Many people with severe COVID-19 have mental and cognitive problems for more than 6 months afterwards, but the percentage with mental health problems is not higher than for comparable people hospitalised without COVID-19. Nevertheless, severe COVID-19 does appear to affect cognition more than hospitalisation for other reasons – but not by much.
People who have experienced severe COVID-19 can have poorer mental health for several months afterwards.
A new study confirms this, but the proportion of people who have mental health problems after severe COVID-19 is not greater than that following any other disease trajectory of similar severity.
The results come from a study in which researchers followed people who were hospitalised, including the ones that received intensive care, at Rigshospitalet in Copenhagen for COVID-19 and for other diseases.
However, the study also shows that severe COVID-19 does appear to affect cognition more strongly.
“There has been much discussion that COVID-19 can have mental, nervous system and cognitive side-effects, but this neglects the fact that other disease trajectories can have the same effects. People receiving intensive care may experience anxiety and depression long afterwards. This study investigated for the first time whether people with severe COVID-19 have a greater risk of long-term mental and cognitive problems than a comparable control group,” explains a researcher behind the study, Michael Eriksen Benros, Professor and Head of Research, Mental Health Centre Copenhagen and at the Department of Immunology and Microbiology, University of Copenhagen.
The research has been published in JAMA Psychiatry.
Comparing people with severe COVID-19 versus other diseases for the first time
For 6 months, the researchers followed people hospitalised at Rigshospitalet: 85 with COVID-19 and 61 controls with other diseases, such as cardiovascular disease.
The researchers matched these patients for age, time in hospital, inflammation markers and other indicators.
The researchers invited them to participate in studies to identify mental problems and assess cognitive functioning at the time of discharge and for 6 months afterwards.
“These people were critically ill, so we did not study people’s problems after mild COVID-19,” says Michael Eriksen Benros.
One in five had mental health problems 6 months afterwards
The results show that 19% of the people with severe COVID-19 and 20% of the matched controls met the criteria for a new mental disorder diagnosis such as anxiety, depression or post-traumatic stress syndrome 6 months after hospitalisation.
The researchers found that 81% of the people with severe COVID-19 and 93% of the matched controls experienced mental health symptoms.
Another researcher behind the study, Vardan Nersesjan, PhD student, Mental Health Centre Copenhagen and Department of Immunology and Microbiology, University of Copenhagen says that, early in the pandemic, studies indicating that a high proportion of inpatients with COVID-19 had symptoms indicating a mental disorder 6 months later, which was worrying, and could have indicated that this was unique to COVID-19.
“That is why comparing with a control group to determine the situation for people without COVID-19 is so important. The numbers are quite similar, but it is worrying that every fifth patient meets the criteria for a mental disorder 6 months after hospitalisation. The question is whether this focus on late COVID-19 should also result in a general focus on mental health after hospitalisation for severe illness,” explains Vardan Nersesjan.
COVID-19 affects cognition more strongly
Severe COVID-19 appeared to more strongly affect cognition in the long term than other diseases.
Based on the Montreal Cognitive Assessment, severe illness especially strongly affected tasks that require concentration and attention ability in both groups but to a greater extent among people with severe COVID-19.
The mean cognitive scores between those with COVID-19 and the matched controls differed by only 0.8 points. To put this in perspective, the mean cognitive test score among those with COVID-19 improved from 19.2 at discharge to 26.1 at 6 months later, a difference of 6.9 points. Thus, their cognition improved strongly after discharge.
“The groups differed significantly after 6 months, but this is relatively modest given the level of improvement. However, this can result in a greater social burden now that COVID-19 has been so widespread,” says a third researcher behind the study, Daniel Kondziella, Clinical Research Associate Professor and Consultant Neurologist, Department of Neurology, Neuroscience Centre, Rigshospitalet and Department of Clinical Medicine, University of Copenhagen.
Further research required
The researchers are underway with a new follow-up study with more participants and longer duration of follow-up.
According to Michael Eriksen Benros, if the researchers confirm the results, this could indicate the need for further studying the underlying mechanisms that link COVID-19 and other severe illness to subsequent mental health and cognitive problems.
“People with severe illness are affected no matter what. We have seen this before, and now we have seen it again. We are therefore considering whether some kind of follow-up should be ensured for people after severe illness, because we now know that they experience long-term symptoms,” he says.
The researchers also want to study the potential causal mechanisms.
“This may result from the immune system affecting the brain in response to disease, or from complications in the brain that sometimes inevitably result from prolonged treatment in the intensive care environment.“
Although a virus may enter the brain occasionally, this does not appear to be a big contributing factor.
“There are various possibilities for which more knowledge is needed so that we can reduce the long-term effects a severe disease trajectory can have on the brain. One way to do this is to collect blood and cerebrospinal fluid for analysis for potential biomarkers among people with long COVID,” concludes Daniel Kondziella.