In the study, sensitivity was defined as a personality trait that reflects people's capacity to perceive and process environmental stimuli such as bright lights, subtle changes in the environment and other peoples' moods. Often overlooked in mental health studies and clinical practice, which tend to focus on neuroticism and its association with mental health conditions, this research shows that understanding a person's sensitivity level is important and can have therapeutic implications.

For example, people with more sensitive personality traits may be more likely to benefit from treatment plans which involve techniques such as applied relaxation and mindfulness, which can also prevent relapse.

Tom Falkenstein, a psychotherapist and a PhD student at Queen Mary University of London, said: "This is the most extensive systematic review on sensitivity and mental health in adolescents and adults to date, and is the first ever meta-analysis on the topic to estimate the impact of this relationship. We found positive and moderate correlations between sensitivity and various mental health problems such as depression, anxiety, post-traumatic stress disorder, agoraphobia and avoidant personality disorder. Our findings suggest that sensitivity should be considered more in clinical practice which could be used to improve diagnosis of conditions."

"In addition, our findings could help improve treatment for these individuals. Around 31% of the general population are considered highly sensitive, and, as our findings show, are more likely to respond better to some psychological interventions than less sensitive individuals. Therefore, sensitivity should be considered when thinking about treatment plans for mental health conditions. Our work shows it is crucial that the awareness of sensitivity is improved among mental health care professionals, so clinicians and practitioners can recognize the trait in their patients, and tailor treatment to their sensitivity."

Michael Pluess, Professor in Developmental Psychology at University of Surrey and Visiting Professor at Queen Mary University of London said:

"This is the first meta-analysis providing robust evidence that highly sensitive people are more prone to common mental health problems. However, it is important to remember that highly sensitive people are also more responsive to positive experiences, including psychological treatment. Our results provide further evidence that sensitive people are more affected by both negative and positive experiences and that the quality of their environment is particularly important for their well-being."

The systematic review and meta analysis of 33 studies was carried out by an academic team from several universities including Queen Mary University and the University of Surrey.

Authors include Tom Falkenstein (Queen Mary University of London), Luke Satori (Kings College London), Margherita Malanchini, (Queen Mary University of London) Kristin Hadfield (Trinity College Dublin) and Michael Pluess (University of Surrey).

Blood vessels gradually become stiffer with age, but the new study suggests that Covid could accelerate this process. Researchers say this is important since people with stiffer blood vessels face a higher risk of cardiovascular disease, including stroke and heart attack.

The study was led by Professor Rosa Maria Bruno from Université Paris Cité, France. She said: "Since the pandemic, we have learned that many people who have had Covid are left with symptoms that can last for months or even years. However, we are still learning what's happening in the body to create these symptoms.

"We know that Covid can directly affect blood vessels. We believe that this may result in what we call early vascular aging, meaning that your blood vessels are older than your chronological age and you are more susceptible to heart disease. If that is happening, we need to identify who is at risk at an early stage to prevent heart attacks and strokes."

The study included 2,390 people from 16 different countries (Austria, Australia, Brazil, Canada, Cyprus, France, Greece, Italy, Mexico, Norway, Turkey, UK and US) who were recruited between September 2020 to February 2022. They were categorized according to whether they had never had Covid, had recent Covid but were not hospitalized, hospitalized for Covid on a general ward or hospitalized for Covid in an intensive care unit.

Researchers assessed each person's vascular age with a device that measures how quickly a wave of blood pressure travels between the carotid artery (in the neck) and femoral arteries (in the legs), a measure called carotid-femoral pulse wave velocity (PWV). The higher this measurement, the stiffer the blood vessels and the higher the vascular age of a person. Measurements were taken six months after Covid infection and again after 12 months.

Researchers also recorded demographic information such as patient's sex, age and other factors that can influence cardiovascular health.

After taking these factors into consideration, researchers found that all three groups of patients who had been infected with Covid, including those with mild Covid, had stiffer arteries, compared to those who had not been infected. The effect was greater in women than in men and in people who experienced the persistent symptoms of long Covid, such as shortness of breath and fatigue.

The average increase in PWV in women who had mild Covid was 0.55 meters per second, 0.60 in women hospitalized with Covid, and 1.09 for women treated in intensive care. Researchers say

an increase of around 0.5 meters per second is "clinically relevant" and equivalent to aging around five years, with a 3% increased risk of cardiovascular disease, in a 60-year-old woman.

People who had been vaccinated against Covid generally had arteries that were less stiff than people who were unvaccinated. Over the longer term, the vascular aging associated with Covid infection seemed to stabilize or improve slightly.

Professor Bruno said: "There are several possible explanations for the vascular effects of Covid. The Covid-19 virus acts on specific receptors in the body, called the angiotensin-converting enzyme 2 receptors, that are present on the lining of the blood vessels. The virus uses these receptors to enter and infect cells. This may result in vascular dysfunction and accelerated vascular aging. Our body's inflammation and immune responses, which defend against infections, may be also involved.

"One of the reasons for the difference between women and men could be differences in the function of the immune system. Women mount a more rapid and robust immune response, which can protect them from infection. However, this same response can also increase damage to blood vessels after the initial infection.

"Vascular aging is easy to measure and can be addressed with widely available treatments, such as lifestyle changes, blood pressure-lowering and cholesterol-lowering drugs. For people with accelerated vascular aging, it is important to do whatever possible to reduce the risk of heart attacks and strokes."

Professor Bruno and her colleagues will continue to follow the participants over the coming years to establish whether the accelerated vascular aging they have found leads to an increased risk of heart attacks and strokes in the future.

In an accompanying editorial Dr Behnood Bikdeli from Harvard Medical School, Boston, USA and colleagues said: "Although the acute threat of the COVID-19 pandemic has waned, a new challenge emerged in its aftermath: post-acute COVID-19 syndrome. Defined by the World Health Organization as symptoms appearing three months post-infection and lasting at least two months, studies suggest that up to 40% of initial COVID-19 survivors develop this syndrome.

"This large, multicentre, prospective cohort study enrolled 2390 participants from 34 centres to investigate whether arterial stiffness, as measured by PWV, persisted in individuals with recent COVID-19 infection. […] sex-stratified analyses revealed striking differences: females across all COVID-19-positive groups had significantly elevated PWV, with the highest increase (+1.09 m/s) observed in those requiring ICU admission.

"The CARTESIAN study makes the case that COVID-19 has aged our arteries, especially for female adults. The question is whether we can find modifiable targets to prevent this in future surges of infection, and mitigate adverse outcomes in those afflicted with COVID-19-induced vascular aging."