allowing it to pass without immediately acting on it and without undue distress – anger awareness – could reduce pain by opposing the brain circuits involved in the generation and maintenance of many forms of chronic pain,” he said. “The fact that it teaches this form of anger awareness could be one way that EAET is so effective to reduce or even eliminate chronic pain,” he added.
As for adopting the model in clinical practice, “I think the biggest barrier is skepticism by both patients and providers about how important the brain, emotions, and emotion regulation are to most forms of chronic pain,” Dr. Yarns told PPM. “Since patients feel chronic pain in their bodies, most assume something is wrong with their bodies, but that is not always the case,” he said. “Emotional brain circuits affect the experience of all pain, and brain imaging research shows that changes in these circuits may cause nociplastic pain,” he emphasized. “Therefore, treatments for these conditions should intervene on the levels of emotion and the brain more than the body, which is where the pain is often felt, but not always where it is caused,” he explained.
“Pain management providers also frequently focus on body-based treatments such as injections, devices, and physical therapy, and most psychological/brain-based treatments only focus on coping with or accepting the pain,” said Dr. Yarns. However, “our review suggests that at least one emotional process – anger awareness – could directly oppose the brain circuits that generate and maintain nociplastic chronic pain, and therefore reduce it,” he said.
Disclosures: The study received no outside funding. Dr. Yarns and a coauthor were supported by the US Department of Veterans Affairs.
- Yarns BC, Cassidy JT, Jimenez AM. At the intersection of anger, chronic pain, and the brain: A mini-review. Neurosci Biobehav Rev. 2022 Apr;135:104558. doi: 10.1016/j.neubiorev.2022.104558. Epub 2022 Feb 2.