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In chronic pain, catastrophizing tied to disrupted circuitry.

REPORTING FROM APS 2019

MILWAUKEE -- When a patient with acute pain tumbles into a chronic pain state, many factors are at play, according to the widely accepted biopsychosocial theory of pain. Emotional, cognitive, and environmental components all contribute to the persistent and recalcitrant symptoms chronic pain patients experience.

Now, modern neuroimaging techniques show how, for some, pain signals hijack the brain's regulatory networks, allowing rumination and catastrophizing to intrude on the exteroception that's critical to how humans interact with one another and the world. Interrupting catastrophizing with nonpharmacologic techniques yields measurable improvements --and there's promise that a single treatment session can make a lasting difference.

"Psychosocial phenotypes, such as catastrophizing, are part of a complex biopsychosocial web of contributors to chronic pain. Catastrophizing almost certainly acts via a variety of pathways, and it seems to be a really important factor to measure, both for pharmacologic and nonpharmacologic treatment," said Robert R. Edwards, PhD, a psychologist at Brigham and Women's Hospital/Harvard Medical School (Boston) Pain Management Center. Dr. Edwards moderated a session focused on catastrophizing at the scientific meeting of the American Pain Society.

MRI shows brain connectivity

Through magnetic resonance imaging techniques that measure functional connectivity, researchers can now see how nodes in the brain form connected networks that are differentially activated.

For example, the brain's salience network (SLN) responds to stimuli that merit attention, such as evoked or clinical pain, Vitaly Napadow, PhD, said during his presentation. Key nodes in the SLN include the anterior cingulate cortex, the anterior insula, and the anterior temporoparietal junction. One function of the salience network, he said, is to regulate switching between the default mode network (DMN)--an interoceptive network --and the central executive network, usually active in exteroceptive tasks.

"The default mode network has been found to play an important role in pain processing," Dr. Napadow said. These brain regions are more active in self-referential cognition thinking about oneself--than when performing external tasks, he said. Consistently, studies have found decreased DMN deactivation in patients with chronic pain; essentially, the constant low hum of pain-focused DMN activity never turns off in a chronic pain state.

For patients with chronic pain, high levels of catastrophizing mean greater impact on functional brain connectivity, said Dr. Napadow, director of the Center for Integrative Pain Neuroimaging at the Martino Center for Biomedical Imaging at Massachusetts General Hospital and Harvard Medical School, Boston.

Looking at patients with chronic low back pain, he and his research team looked for connections between the DMN and the insula, which has a central role in pain processing. This connectivity was increased only in patients with high catastrophizing scores, said Dr. Napadow, with increased DMN-insula connectivity associated with increased pain scores only for this subgroup (Pain. 2019 Mar 4. doi: 10.1097/j.pain.0000000000001541).

"The model that we're moving toward is that chronic pain leads to a blurring in the canonical network" of brain connectivity, Dr. Napadow said. "The speculation here is that the DMN-SLN linkage could be a sort of neural substrate for a common perception that chronic pain patients have--that their pain becomes part of who they are. Their interoceptive state becomes linked to the pain they are feeling: They are their pain."

Where to turn with this information, which has large clinical implications? "Catastrophizing is a consistent risk factor for poor pain treatment outcomes, especially when we're talking about pharmacologic treatments," Dr. Edwards said. Also, chronic pain patients with the highest catastrophizing scores have the most opioid-related side effects, he said.

CBT affects risk

"Cognitive-behavioral therapy is potentially the most effective at reducing this risk factor," said Dr. Edwards, noting that long-term effects were seen at 6 and 12 months post treatment. "These are significant, moderate-sized effects; there is some evidence that effects are largest in those with the highest baseline pain catastrophizing scores."

"CBT is considered the gold standard, mainly because it's the best studied" among treatment modalities, psychologist Beth Darnall, PhD, pointed out in her presentation. There's evidence that other nonpharmacologic interventions can reduce catastrophizing: Psychology-informed yoga practices, physical therapy, and certain medical devices, such as high-frequency transcutaneous electric nerve stimulation units, may all have efficacy against catastrophizing and the downward spiral of chronic pain.

Still, a randomized controlled trial of CBT for pain in patients with fibromyalgia showed that the benefit, measured as reduction in pain interference with daily functioning, was almost twice as high in the high-catastrophizing group, "suggesting the potential utility of this method for patients at greatest risk," said Dr. Edwards.

"We see a specific pattern of alterations in chronic pain similar to that seen in anxiety disorder; this suggests that some individuals are primed for the experience of pain," said Dr. Darnall, clinical professor of anesthesiology, perioperative medicine, and pain medicine at Stanford (Calif.) University. "We are not born with the understanding of how to modulate pain and the distress it causes us."

When she talks to patients, Dr. Darnall said: "I describe pain as being our 'harm alarm.' ... I like to describe it to people that 'you have a very protective nervous system."'

Dr. Darnall and her colleagues reported success with a pilot study of a single 2.5-hour-long session that addressed pain catastrophizing. From a baseline score of 26.1 on the Pain Catastrophizing Scale to a score of 13.8 at week 4, the 57 participants saw a significant decrease in mean scores on the scale (d [effect size] = 1.15).

On the strength of these early findings, Dr. Darnall and her collaborators are embarking on a randomized controlled trial; the three-arm comparative effectiveness study will compare a single-session intervention against 8 weeks of CBT or education-only classes for individuals with catastrophizing and chronic pain. The trial is structured to test the hypothesis that the single-session intervention will be noninferior to the full 8 weeks of CBT, Dr. Darnall said.

Building on the importance of avoiding stigmatizing and pejorative terms when talking about pain and catastrophizing, Dr. Darnall said she's moved away from using the term "catastrophizing" in patient interactions. The one-session intervention is called "Empowered Relief--Train Your Brain Away From Pain."

There's a practical promise to a single-session class: Dr. Darnall has taught up to 85 patients at once, she said, adding, "This is a low-cost and scalable intervention."

Dr. Edwards and Dr. Napadow reported funding from the National Institutes of Health, and they reported no conflicts of interest. Dr. Darnall reported funding from the NIH and the Patient-Centered Outcomes Research Institute. She serves on the scientific advisory board of Axial Healthcare and has several commercial publications about pain.

BY KARI OAKES

koakes@mdedge.com

Caption: Patients with the most opioid-related side effects have the highest catastrophizing scores, Dr. Robert R. Edwards said.

Caption: Chronic pain patients' interoceptive state becomes linked to the pain they are feeling, said Dr. Vitaly Napadow.

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Title Annotation:PAIN MEDICINE
Author:Oakes, Kari
Publication:Clinical Psychiatry News
Date:May 1, 2019
Words:1145
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