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Brain activity, sub-groups and more: research round-up

March 02, 2016

Each month, Action for M.E. Volunteer Pharmacist Emily Beardall explains some of the recently published research studies on M.E.

Please note this is not an exhaustive list – we have selected to highlight the studies that are most likely to resonate with the daily lives of those affected by the condition. We will also report separately on further studies of significance, as and when they are published.

You can search online directory PubMed for most studies about M.E. published in peer-reviewed journals.

The following studies were published online between 22 January 2016 and 21 February 2016. In each case, we have used the same name for the illness as the researchers publishing the paper.

Brain activity characteristics in CFS patients 

A study in Neuropsychiatric Disease and Treatment compared the brain activity of CFS patients with that of healthy controls. Although it was a small-scale study, the results showed a clear difference both in the strength of brain activity and in the position of the activity in the brain (follow the link above to see the images). In CFS patients there was decreased brain electrical activity suggesting that the brain is in an inhibitory, or dampened down state, and that activity in the right frontal region and left occipital region was significantly different. The authors point out that this matches up with clinical features in CFS because these regions are responsible for problem-solving, decision-making, motivation and planning.

CFS symptom-based phenotypes

A large-scale study in the Journal of Psychosomatic Research set out to find sub-groups of UK CFS patients according to their symptoms and duration of illness, so that future research could determine suitable treatments. Almost all of the patients had post-exertional malaise, cognitive difficulties (such as concentration problems), and sleep problems. Six sub-groups were found based on the additional symptoms of sore throat, painful lymph nodes, flu-like illness, headache, joint pain, muscle pain, dizziness, nausea, and palpitations. Each of these sub-groups could be further sub-divided into categories of comorbid conditions, such as IBS, migraine, anxiety and depression. These sub-groups were then shown to also exist in a cohort of Dutch CFS patients.

The six sub-groups were:

  • Class 1: No additional symptoms (oligosymptomatic)
  • Class 2: All additional symptoms except painful lymph nodes and sore throat
  • Class 3: Muscle or joint pain only
  • Class 4: Sore throat, painful lymph nodes, headache and flu-like symptoms
  • Class 5: All additional symptoms except dizziness, nausea and palpitations
  • Class 6: All additional symptoms (polysymptomatic).

Genetic variations in subjects M.E./CFS
A Genome-wide association study (GWAS) in Translational Psychiatry compared the DNA of M.E./CFS patients with that of healthy controls to see if there are any differences which could give clues to the underlying causes of the illness, along with a possible genetic predisposition. Several differences were found in the regions which code for components of the immune system, such as T-cell receptors, indicating a possible predisposition to autoimmunity and susceptibility to viral infections. In addition, differences in the genes coding for glutamate receptors in the brain were found. Glutamate is a neurotransmitter which is important for memory formation, learning, and regulation of the body’s systems. Problems with the receptors for glutamate are implicated in many other neurological illnesses, such as chronic pain and MS.

Although this was a relatively small-scale study (42 cases with a confirmed diagnosis of M.E./CFS and 38 healthy controls), this shows that GWAS is promising for advancing M.E./CFS research by defining sub-groups based on genetic findings.

Mitochondrial DNA variants
Rather than looking at our DNA as with the study above, this study in the Journal of Translational Medicine examined the DNA of mitochondria, which are present in every cell in the human body and are responsible for energy production and for producing some of the body’s hormones, and several other important functions. Although no known disease-causing mitochondrial DNA mutations were found in the M.E./CFS patients, genetic variants were found which link closely to certain neurological, inflammatory, and digestive system symptoms in the M.E./CFS patients, which suggests that the mitochondrial DNA of an individual with M.E./CFS can affect the type and severity of particular symptoms.