34% of Covid-19 convalescents have been diagnosed with a neurological or psychiatric disorder within six months of infection, concludes a British study of more than 230,000 people. These disorders range from anxiety to dementia, observe researchers in The Lancet Psychiatry, with a risk all the more important as the disease was serious.
Known neurological disorders
“Since the start of the Covid-19 pandemic on March 11, 2020, we have been concerned about the increased risk of neurological disorders in survivorsThe authors state in the publication. Disorientation, headaches, confusion, memory problems and numbness are among the neurological symptoms seen in patients with Covid-19. Researchers quickly realized that the virus was infecting the brain , and more precisely neurons, sometimes to the point of causing cognitive decline, even dementia or a drop in IQ.
With more than a year of hindsight on the first Western patients, researchers at the University of Oxford (England) used data from the American network TriNetX, which includes the files of more than 81 million people. Among them, the researchers looked at 236,359 patients who had Covid-19 and recovered from it, and compared them to more than 100,000 people who had recovered from the flu, and more than 230,000 who suffered from any respiratory infection. (including influenza) with the exception of Covid-19.
A third of Covid-19 patients develop neurological or psychiatric disorders
As a result, 34% of patients leaving Covid-19 were diagnosed with a neurological or psychiatric disorder within six months of infection. For 13%, it was their first such diagnosis. The most common diagnoses following a Covid-19 were anxiety disorders (17% of patients), mood disorders (14%), substance abuse disorders (7%) and insomnia (5%). The incidence of neurological findings was lower, including 0.6% for cerebral hemorrhages, 2.1% for ischemic strokes (a type of stroke) and 0.7% for dementia.
This real world data “confirm high rates of psychiatric diagnoses after Covid-19, and show that serious disorders affecting the nervous system (such as stroke and dementia) also occur“, concludes lead author Paul Harrison in a statement. The severity and durability of the disorders diagnosed, however, were not known.
More serious disorders in severe Covid
These serious disorders affecting the nervous system are “much rarer, but significant, especially in those who have suffered severe Covid-19“, adds Paul Harrison. Thus, 2.7% of people requiring intensive care had a cerebral hemorrhage (against 0.3% in non-hospitalized people), 6.9% had an ischemic stroke (against 1 , 3% without hospitalization), and 1.7% developed dementia (0.4% without hospitalization).
In general, more severe Covid-19s increased the risk of a neurological or psychiatric disorder. Thus, these disorders were declared in 38% of people who had been admitted to hospital (compared to 34% overall), in 46% of those in intensive care and in 62% of those who had had a delirium ( encephalopathy) during their infection with Covid-19.
More common than after the flu
This risk of neurological and mental diagnoses was overall 44% higher after Covid-19 than after the flu, and 16% higher than with respiratory tract infections combined, the researchers then point out. “Our results indicate that brain diseases and psychiatric disorders are more common after Covid-19 than after influenza or other respiratory infections“, even with equivalent risk factors, points out in a press release Max Taquet, co-author of the study.
Should we blame the virus or the crisis?
It is difficult to know what is the direct action of the virus on neurons, and what is the stress linked to the disease, the management of the pandemic or the global crisis that the world is going through. The British study is observational, so it can only see correlations between the disease and the sequelae, but it cannot explain the mechanism. Researchers have several hypotheses. Common psychiatric disorders, such as anxiety or insomnia, were almost as present in mild Covid as severe. For researchers, this could indicate “that their onset reflects, at least partially, the psychological and other implications of a Covid-19 diagnosis rather than being a direct manifestation of the disease“.
As for the other more serious symptoms, which increase in probability as the disease is severe, they suspect a viral invasion of the nervous system (including the brain), hypercoagulation which would lead to strokes, or neural effects of the immune response which s ‘packed up.