Latest Research: post-exertional malaise & more
November 07, 2018
Trigger warning: this post features content of a sensitive nature regarding suicide.
Supporting you to stay informed about M.E. research, we publish regular round-ups from Action for M.E. volunteer and pharmacist Emily Beardall, covering a selection of papers published in peer-reviewed journals.
Please note this is not an exhaustive list – we have selected to highlight the studies that we think 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 17 May 2018 and 30 September 2018. In each case, we have used the same name for the illness as the researchers publishing the paper.
Quality of sleep
A Spanish study in the Journal of Sleep Research looked at a link between sleep quality and quality of life in patients with CFS/M.E. Almost 1,500 CFS/M.E. patients kept a sleep diary for a month, following which they participated in questionnaires assessing fatigue, pain, ability to perform daily activities, physical and mental functioning and quality of life. High scores were recorded for pain and fatigue, and low scores for functioning and quality of life and this related to low quality of sleep.
There are several ways of defining M.E./CFS by symptoms, and finding a universally agreed definition of the illness for selecting participants in studies will help research to move forwards to find treatments. A study in the Journal of Health Psychology compared the results of the many previous studies that have attempted to find what distinguishes people with the illness from healthy controls. Post-exertional malaise, or “payback” after exertion, was found to be the most consistent defining feature of the illness, suggesting that this symptom should be considered the cardinal symptom of M.E./CFS.
Autonomic nervous system abnormalities
The autonomic nervous system controls and regulates bodily functions that we don’t have to think about, such as heart rate, circulation, digestion, and breathing. Several recent studies have looked at the autonomic nervous system abnormalities seen in people with M.E./CFS.
A study published in PLoS One could explain the cold hands and feet some people with the illness experience. The study explored the circadian rhythm, or internal body clock, and also skin temperature in ten people with M.E./CFS compared with ten healthy controls. Results were collected in winter and again in summer. Participants also gave scores for symptoms such as fatigue, sleep quality and autonomic function. Results showed that the participants with M.E./CFS had an altered 24-hour sleep-wake cycle compared with the controls, and that this related to skin temperature, indicating an abnormality in the autonomic nervous system’s regulation of body temperature by blood circulation to the extremities.
A study published in Brain Imaging and Behaviour looked at blood flow in the brain in people with CFS compared with healthy controls, and whether this relates to fatigue and variation in the time interval between heartbeats, which has previously been found to be abnormal in CFS. The authors found that fatigue severity was linked to lower variability of both blood flow in the brain and of heart rate, and suggest these findings could be future targets for treatment to alleviate symptoms.
Another study looking at autonomic control of heart rate was published in the journal Fatigue. Nine CFS patients underwent a MIGB scan, which involves injecting a dye that shows activity of nerves controlling heart muscle, along with measurement of heart rate and blood pressure variability, to find the balance between sympathetic (speeding up) and parasympathetic (slowing down) control of heart rate. Results of the study showed that autonomic impairment seen in CFS patients might be related to abnormalities in sympathetic control of heart rate, and over time this may lead to cardiac denervation, or loss of nerve control. This could account for the autonomic symptoms of CFS such as low blood pressure on standing, and could be a target for treatment.
Natural killer cells and the immune system
A study in Molecular Medicine takes research into the immune system defects in M.E./CFS a step further. Natural killer cells (NK cells) are a type of white blood cell in the immune system that attacks virus-infected cells. Studies by the same researchers have previously shown that NK cells have reduced activity in people with M.E./CFS. They have also found that the number of channels in the membrane of these cells, known as TRPM3 channels, which normally allow calcium to enter the cells, are significantly reduced in M.E./CFS patients compared with healthy controls.
This new study confirms these findings, but in addition shows that these channels are faulty in NK cells, leading to low calcium levels in the cells. As TRMP3 channels are also found throughout the body (for example in the brain, eyes, cardiovascular system, gastrointestinal system and pancreas), and as calcium is important for so many cell processes, the researchers suggest this could be a widespread impairment accounting for the diverse symptoms of M.E./CFS. Although more research is needed to confirm this, it is an exciting finding as TRPM3 channels and calcium signalling could be new targets for treatment.
A study in the journal Experimental Brain Research looked at two different ways artificial intelligence could successfully diagnose CFS. The participants underwent MRI brain scans, and scored several CFS symptoms on a scale. Computer analysis of the brain scans (based on differences in brain structure and function found in previous research) got the diagnosis right in 80% of the participants, whereas machine-learnt analysis of self-reported symptom scales was 96% correct. Although this was a small study, it perhaps shows that computers could be employed to diagnose CFS in the future.
A blood test to help diagnose M.E./CFS could be closer than ever thanks to a study published in the journal Scientific Reports which has identified a distinct pattern of metabolites, or chemical by-products of bodily processes such as energy production, in the blood of people with M.E./CFS. Blood samples were taken from 50 people with M.E./CFS and 50 healthy controls, and 562 metabolites were found to have altered blood levels in the people with M.E./CFS. Although this is a small study, combining this data with that from an earlier microbiome study, the researchers report they can predict whether or not someone has M.E./CFS with 84% confidence.
Impact of M.E. on mental health
Physical illness is a well-documented risk factor for suicide, and research has shown an increased suicide rate in patients with M.E. and CFS. Depression has been assumed to be the explanation, but authors of a study in the Journal of Health Psychology previously found that 40% of patients with the illness have suicidal feelings and a fifth of these patients did not meet the criteria for depression, concluding there are other factors leading to suicidal feelings.
The current study explores these factors further, and finds there are two main themes: loss of self, loss of others, stigma and conflict; and feeling trapped. Participants emphasised that they felt trapped by their illness, and felt hopeless due to the lack of treatments available.
Emily says: “I was relieved when I saw this research as I’m obviously not alone in having periods where I’ve felt there’s no way out and no hope for the future. The only solution seemed to be to take my own life; however, I knew I wasn’t depressed as it felt very different from episodes of depression I’d had in the past, and so I couldn’t understand why I felt like this. Even though we may not want to act on the feelings, feeling suicidal is still extremely distressing, and we need to reach out for support. Ultimately of course, we need treatments, and fast. Following the research gives me hope, as we are getting there, though not quickly enough.”
If you are experiencing suicidal feelings or emotional distress, please consider reaching out to The Samaritans for support. They are open 24 hours a day, and you can call for free on 116 123 or send them an email.