Reprinted with kind permission from ME Research, Breakthrough Magazine, Autumn 2013
One of the key difficulties facing ME/CFS patients is standing, especially standing still, which can bring on symptoms such as dizziness, altered vision, nausea and fatigue. So it is certainly possible that some dysfunction of the autonomic nervous system is involved in the disease.
Since 2006, with the financial help of ME Research UK, Professor Julia Newton and her team at the School of Clinical Medical Sciences, University of Newcastle have been investigating autonomic nervous system function in ME/CFS. In fact, their scientific papers have reported autonomic dysfunction in three-quarters of ME/CFS patients, and that their blood pressure is lower and its regulation abnormal compared with healthy people.
A new scientific paper from Prof Newton’s group (published this year in the Journal of Internal Medicine) describes postural orthostatic tachycardia syndrome (POTS), an aspect of autonomic dysfunctionthat can produce substantial disability among otherwise healthy people. POTS is defined as symptoms of orthostatic intolerance (problems with standing), and it is easily diagnosed by observing the increase in heart rate on moving from lying to standing (a person with POTS has an abnormally large increase).
The team wanted to test a large group of ME/CFS patients for the presence of POTS, and to look for clinical differences between those with and without the disorder. If differences exist, it might be possible to treat and manage POTS patients as a distinct clinical subtype of ME/CFS, since we already know that this diagnosis includes a wide range of different kinds of patients.
In total, 179 consecutive patients from the Newcastle CFS Clinical Service were examined, and they underwent a series of demographic and symptom assessments, as well as autonomic function tests including heart rate variability (HRV) and left ventricular ejection time of the heart. The patients had been ill for just over 7 years on average and, overall, the prevalence of daytime sleepiness and orthostatic symptoms was high, as was physical and cognitive impairment.
In total, 24 patients (13%) had POTS, and they were younger (average age 29), less fatigued, less depressed, and reported less daytime sleepiness than the 155 (87%) without POTS. Crucially, they also had greater orthostatic symptoms and autonomic dysfunction. In fact, it was possible to predict which patients would be in the POTS group with 100% accuracy from a combination of high orthostatic intolerance and low daytime sleepiness. Of particular interest was the significantly lower HRV in the patients with POTS, indicating a greater level of autonomic nervous dysfunction in this subgroup.
These interesting results were the subject of an expert commentary in the same issue of the Journal of Internal Medicine by Prof. Jo Nijs and colleagues from Brussels. They point out that the investigation provides compelling data for a novel subgroup within the ME/CFS population, and that the results support the view of ME/CFS as a central nervous system disorder.
Clearly, it is important that POTS be recognised and managed, whether in ME/CFS or other groups of patients,since treatment can improve functional impairment and quality of life.
ME Research UK commissions and funds scientific (biomedical) investigation into the causes, consequences and treatment of ME/CFS, a debilitating illness which affects around 200,000 people in the UK and 1 million in the USA but is neither well understood nor, in many cases, properly recognised. To date, the charity has awarded more than £1 million to universities in the UK and overseas for 35 distinct scientific studies into ME/CFS, resulting in the publication of over 50 research papers.