Abstract
Myalgic Encephalomyelitis (ME), sometimes called Chronic Fatigue Syndrome (CFS), is a complex, debilitating condition characterised by symptoms such as profound fatigue, autonomic dysfunction, gastrointestinal problems, unrefreshing sleep, cognitive problems, exercise intolerance and post-exertional malaise (PEM) (a worsening of symptoms after mild physical or mental effort). The pathophysiology of ME remains poorly understood. This paper proposes a novel hypothesis centred on norepinephrine dysregulation and insulin signaling as the underlying mechanisms contributing to distinct subtypes of ME. I hypothesise that ME can be categorised into three subtypes based on variations in norepinephrine transport and insulin signaling: ME1, ME2, and ME3. In ME1, a higher than normal rate of insulin secretion during the first phase insulin response and/or hypersensitive insulin receptors leads to reduced neuronal norepinephrine reuptake, resulting in elevated extracellular norepinephrine and subsequent down-regulation of beta-2 adrenergic receptors. ME2 is characterised by prolonged insulin release and insulin resistance, which may contribute to the development of postural orthostatic tachycardia syndrome (POTS) and microclot formation. ME3 is marked by reduced norepinephrine synthesis and a resultant deficiency of norepinephrine within neurons. All three subtypes involve a deficiency of norepinephrine inside the noradrenergic neuron which is worsened by physical and mental exertion. There are many similarities between ME and Long COVID. Both have their onset after a virus and have a similar symptom profile, as well as having the same co-occurring conditions such as mast cell activation and POTS. It is quite possible that a subset of Long COVID patients have ME, and so I will be referring to both ME and Long COVID research papers throughout this hypothesis paper. This hypothesis integrates genetic, metabolic, and neuroendocrine data to delineate these subtypes and suggests tailored diagnostic and therapeutic approaches for each. This hypothesis aims to guide future research into the distinct pathophysiological mechanisms of ME and enhance understanding and management of this debilitating condition.
