Researchers have found strong evidence that people are most likely to develop ME/CFS at two points in life, in a study that could help uncover causes of the disease and point to ways to prevent it. The study, led by researchers at the Institute of Genetics and Cancer, examined survey data from more than 9,000 people with Myalgic Encephalomyelitis or Chronic Fatigue Syndrome (ME/CFS) across ten European countries.They found an early onset peak at an average of age 16, and a later one at an average of 37 years old, with seven of the countries showing similar onset peaks individually.People with early-onset ME/CFS were more likely to report infection as a trigger, be more severely affected and have close relatives with ME/CFS.The researchers confirmed the presence of two age peaks in a separate group of more than 6,000 people with ME/CFS who took part in DecodeME, a large UK genetics study of the disease. Patient’s role in study Unusually, the study was initiated by a patient, Simon McGrath, in a social media post. Simon, who has a bioscience background and has had severe ME/CFS for 30 years, was intrigued by a 2014 study showing two peaks in the age at which people in Norway received an ME/CFS diagnosis. To me, this was one of the most striking research findings about ME/CFS, which is poorly understood. It was vital to try to replicate it in other data, because the age at which diseases start is often tied to their causes. Simon McGrath ME/CFS patient With no new study in sight, he posted a message on the social media platform X asking if anyone had data showing onset age for people with ME/CFS.The Head of the Norwegian ME Association replied to say it had exactly that data for thousands of people across Europe, leading to the collaboration that carried out the new study, involving people with ME/CFS, those close to them, and professional scientists. These findings help build a picture of who is most at risk of ME/CFS and could mean that splitting patients into early and late-onset groups in future research could make it easier to identify disease mechanisms. Audrey Ryback Postdoctoral Research Fellow, Institute of Genetics and Cancer Related links Read the paper in Oxford Open Immunology Audrey Ryback Image credit: DMP via GettyImages Tags 2026 Publication date 23 Mar, 2026
