Studies reveal that chronic primary pain is associated with measurable structural changes in the folds of the cerebral cortex. However, the brain's inherent neuroplasticity provides hope that these anatomical alterations could adapt and reverse through comprehensive pain management.
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Scientific Frontline: Extended "At a Glance" Summary: Chronic Primary Pain and the Brain
The Core Concept: Chronic primary pain—such as fibromyalgia—is persistent pain not fully explained by clear triggers like injury or illness, and recent research indicates it is associated with structural changes in the cerebral cortex.
Key Distinction/Mechanism: Unlike acute pain, which is an immediate response to injury, chronic primary pain involves alterations in the folds and grooves of the cerebral cortex, specifically in areas related to processing emotions, memories, sensory perceptions, and pain assessment.
Major Frameworks/Components:
- Cortical Folding Differences: Individuals with chronic primary pain exhibit more pronounced folding in a region at the front of the left hemisphere associated with emotion and memory processing.
- Shallower Cortical Grooves: In the right hemisphere, shallower grooves were observed in anterior regions linked to processing sensory perceptions and pain.
- The Role of Emotion and Cognition: The anatomical changes support the hypothesis that as pain becomes chronic, emotional and cognitive processes become increasingly dominant, potentially creating a feedback loop involving stress, negative emotions, and pain signaling.
- Neuroplasticity: The structural differences are viewed as snapshots; the brain's adaptability (neuroplasticity) suggests that successful multimodal pain management might reverse these changes, meaning chronic pain is not necessarily a permanent condition.
Branch of Science: Neuroscience, Neurology, Psychology
Future Application: The findings emphasize the necessity of multimodal pain management (incorporating medication, physiotherapy, behavioral therapy, and education) and highlight the need for longitudinal studies to determine if targeted therapies can normalize cortical structure and alleviate symptoms.
Why It Matters: Validating the physical manifestations of chronic primary pain provides reassurance to patients whose symptoms are often dismissed and directs clinical treatment toward comprehensive strategies that address the intertwined neurological and psychological components of the condition.
Persistent pain often has no clear cause. However, studies show measurable differences in the structure and activity of the brains of those affected. This might explain why they experience chronic pain.
"Many of our study participants were grateful that someone was taking their symptoms seriously and conducting research into them," says neuroscientist Salome Häuselmann. Her study, funded by the SNSF, investigated how the brains of people with chronic pain differ from those of healthy control subjects.
The project focused on what is known as "chronic primary pain"—a term used to describe chronic pain conditions that cannot be fully explained by identifiable triggers such as an injury or illness. A typical example of this is fibromyalgia, from which two-thirds of the study participants suffered. It is characterized by persistent pain throughout the body and can lead to severe fatigue and a significant reduction in quality of life. However, long-lasting symptoms can also occur in specific parts of the body, such as abdominal pain.
Roughly One-Fifth of People Suffer from Chronic Pain
"Most of the study participants had already been through a long, painful journey, which had taken them from their general practitioner, via various specialists, to a pain clinic, and finally to the psychosomatic department of a university hospital," says Häuselmann. On average, the participants had been struggling with their symptoms for more than thirteen years. According to a recent survey, about one in five people in Europe suffers from chronic pain.
"The exact mechanisms that cause and perpetuate chronic pain are not known," explains Häuselmann. Genetic, biological, psychological, and social factors all play a part. Multimodal pain management, therefore, aims to address all these aspects simultaneously: not just with medication, but also with physical therapy, occupational therapy, behavioral therapy, patient education about pain, and much more.
Previous studies have suggested that chronic pain is associated with changes in the brain. Häuselmann, therefore, took a closer look at the brain structure of people with chronic primary pain. To this end, she recruited patients from the Psychosomatic Medicine Unit at the Department of Neurology at Inselspital, Bern. Selma Aybek, a neurologist at the University of Fribourg, was also involved in the project.
High Complexity
The team carried out anatomical brain MRI scans on thirty people with chronic primary pain and thirty healthy individuals. The focus was on the folded cerebral cortex, which forms the outermost layer of the brain. The folds reflect the complexity of the brain, with different regions of the cortex being responsible for specific tasks, such as signal processing and cognitive processes.
Compared to healthy individuals, the cerebral cortex of those suffering from chronic primary pain exhibited a number of structural differences. In a region at the front of the left hemisphere, the cerebral cortex was more folded. This area is responsible for tasks such as processing emotions and memories. It is also linked to the perception and assessment of chronic pain.
In the right hemisphere, people with chronic primary pain showed shallower grooves in several regions, including areas in the anterior part of the brain, compared to healthy controls. These areas are linked, among other things, to the processing of sensory perceptions and to the processes involved in assessing and processing pain.
Emotions Play an Important Role
The results suggest that chronic primary pain is associated with measurable changes in the architecture of the cerebral cortex. This relates, in particular, to regions that process sensory perceptions, emotions, and cognitive processes. "This is consistent with the assumption that, as pain transitions from acute to chronic, emotional and cognitive processes also play an increasingly important role," says Häuselmann.
This could lead to a vicious cycle in which the processing of pain signals, stress, negative emotions, and cognitive assessments are interlinked and reinforce one another. Similar changes in brain structure can also be found in people experiencing other forms of distress, such as prolonged stress or trauma, which are likewise influenced by biological, psychological, and social factors.
The Brain Can Adapt
According to Häuselmann, however, the results are merely snapshots. It is, therefore, not clear whether the brain structure changes as a result of the chronic conditions, or whether those affected already have this particular anatomical structure—and are therefore more prone to chronic pain. To answer these questions, extensive longitudinal studies would be required, of which there have been very few in the field of pain research to date.
"The good news, however, is that our brains are adaptable. That gives us hope," says Häuselmann. It is possible that, in the course of successful pain management, the folds and grooves in the cerebral cortex could once again come to resemble those found in people who do not experience pain. However, whether and how such changes are linked to an improvement in symptoms still needs to be investigated. That said, "chronic pain need not be seen as a permanent condition," says Häuselmann.
Published in journal: NeuroImage: Clinical
Title: Structural brain alterations in chronic primary pain: a multimodal MRI study
Authors: Salome Häuselmann, Anna Wyss, Nina Bischoff , Rupert Bruckmaier, Josef Gross, Chantal Berna, Martin grosse Holtforth, Selma Aybek, and Nicolas Gninenko
Source/Credit: Swiss National Science Foundation
Edited by: Scientific Frontline
Reference Number: ns082926_01
