From the start of the COVID-19 pandemic, there have been concerns that survivors may have an increased risk of neurological and mental health conditions.
There was also early evidence that the illness can affect the central nervous system.
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In November 2020, an observational study from scientists at the University of Oxford, in the United Kingdom, reported that survivors had a greater risk of developing mood and anxiety disorders in the 3 months after receiving a COVID-19 diagnosis.
The same researchers have now used the health records of more than 236,000 patients in the U.S. to estimate the risks of developing neurological and psychiatric conditions in the 6 months after a COVID-19 diagnosis.
Participants had received COVID-19 diagnoses between January 20 and December 13, 2020.
The researchers estimate that the overall incidence of neurological or mental health diagnoses was 34%.
In the 6 months after their COVID-19 diagnoses, 13% of the participants received their first diagnosis of a neurological or psychiatric condition.
The most common diagnoses were anxiety disorders, in 17% of all the participants, mood disorders, in 14%, substance misuse disorders, in 7%, and insomnia, in 5%.
The incidence of neurological disorders was lower — 2.1% of all the participants experienced an ischemic stroke, 0.7% developed dementia, and 0.6% developed a brain hemorrhage.
This new study has been published in The Lancet Psychiatry.
Links with disease severity
Those who experienced more severe COVID-19 had a greater risk of mental health and neurological diagnoses.
Participants who experienced delirium, which is a sudden state of confusion, or encephalopathy, which is brain disease or damage, during their illnesses had the highest overall risk, at 62%, during the following 6 months.
Prof. Paul Harrison, the senior author of the study, says that the results confirm the high rates of mental health diagnoses after COVID-19.
He emphasized that while the incidence of neurological disorders was much lower than that of mental health conditions, this risk was still significant, particularly among people with severe COVID-19.
Prof. Harrison believes that resources to cope with the extra demands on primary and secondary care services should be provided.
“Although the individual risks for most disorders are small, the effect across the whole population may be substantial for health and social care systems due to the scale of the pandemic, and […] many of these conditions are chronic,” he adds.
They compared outcomes for this group with those of 105,579 people with influenza and 236,038 people with any respiratory tract infection diagnosed between January and December 2020. The latter two groups acted as controls.
To account for underlying health risks, the team matched the people in each group in terms of characteristics such as age, sex, ethnicity, and other ongoing health conditions.
“We now need to see what happens beyond 6 months,” says Dr. Maxime Taquet, the lead author of the research paper.
“The study cannot reveal the mechanisms involved but does point to the need for urgent research to identify these, with a view to preventing or treating them,” he add.