People who endure a headache with the coronavirus may be more at risk of depression down the line, research suggests.
Early in the pandemic, experts warned the infectious outbreak could have a "profound" and "pervasive" impact on people's mental health for some time.
Initially considered a respiratory infection, the coronavirus is now known to affect many parts of the body. Its impact on the vital organ is evidenced by some patients enduring brain fog, fatigue and a loss of taste or smell.
The NHS does not recognise headaches as a "main" symptom of the coronavirus, however, the World Health Organization states they can be a "less common" sign of the infection.
After analysing more than 3,900 adults who had overcome the coronavirus, medics from Massachusetts General Hospital found enduring a headache with the infection was linked to a 33% increased risk of later having depression.
The Massachusetts medics analysed former coronavirus patients – average age 38 – who took part in eight "waves" of an internet survey between June 2020 and January 2021.
More than half (52%) of the participants "met the criteria for symptoms of major depressive disorder".
The "presence of headache" while infected was linked to a 33% increased risk of "moderate or greater depression symptoms".
"Greater overall severity" of the coronavirus itself was also associated with more than double the odds of enduring the mental health condition.
The female participants were less likely to have depression, with the risk also decreasing with age.
The medics have stressed some of the participants may have had the mental health condition beforehand, which could have made them more susceptible to headaches with the coronavirus.
"Nevertheless, our results add to a growing body of evidence suggesting the importance of considering potential neuropsychiatric sequelae of COVID-19 [the disease caused by the coronavirus] infection," they wrote in the journal JAMA Network Open.
"Our results also suggest the importance of considering strategies that might mitigate the elevated risk of depressive symptoms following acute infection."
Watch: How coronavirus can affect the brain
The circulating coronavirus is one of seven strains of a virus class that are known to infect humans.
It is genetically similar to fellow-strain severe acute respiratory syndrome (Sars), which killed 774 people during its 2002/3 outbreak.
Sars has been described as "clinically neurotoxic, causing mental health and neurological disorders".
Although unclear, the circulating coronavirus could have "persistent direct neurotoxic effects and immune-mediated neurotoxic effects on the brain".
The Sars outbreak was linked to a 30% increase in suicide in those aged 65 or over, while half (50%) of the recovered patients "remained anxious".
Experts have stressed, however, a depression epidemic does not have to be an inevitable outcome of the pandemic, with lessons being learnt from the Sars outbreak.
It is unclear exactly how the coronavirus affects the brain. Evidence suggests the infection may directly enter the vital organ. The immune system may also trigger damaging inflammation in response to the pathogen.
For confidential emotional support at times of distress, contact The Samaritans at any time by calling 116 123 or emailing firstname.lastname@example.org.
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