Scientists in the United Kingdom say they have developed a blood test that can diagnose myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) with 96% accuracy – the first of its kind.

For many who live with the debilitating condition, this will be exciting news.

Despite affecting millions of people worldwide, this condition remains poorly understood. It is characterised by unrelenting fatigue that doesn’t improve with rest, and post-exertional malaise – a worsening of symptoms after even minor physical or mental activity.

Yet with no reliable test, many people wait years for a diagnosis. This usually depends on symptoms meeting certain clinical criteria. But diagnostic criteria can be controversial as they vary worldwide and many are outdated.

An accurate blood test could be a game changer for diagnosis.

So, how excited should we get? Here’s what we know.

How diagnosis works without a test

Currently, you can only receive a diagnosis if you experience disabling fatigue – one of the key symptoms according to most clinical criteria – for at least six months, accompanied by post-exertional malaise.

But people with the condition often experience a wide range of other symptoms, including headaches, muscle or joint pain, sleep disturbances, dizziness, a racing heart, and problems with memory, thinking and decision making.

So, clinicians must also rule out other conditions with overlapping symptoms.

This means diagnosis relies heavily on clinicians’ knowledge of ME/CFS and their willingness to listen to the patient’s complex symptom history. This process can take years – and the delay in diagnosis has real consequences.

Evidence suggests early intervention is key to recovery. Rest during the early stages of the illness likely results in better long-term outcomes, as has been suggested for the clinically similar disease long COVID.

One study showed a delayed ME/CFS diagnosis was linked to poorer outcomes, meaning recovery was less likely and the chance of developing more severe symptoms increased.

Without a definitive diagnosis, patients regularly face disbelief about their illness and have limited access to information, health-care services and medical benefits.

Frequent delays in diagnosis may contribute to the condition’s low recovery rate, which is estimated at just 1–10%.

What the new study looked at

To develop a diagnostic test, the new study identified biomarkers that may be specific to people with this condition.

In this case, the biomarkers relate to epigenetics – changes in the structure of a person’s chromosomes, influencing which genes can be turned on or off.

These changes occur due to environmental influences such as stress, infection and exercise. So, when someone develops ME/CFS, the illness may change the structure of their chromosomes – but until now researchers hadn’t identified what this would look like.

The researchers examined blood samples from people they knew had ME/CFS and identified around 200 such biomarkers. These changes formed a distinct biological “signature” that was not present in the blood of healthy participants in the comparison group.

This signature was very accurate in correctly identifying which samples were from people with the condition and which were from the comparison group.

According to the researchers, the test’s sensitivity was 92% – this is the probability a positive result will show when someone has the condition. It had a specificity of 98%, meaning the probability it can rule out negative cases.

This combined to an overall diagnostic accuracy of 96%.

So, is this a breakthrough?

This research is promising, but it’s still very early days. It was a proof-of-concept study, meaning small-scale research to initially test whether an idea might work.

In this case, researchers explored the idea that structural changes in chromosomes could be used as biomarkers of ME/CFS. Their results suggest they can.

However, there were several limitations. The study involved a relatively small number of people: 47 participants with severe ME/CFS and 61 in the healthy “control” group.

The ME/CFS group had more females, and its participants were so severely affected they were housebound. So they presumably had lower activity levels than the control group.

We know a person’s sex and activity levels can influence these chromosomal changes, so this may have affected the results.

To develop a diagnostic test that can be used widely, several crucial steps remain.

How much a person’s sex and exercise levels influence these biomarkers needs to be determined. The biomarkers will also need to be validated in larger, more diverse groups, which include people with less and more severe symptoms than in this study and those from different backgrounds.

To confirm these biomarkers are truly specific to ME/CFS, they need to be compared with other conditions that share similar symptoms, such as multiple sclerosis and fibromyalgia.

Finally, it’s also important that a test, if developed, should be affordable and accessible.

ME/CFS remains a severely underdiagnosed condition, and the lack of a reliable test continues to delay care and worsen outcomes. Identifying biomarkers, as this study aimed to do, is a promising first step.

Sarah Annesley, Senior Postdoctoral Research Fellow in Cell and Molecular Biology, La Trobe University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

A recent study has suggested Shingrix, a relatively new vaccine given to protect older adults against shingles, may delay the onset of dementia.

This might seem like a bizarre link, but actually, research has previously shown an older version of the shingles vaccine, Zostavax, reduced the risk of dementia.

In this new study, published last week in the journal Nature Medicine, researchers from the United Kingdom found Shingrix delayed dementia onset by 17% compared with Zostavax.

So how did the researchers work this out, and how could a shingles vaccine affect dementia risk?

From Zostavax to Shingrix

Shingles is a viral infection caused by the varicella-zoster virus. It causes painful rashes, and affects older people in particular.

Previously, Zostavax was used to vaccinate against shingles. It was administered as a single shot and provided good protection for about five years.

Shingrix has been developed based on a newer vaccine technology, and is thought to offer stronger and longer-lasting protection. Given in two doses, it’s now the preferred option for shingles vaccination in Australia and elsewhere.

In November 2023, Shingrix replaced Zostavax on the National Immunisation Program, making it available for free to those at highest risk of complications from shingles. This includes all adults aged 65 and over, First Nations people aged 50 and older, and younger adults with certain medical conditions that affect their immune systems.

What the study found

Shingrix was approved by the US Food and Drugs Administration in October 2017. The researchers in the new study used the transition from Zostavax to Shingrix in the United States as an opportunity for research.

They selected 103,837 people who received Zostavax (between October 2014 and September 2017) and compared them with 103,837 people who received Shingrix (between November 2017 and October 2020).

By analysing data from electronic health records, they found people who received Shingrix had a 17% increase in “diagnosis-free time” during the follow-up period (up to six years after vaccination) compared with those who received Zostavax. This was equivalent to an average of 164 extra days without a dementia diagnosis.

The researchers also compared the shingles vaccines to other vaccines: influenza, and a combined vaccine for tetanus, diphtheria and pertussis. Shingrix and Zostavax performed around 14–27% better in lowering the risk of a dementia diagnosis, with Shingrix associated with a greater improvement.

The benefits of Shingrix in terms of dementia risk were significant for both sexes, but more pronounced for women. This is not entirely surprising, because we know women have a higher risk of developing dementia due to interplay of biological factors. These include being more sensitive to certain genetic mutations associated with dementia and hormonal differences.

Why the link?

The idea that vaccination against viral infection can lower the risk of dementia has been around for more than two decades. Associations have been observed between vaccines, such as those for diphtheria, tetanus, polio and influenza, and subsequent dementia risk.

Research has shown Zostavax vaccination can reduce the risk of developing dementia by 20% compared with people who are unvaccinated.

But it may not be that the vaccines themselves protect against dementia. Rather, it may be the resulting lack of viral infection creating this effect. Research indicates bacterial infections in the gut, as well as viral infections, are associated with a higher risk of dementia.

Notably, untreated infections with herpes simplex (herpes) virus – closely related to the varicella-zoster virus that causes shingles – can significantly increase the risk of developing dementia. Research has also shown shingles increases the risk of a later dementia diagnosis.

The mechanism is not entirely clear. But there are two potential pathways which may help us understand why infections could increase the risk of dementia.

First, certain molecules are produced when a baby is developing in the womb to help with the body’s development. These molecules have the potential to cause inflammation and accelerate ageing, so the production of these molecules is silenced around birth. However, viral infections such as shingles can reactivate the production of these molecules in adult life which could hypothetically lead to dementia.

Second, in Alzheimer’s disease, a specific protein called Amyloid-β go rogue and kill brain cells. Certain proteins produced by viruses such as COVID and bad gut bacteria have the potential to support Amyloid-β in its toxic form. In laboratory conditions, these proteins have been shown to accelerate the onset of dementia.

What does this all mean?

With an ageing population, the burden of dementia is only likely to become greater in the years to come. There’s a lot more we have to learn about the causes of the disease and what we can potentially do to prevent and treat it.

This new study has some limitations. For example, time without a diagnosis doesn’t necessarily mean time without disease. Some people may have underlying disease with delayed diagnosis.

This research indicates Shingrix could have a silent benefit, but it’s too early to suggest we can use antiviral vaccines to prevent dementia.

Overall, we need more research exploring in greater detail how infections are linked with dementia. This will help us understand the root causes of dementia and design potential therapies.

Ibrahim Javed, Enterprise and NHMRC Emerging Leadership Fellow, UniSA Clinical & Health Sciences, University of South Australia

This article is republished from The Conversation under a Creative Commons license. Read the original article.