Schweizerischer Nationalfonds / Fonds national suisse
Chronic pain is reflected in the folds and grooves of the cerebral cortex
Bern (ots)
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 characterised 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 GP, 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 13 years. According to a recent survey, around one in five people in Europe suffer 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. So-called multimodal pain management therefore aims to address all these aspects simultaneously: not just with medication, but also with physiotherapy and occupational therapy, behavioural therapy, educating patients 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 30 people with chronic primary pain and 30 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 or cognitive processes.
Compared with 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 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 and emotions, as well as 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 circle 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.
The text of this news and further information are available on the website of the Swiss National Science Foundation.
Contact:
Salome Häuselmann
Psychosomatic Medicine
Department of Neurology
Inselspital Bern
Phone: +41 31 308 23 87
Email: salome.haeuselmann@gmail.com