Highlights
- Changes were detected in the hippocampus area of the brain of ME/CFS patients
- These changes were associated with fatigue, pain and physical function
- They were greater in patients identified using the ICC rather than the Fukuda criteria
Background
A recent paper from researchers at Griffith University in Queensland, Australia suggests that some symptoms of ME/CFS such as fatigue, pain and sleep disturbance may be linked to structural changes in a part of the brain called the hippocampus.
The researchers include Dr Leighton Barnden who is currently also looking at brain-stem dysfunction in ME/CFS as part of a study funded by ME Research UK.
The hippocampus is a complex structure deep in the temporal lobe of the brain, and is involved in cognition, memory and regulation of the hypothalamus (which controls autonomic nervous function).
The Australian study included 25 people with ME/CFS who met only the Fukuda diagnostic criteria, 18 ME/CFS patients meeting the stricter International Consensus Criteria (ICC), and 25 healthy control subjects.
What did they find?
Using a technique called magnetic resonance imaging (MRI) to investigate the structure of the brain, the researchers found that the volumes of specific areas of the hippocampus were greater in ME/CFS patients who met the ICC criteria than in healthy controls. This was not the case in patients who met only the Fukuda criteria.
The team also looked at associations between these volume changes and the symptoms of ME/CFS. There was a mixed picture, with either increases or decreases in the size of different areas of the hippocampus being associated with fatigue, pain, sleep disturbance or physical function.
Although these associations were found across both groups of patients, they were stronger in those who met the ICC criteria for ME/CFS.
What does this mean?
Overall, the researchers suggest that their findings confirm the involvement of the hippocampus in some of the symptoms of ME/CFS patients who meet the ICC criteria, including ‘brain fog’, memory problems and the ability to do complex tasks.
The hippocampus is a vulnerable structure that can be damaged a number of ways, and alterations in hippocampal networks have been reported in conditions such as chronic stress, Cushing’s disease, dementia and Alzheimer’s disease.
The Queensland group suggest that the increases they detected in the hippocampus may be due to the brain adapting to changes in the brain stem (which they reported in an earlier study), in order to maintain communication between these two areas of the brain.
The study was relatively small in terms of patient numbers, which is often the case with a technique as expensive as MRI. So it needs to be replicated on a larger scale to confirm the findings.
However, the study does add to our growing recognition of the impact of ME/CFS on the brain, marking out ME/CFS as a discrete neurological disease. It also raises questions about what types of patient are captured by different diagnostic criteria.
If these results can be confirmed by larger studies, perhaps we might see MRI scans used to detect ME/CFS, and doctors able to offer treatment with off-the-shelf or novel drugs.
