The most common diagnosis was anxiety, found in 17% of those treated for Covid-19, followed by mood disorders, found in 14% of patients.
And while the neurological effects are more severe in hospitalized patients, they remain common in those who were only treated on an outpatient basis, the researchers note.
“That rate progressively increased as the severity of Covid-19 disease increased. If you look at the patients who were hospitalized, that rate increased to 39%,” said Maxime Taquet, an academic clinical researcher in psychiatry at the University of Oxford and co-author of the new study.
The results help light the way for how the healthcare system should continue to help Covid-19 survivors, the researchers said.
“Our results indicate that brain diseases and psychiatric disorders are more common after Covid-19 than after flu or other respiratory infections, even when patients are matched for other risk factors. Now we need to see what happens after the six months, “Taquet added.
Covid-19 as a ‘brain disease’
It is the largest study of its kind to date and involved the electronic health records of more than 236,000 Covid-19 patients, primarily in the US The researchers compared their records with those who experienced other respiratory tract infections during the same period of time.
They observed that people with Covid-19 had a 44% higher risk of neurological and psychiatric illnesses compared to people recovering from the flu. And they were 16% more likely to experience those effects compared to people with other respiratory tract infections.
About one in 50 Covid-19 patients had an ischemic stroke, which is a blood clot that affects the brain.
However, Covid-19 did not necessarily increase the risk of the entire spectrum of neurological diseases.
“Two important negative findings were related to parkinsonism and Guillain-Barré syndrome,” Taquet said. “Both of these conditions are neurological conditions that we know are sometimes associated with viral infections. We did not find that they were more common after Covid-19 and after the other respiratory tract infections that we analyzed.”
The study was important, in part, because of the large number of patient records the researchers were able to analyze, according to Dr Musa Sami, associate clinical professor of psychiatry at the University of Nottingham.
“This is solid work in a large cohort demonstrating the association between Covid-19 and psychiatric and neurological complications,” he said in a statement. “This is a very important issue, as there has been considerable consternation regarding Covid-19 as a ‘brain disease.’
Sami, who was not associated with the study, highlighted the need for further research on how, exactly, Covid-19 affects the brain and nervous system. “Psychological stress, longer hospital stays and the characteristics of the illness itself can play a role,” he said.
One hint: psychological symptoms are more common than severe neurological complications, according to Masud Husain, professor of neurology and cognitive sciences at the University of Oxford and a co-author of the study.
“It really is people with very serious illnesses who are at the highest risk of developing neurological complications, unlike what we see with mental health complications, which are much more serious across the board,” he said.
The long-term burden of Covid-19 on the healthcare system
One limitation of the Lancet Psychiatry study is that it uses “routine health care data” rather than research data, according to Paul Harrison, a professor of psychiatry at the University of Oxford and lead author of the study.
That could mean diagnoses are missing, have not been fully investigated, or are incorrect.
And just being diagnosed could make a difference.
“Patients who had Covid-1919 could be more likely to have a neurological and psychiatric diagnosis, simply because they received more follow-up, more medical care, compared to patients with respiratory tract infections. That could explain some of the differences that” I’ve looked at the rates, “Taquet said at a news conference.
But still, the study offers a broad view of the long-term burden the pandemic will have on those who hit it.
“Although the individual risks of most disorders are small, the effect on the entire population can be substantial for health and social care systems due to the scale of the pandemic and the fact that many of these conditions are chronic. Harrison said. “As a result, health care systems must have the resources to meet anticipated needs, both within primary and secondary care services.”