21st July 2023 – by King’s College London

Researchers from TwinsUK have found that people with longer-term COVID-19 symptoms including brain fog showed reduced performance in tasks testing different mental processes up to two years after infection with the virus.  

The team looked at whether infection with COVID-19 affected performance in two rounds of online cognitive testing that took place in 2021 and 2022. Data was collected for over 3,000 participants of the COVID Symptom Study Biobank study, across 12 tasks that tested memory, attention, reasoning, processing speed and motor control.  

The participants whose test scores were most affected by COVID-19 were those who had experienced symptoms related to the virus for 12 weeks or more. In these people, the effect of COVID-19 on test accuracy was comparable in size to the effect of a 10-year increase in age.  

There was no significant improvement in these test scores between the two rounds of testing, which took place nine months apart. By the second round of testing, the average time since participants’ initial COVID-19 infection was almost two years.  

Digging deeper into the analysis, the researchers separated participants by whether they felt fully recovered following COVID-19 infection. People who felt fully recovered after COVID-19 infection performed similarly to those who had not had the virus at all. In contrast, participants who did not feel fully recovered after infection had lower task accuracy scores on average.  

Lead author Dr Nathan Cheetham said: 

“Our findings suggest that, for people who were living with long-term symptoms after having COVID-19, the effects of the coronavirus on mental processes such as the ability to recall words and shapes are still detectable at an average of almost two years since their initial infection.  

“However, the result that COVID had no effect on performance in our tests for people who felt fully recovered, even if they’d had symptoms for several months and could be considered as experiencing ‘long COVID’, was good news. This study shows the need to monitor those people whose brain function is most affected by COVID-19, to see how their cognitive symptoms continue to develop and provide support towards recovery.”  

Professor Claire Steves added: 

“We used sensitive tests to measure speed and accuracy across a range of brain challenges. This study shows that some individuals have measurable changes in these tests after COVID-19 going on for nearly two years. The fact remains that two years on from their first infection, some people don’t feel fully recovered and their lives continue to be impacted by the long-term effects of the coronavirus. We need more work to understand why this is the case and what can be done to help.” 

17^th April 2023 – by King’s College London 

The paper recently published in Lancet Digital Health identifies patterns among people infected with the wild-type, the first strain of SARS-CoV-2, and Delta and Alpha variants, among vaccinated and unvaccinated individuals. 

Researchers from TwinsUK analysed data of 1,459 individuals who have experienced ongoing symptoms for longer than 84 days, known clinically as post-covid syndrome or long COVID, from the ZOE Health Study. 

The analysis adds to emerging evidence that long COVID is not a homogenous illness and should have personalised treatment and care. The team recommend the findings to be used by researchers investigating why and how long-COVID occurs, healthcare services providers, as well for people living with long COVID. 

People with symptoms for 12 weeks or more fell into three main groups based on the types of symptoms they were experiencing. The largest group was characterised by a cluster of neurological symptoms such as fatigue, brain-fog and headache and was the most common subtype among alpha and delta variants. A second group experienced respiratory symptoms including chest pain and severe shortness of breath, which could point to lung damage. This was the largest cluster in the wild-type period when the population was unvaccinated. Finally, there were some people who experienced a diverse range of symptoms including heart palpitations, muscle ache and pain, and changes in skin and hair. 

Crucially, the data also suggested that the symptom types for people who did experience symptoms for 12 weeks or more were similar in vaccinated and unvaccinated people at least with variants which had these data. Existing data shows that the risk of long-COVID overall is reduced by vaccination. 

Professor Claire Steves explained:  

“These data show clearly that post COVID syndrome is not just one condition but appears to have at several subtypes. Our findings matched with people’s experience living with long COVID. Understanding the root causes of these subtypes may help in finding treatment strategies. Moreover, these data emphasise the need for Long-COVID services to incorporate a personalised approach sensitive to the issues of each individual.” 

While these three subtypes were evident in all variants, additional symptom clusters were also identified which were subtly different between variants. These differences may not be due to variants themselves, but other factors which have changed across the pandemic, such as time of year, social behaviours, and treatments. 

Given that the data used was collected over an interval of time, the study is relevant for post-COVID predictions, indicating how long certain symptoms could last. These insights could aid in the development of personalised diagnosis and treatment for these individuals. 

26th January 2022 – By Aaruthy Suthahar

Scientists have found the “booster” COVID-19 vaccine programme led to a large boost in the antibodies that help protect against coronavirus. High levels of antibodies is associated with lower risk of severe infection.

The study, which is part of the National Core Study for Longitudinal Health and Wellbeing, is published today in the scientific journal eLife. Researchers from King’s College London, Bristol University, UCL and several other institutions around the UK teamed up to work on the project.

Researchers analysed blood samples from 9,361 participants from two UK population cohorts, with 4,739 participants from TwinsUK and 4,622 from Children of the 90s (also known as the Avon Longitudinal Study of Parents and Children). Samples were tested to measure antibodies generated by vaccination, and examine whether certain groups were more likely to have lower levels of antibodies. Lower levels are known to be linked to higher risk of coronavirus infection.

Similar to previous research, the study found higher infection rates among participants with lower levels of antibodies after a first vaccination. However, researchers also found large increases in antibodies with each round of vaccination. The level of antibodies was around 10 times higher in the first weeks after a third vaccine compared to those who had only received two vaccinations an average of six months earlier.

Some groups of individuals had consistently lower levels of antibodies after vaccination. In particular, people advised to “shield” in the first year of the COVID-19 pandemic because of an increased risk of complication due to COVID-19 were more likely to have fewer antibodies. The good news was that even these individuals mounted a strong response to the booster.

Researchers also found a third dose appeared to eliminate a key difference in antibody levels based on the type of vaccine received. While people who received the Oxford/AstraZeneca vaccine were more likely to have lower antibody levels than those who received Pfizer-BioNTech after one or two vaccinations, this difference was no longer present after a third vaccination.

Findings also showed people who had a confirmed coronavirus infection before vaccination were more likely to have higher levels of antibodies, compared to those without confirmed infection.

First author Dr Nathan Cheetham explained:

“ Our findings support a policy of a third (and now fourth) COVID-19 vaccination to boost antibodies and protect against COVID-19. This is especially true for people who had the Oxford/AstraZeneca vaccine for their first and second jabs. ”

“ Our results also showed that some people are more likely to have a weaker response to vaccination than others, which we hope will be useful for policy-makers when considering any future COVID-19 vaccinations. In particular, we saw in participants from both TwinsUK and Children of the 90s cohorts that the “Shielded Patient List” criteria were an effective means to identify those with lower response to vaccination, despite the guidance to shield no longer being in place. ”

Professor Claire Steves said:

“We were particularly pleased to see that individuals at higher risk of severe infection still responded well to the booster vaccination. This is further evidence that coming forward for a booster vaccination is a good idea as COVID is still very much around.”

22nd November 2022 – By Aaruthy Suthahar

Your X chromosome contains clues as to whether or not you might develop cancer and heart disease, according to latest research from TwinsUK. 

Chromosomes are lengths of DNA that contain genes on them. Human males have both an X and a Y chromosome, and females have two X chromosomes (XX). We only need one dose of the genes on the X chromosome, so in females, one of the X chromosomes in every cell is switched off so they do not get double the dose. 

This process of X-inactivation is meant to happen at random, but researchers have identified that in some people as they age, one X is more likely to be inactivated than the other. In this study, the team identified that skew in X-inactivation (XCI) is associated with chronic health outcomes. They found that XCI-skew in older females can pick up on changes that occur in a population of blood cells and can be used as a potential biomarker to recognise the risk of developing chronic conditions.  

Ageing is a complex process that involves different cellular and molecular features, which includes alteration to blood cells and makes an individual more susceptible to developing chronic conditions.  

The team studied 1,575 female TwinsUK members to examine XCI skew and its link with ageing, risk of developing heart disease, and cancer diagnoses.  

Researchers also found that XCI-skew is linked with the number of years an individual has lived and increases over someone’s life span. The changes in the frequency of XCI-skew were examined across increasing ages and identified 12% of participants below 40 years old displaying XCI-skew, 28% of 40–59-year old’s; 37% of 60–69-year old’s; and 44% of those over 70-year-old. 

Furthermore, results showed that a skewed XCI can predict future cancer detection in a 10-year follow-up. They found that using a heart disease risk score, picked up on specific risk factors, and can predict the risk of a major heart disease event in the next 10 years, with a heart disease risk score greater than 7.5% characterizing an intermediate-risk, and a heart disease risk score greater than 20% characterizing substantial risk. 

A limitation of the study was that the sample sizes restricted the chances of carrying out investigations on specific deaths or cancer types. 

First author Dr Amy Roberts explained: 

“This study provides a better understanding of the link between X chromosome inactivation and our health and might help explain why some twins develop chronic diseases even if their co-twin does not. Further research is needed to convert the biological usefulness of skewed XCI into clinical applications for investigating the link between blood cell changes as someone ages and association with chronic disease, despite chromosomal sex.” 

This paper is part of a broader programme of work investigating how the X chromosome affects our health. 

14th October 2022 – By King’s College London

Having symptoms of COVID-19 has been associated with worse mental health and lower life satisfaction.

The study, which is part of the COVID-19 Longitudinal Health and Wellbeing National Core Study, is published today in The Lancet Psychiatry. It is led by researchers from King’s and University College London in collaboration with several UK institutions. 

Data was taken from 11 longitudinal studies between April 2020 and April 2021, in which there were 54,442 participants with and without self-reported COVID-19. The study looked at the impact of COVID-19 infection on subsequent mental health and well-being.

Researchers found that rises in psychological distress, depression, anxiety, and lower life satisfaction were associated with prior self-reported COVID-19. The associations with poorer mental health did not lessen over time after infection, highlighting the potential enduring impacts of the disease and the need for a longer follow-up process from healthcare providers.

Self-reported COVID-19 was consistently associated with psychological distress, regardless of whether people tested positive for antibodies to the virus. These effects of infection were felt similarly in different groups of gender, ethnicity, and socio-economic circumstances.

The study suggests that the infection of COVID-19 might impact mental health most in older people as people with self-reported infection aged 50 years and older showed a stronger association with poorer mental health. This might reflect that older people are more likely to experience more severe COVID-19 symptoms, greater worry around infection, and increased risk of blood vessel (microvascular) or brain (neurological) changes after infection. This contrasts with the effect of the pandemic overall on mental health, where previous studies have shown that women and adults aged 25-44 have had the greatest adverse impacts.

Joint first author Dr Ellen Thompson from The School of Life Course & Population Sciences said:

“These findings suggest that there were prolonged mental health consequences of COVID-19 infection for some people at the beginning of this pandemic. Understanding why this is the case will be key to finding treatment strategies for those affected as well as preventing such effects in future pandemic waves.”

Senior author Prof Praveetha Patalay from University College London said:

“This study brings together many of the UK’s longitudinal studies to provide a comprehensive overview of the impacts of COVID-19 infection on population mental health. Compared to most studies to-date that have focussed on more severe and hospitalised cases, this study demonstrates the impact of infection during a pandemic on overall population mental health and wellbeing.”