Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a complex, multisystem, long-term health condition that affects people of all ages and backgrounds and can have a profound and lasting impact on daily function and quality of life.
ME/CFS is a ‘syndromic’ condition, which means that diagnosis is based on identifying a specific pattern of symptoms while ensuring that symptoms are not due to an alternative cause. Syndromic labels are used when we recognise a common pattern of symptoms but don’t yet have the investigative tools or clinical knowledge to clearly identify the underlying pathology. By giving a condition an identity, research is facilitated, and specialist services and guidance on management can be developed while waiting for advancements in diagnosis and treatment.
Diagnostic challenges in ME/CFS
Making a diagnosis of ME/CFS is complex as ME/CFS is a condition which causes symptoms in any part of the body. As no investigations can currently be used reliably in clinical practice, the diagnosis relies solely on a detailed history taken by a clinician with a good understanding of the condition and awareness of how other illnesses may contribute to symptoms. Healthcare systems are typically divided into specialist departments focusing on one organ or physiological system. ME/CFS does not belong to any medical speciality. This leads to challenges in providing specialist services, hinders the progress of clinical research and has a negative impact on education and the dissemination of advancements. Currently, most people with ME/CFS wait years before having a diagnosis confirmed by an ME/CFS specialist. In many parts of the UK and other countries, patients have no access to a specialist service, so they remain undiagnosed or misdiagnosed.
There are many different diagnostic criteria that different organisations in different countries have developed, (1,2) which adds further complexity and confounds any research that is conducted. It is also likely there are multiple pathological processes that give rise to the symptoms of ME/CFS, and the route into the illness can be multifactorial. Factors that can contribute to the development of ME/CFS include infection, e.g. Epstein Barr (Glandular fever/Mononucleosis) and COVID, major life events such as bereavement or emotional trauma, operations, pregnancy, or a combination of events. Additionally, ME/CFS is associated with other conditions, including fibromyalgia, neurodiversity, joint hypermobility, postural tachycardia syndrome, migraine, irritable bowel syndrome, endometriosis, metabolic fatty liver disease, puberty and menopause.
Symptoms of ME/CFS
By its nature, ME/CFS is a constantly fluctuating condition with Post Exertional Malaise (also referred to as Post Exertion Symptom Exacerbation (PESE)) as the core feature. Other cardinal features include debilitating fatigue worsened by activity, unrefreshing/disturbed sleep, and cognitive difficulties, often described as ‘brain fog’ (NICE 2021). (3) Symptom changes can be triggered by different types of daily activities, including physical tasks, cognitive tasks, emotional demands, social activity and orthostatic demand (physiological demand of gravity when in an upright position). Research is more straightforward to conduct when you can control as many variables as possible. The multisystemic and dynamic nature of ME/CFS means standard research processes are often unsuitable or lead to mixed results without conclusive answers.
Future research will need to look in many directions. Autonomic nervous system research is promising as it has helped demonstrate the abnormalities that occur with circulation responses in the body, particularly abnormalities in cerebral blood flow. Two-day cardiopulmonary exercise tests have shown the abnormal physiological response to physical exercise. Still, the nature of the test can precipitate an escalation in the severity of the condition, so we need to explore ways to bring these research advancements safely and effectively into the clinical setting. We may also see progress with some blood biomarkers from the fields of metabolomics, immunology and genetics.
Currently, we support people with ME/CFS through several interventions. Education about abnormal physiological processes and how symptom fluctuations relate to everyday activities is key. Pacing every aspect of daily life is a core management strategy but is challenging to do in practice. Recognising the triggers of physiological dysregulation and using behavioural strategies that support more stable physiological functions can help bring a degree of stability. For some, this can lead to improvement in function. However, most people living with ME/CFS have to manage their condition long-term, and people who are severely affected by ME/CFS are completely bedbound and dependent on the care of others.
