Neurological and psychiatric symptoms such as anosmia and depression are common among people with covid-19 and may be just as likely in people with mild cases, new research suggests.
Evidence from 215 studies of people with covid-19 indicates a wide range of ways in which the condition can affect mental health and the brain.
The studies, from 30 countries, involved a total of 105,638 people with acute symptoms of covid-19 – the initial illness, rather than the longer-term impacts seen in long covid – including data up to July 2020.
“We had expected that neurological and psychiatric symptoms would be more common in severe covid-19 cases, but instead we found that some symptoms appeared to be more common in mild cases,” said Jonathan Rogers at University College London, the lead author of the study.
“It appears that covid-19 affecting mental health and the brain is the norm, rather than the exception.”
The most common neurological and psychiatric symptoms were anosmia – loss of smell – reported by 43 per cent of people with the illness, weakness (40 per cent), fatigue (38 per cent), loss of taste (37 per cent), muscle pain (25 per cent), depression (23 per cent), headache (21 per cent) and anxiety (16 per cent).
Major neurological conditions occurred more rarely, such as ischaemic stroke seen in 1.9 per cent of cases in the data set, haemorrhagic stroke (0.4 per cent) and seizure (0.06 per cent).
People with severe covid-19 were overrepresented in the data set, as most of the studies focused on those admitted to hospital, and even the studies of people outside hospitals included few with very mild or no symptoms.
However, the study found that among people with symptomatic acute covid-19 who weren’t admitted to hospital, neurological symptoms were still common.
In this group, 55 per cent reported fatigue, 52 per cent loss of smell, 47 per cent muscle pain, 45 per cent loss of taste and 44 per cent reported headaches.
The researchers said it is possible that such symptoms are just as common in severe cases, as mild symptoms might not be reported by a patient in critical care.
While the review didn’t investigate causal mechanisms, the researchers suggested a few possible explanations, including inflammation or impaired oxygen delivery to the brain.
Psychosocial factors relating to the context of the global pandemic may also play a role, the researchers said. This might be because people who are acutely ill may feel isolated when they cannot see their family or friends, which may explain why depression and anxiety have been found in some studies of people with covid-19 to be more common than in other viral illnesses such as the flu.
“With millions of people infected globally, even the rarer symptoms could affect substantially more people than in usual times,” said Alasdair Rooney at the University of Edinburgh, UK, a co-author of the study. “Mental health services and neurological rehabilitation services should be resourced for an increase in referrals.”
Journal reference: Journal of Neurology, Neurosurgery and Psychiatry, DOI: 10.1136/jnnp-2021-326405
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