The cause of your chronic and severe fatigue: Scientists studied the make-up of people with the illness… and now think they’ve found the genetic traits to blame

It’s more than 30 years since mainstream medicine acknowledged the existence of myalgic encephalomyelitis (ME) or chronic fatigue syndrome (CFS) – a condition characterised by debilitating fatigue, brain fog, sleeping problems, dizziness and pain.

In that time, there has been mounting scientific evidence ME/CFS – which affects more than 400,000 people in the UK – is a genuine ailment rooted in physical causes that can lead to a wide array of symptoms.

Yet arguments have continued to rage over whether it’s a ‘real’ illness (in the 1980s it was dubbed ‘yuppie flu’ as it seemed to mainly affect young professionals) or ‘all in the mind’.

That scepticism is partly due to the variety of non-specific symptoms associated with the condition.

But now scientists at the University of East Anglia have uncovered some of the strongest evidence yet that CFS is a physiological – rather than psychological – illness that may be due to changes in someone’s DNA.

What’s more, they claim those changes might also explain chronic fatigue symptoms seen in at least four other common diseases – long Covid (which affects between 1.8 million and two million people), multiple sclerosis (MS), rheumatoid arthritis and post-traumatic stress disorder (PTSD).

The study, reported earlier this month in the Journal of Translational Medicine, raises hopes a single therapy might be formulated to treat chronic fatigue in all five conditions – a total of around 5.7 million Britons.

Scientists studied the genetic make-up of people with all five illnesses and found they shared a common trait – a genetic ‘switch’ seemingly causing severe fatigue.

Research lead Professor Dmitry Pshezhetskiy, who specialises in treating ME/CFS, told Good Health: ‘The thing that links all these conditions is that patients frequently report remarkably similar symptoms – overwhelming fatigue, brain fog, poor concentration, disturbed sleep and a dramatic reduction in everyday functioning.’

He and his team found similar ‘epigenetic’ changes in patients with these conditions.

Epigenetics is where environmental factors such as stress and diet can switch genes on or off, so parts of our bodies’ systems behave differently.

Although different genes were implicated in each condition, the result was the same in that the epigenetic switch that was tripped affected energy production – which could lead to chronic exhaustion.

Those epigenetic changes may also disrupt the ways in which our bodies regulate metabolism, react to infection and respond to stress, he adds.

‘One of the most significant aspects of this discovery is that it provides objective, blood-based biological proof of disease,’ he told Good Health.

Other studies in recent years have also highlighted physical causes that could explain symptoms of ME/CFS.

For example, an Australian study last year found ME/CFS was linked to simultaneous disruptions in the way sufferers’ bodies generate energy and regulate their immune systems, reported the journal Cell.

Other studies have suggested chronic fatigue can be caused by the immune system being over-reactive, treating normal stress as an infection, and causing exhausting, flu-like symptoms.

For patients with CFS such as Emma Slack, a mother-of-one from Newcastle, evidence of a distinct genetic cause also promises to help dispel the scepticism and dismissiveness that persistently confronts them.

For years, Emma, 35, endured prejudice and disbelief – before finally having her debilitating tiredness, brain fog and sleep problems diagnosed as CFS.

Doctors initially blamed anxiety and sent her for counselling. She says others have implied she is lazy and ought to start running (previously doctors told ME/CFS patients to exercise, regardless of how they felt after doing it – but in 2021, the National Institute for Health and Care Excellence did a U-turn on this advice).

Emma’s symptoms emerged in 2008, when she was 17.

‘I became unwell with a viral illness that was suspected to be glandular fever,’ she says. ‘I felt fluey with muscle aches and was so nauseous that I could not eat and I had fainting attacks.’

Before contracting her viral illness, Emma had been very active, a keen dancer and runner.

But she never recovered her energy levels and has since suffered with ongoing symptoms of fatigue, brain fog and sleep problems, which worsen if she does too much.

Over the years, her symptoms fluctuated. Although Emma was able to study, eventually getting a PhD in epidemiology, her illness meant she frequently had to go part-time and work from home.

‘For years, I did not know what was wrong with me,’ she recalls. ‘While on work placements for my degree I started to suffer badly. I went to the doctors and I was misdiagnosed as having anxiety.’

Emma consulted a counsellor: ‘They told me that the symptoms were just down to “my inner child being stubborn, and that I needed to tell them that I was OK”.’

She was told to push herself harder – but ‘it just made my symptoms so much worse’.

Then she was finally referred to a specialist and in 2017 was diagnosed with ME/CFS.

‘It was a huge relief to have a diagnosis that finally made sense,’ she says. ‘However, this brought the realisation that there was nothing anyone in medicine could really do for me. There was no treatment offered, only advice on managing my condition by pacing myself.’

Meanwhile, the medical scepticism she experienced continued.

Emma recalls how, in 2022 when she was pregnant, ‘my first obstetrician simply did not want to engage with my ME/CFS and refused to consider how it might affect the pregnancy. I had to find another who, thankfully, really listened and took it on board.

‘During my pregnancy, my symptoms got worse – and they continued to worsen afterwards when I was breastfeeding.

‘That’s not necessarily typical – the limited available research suggests some women’s symptoms get worse in pregnancy, some get better and some see no change,’ says Emma, now a research engagement officer with the charity ME Research UK.

She adds: ‘Thankfully, my health has stabilised over the past four years.

‘But there are still times when I need help just to get up the stairs. Often a flare-up means I’m in bed for a day or two.

‘My brain function goes and I can’t even answer simple questions.’ The delay in diagnosis is far from uncommon, says Professor Pshezhetskiy.

His hope now is that the findings will pave the way to a blood test that can rapidly diagnose patients with chronic fatigue conditions and lead to individually targeted ‘epigenetic drugs’ to ‘help the cell to reprogramme its signalling to a healthy state’.

‘This would avoid patients suffering from years of medical gaslighting and misdiagnosis,’ he told Good Health. However, other scientists are urging caution about the latest findings.

Charles Shepherd is a medical doctor and honorary medical adviser to the UK charity, the ME Association. The association’s official response is that: ‘More research is required. The conclusions that Professor Pshezhetskiy and his colleagues are making here are still quite speculative and unproven.’

Dr Shepherd told Good Health: ‘Another problem is that, having identified these as areas with underlying pathology, how do we fix them? How do we repair dysfunctional immune systems and improve cells’ energy production? Science doesn’t know at the moment.

‘Until we fully understand the mechanisms underlying CFS, we will just be tackling symptoms.

‘But it is helpful that there is growing recognition that chronic fatigue syndromes are real.’

Carmine Pariante, a professor of biological psychiatry at King’s College London, warned the research ‘does not identify novel mechanisms or concepts’.

However, he adds: ‘The confirmatory evidence in this paper will be helpful for researchers in the field as well as people who live with these disorders.’