COVID-19 is associated with an increased risk of mental health disorders, including anxiety, depression, substance use, and sleep disorders, up to one year after the viral infection, according to a US study. The findings, published in The BMJ on Wednesday, suggest that tackling mental health disorders among survivors of COVID-19 should be a priority.

More than 403 million people globally and 77 million in the US have been infected with the virus since the pandemic started.”To put this in perspective, COVID-19 infections likely have contributed to more than 14.8 million new cases of mental health disorders worldwide and 2.8 million in the U.S,” said senior author of the study Ziyad Al-Aly, referring to data from the study.

“Our calculations do not account for the untold number of people, likely in the millions, who suffer in silence due to mental health stigma or a lack of resources or support,” Al-Aly, a clinical epidemiologist at Washington University, said.The researchers used data from the US Department of Veterans Affairs national healthcare databases to estimate the risks of mental health outcomes in people who survived at least 30 days after a positive PCR test result between March 2020 and January 2021.

They compared mental health outcomes in the COVID-19 dataset with two other groups of people not infected with the virus: a control group of more than 5.6 million patients who did not have COVID-19 during the same time frame; and a control group of over 5.8 million patients from March 2018 through January 2019, well before the pandemic began.The majority of study participants were older white males.However, because of its large size, the study included more than 1.3 million females, more than 2.1 million Black participants, and large numbers of people of various ages.

The COVID-19 group was further divided into those who were or were not admitted to hospital during the acute phase of infection.Information was also collected on potentially influential factors including age, race, sex, lifestyle, and medical history.The researchers then followed all three groups for one year to estimate the risks of prespecified mental health outcomes, including anxiety, depression and stress disorders, substance use disorders, neurocognitive decline, and sleep disorders.

Compared with the non-infected control group, people with COVID-19 showed a 60 per cent higher risk of any mental health diagnosis or prescription at one year. When the researchers examined mental health disorders separately, they found that COVID-19 was associated with an additional 24 per 1,000 people with sleep disorders at one year, 15 per 1,000 with depressive disorders, 11 per 1,000 with neurocognitive decline, and 4 per 1,000 with any substance use disorders.Similar results were found when the COVID-19 group was compared with the historical control group.The risks were highest in people admitted to hospital during the initial phase of COVID-19, but were evident even among those who were not admitted to hospital.

People with COVID-19 also showed higher risks of mental health disorders than those with seasonal influenza, the researchers said.Those admitted to hospital for COVID-19 showed increased risks of mental health disorders compared with those admitted to hospital for any other reason, they said.The researchers cautioned that this is is an observational study, so cannot establish cause, while acknowledging that some misclassification bias may have occurred.

The study included mostly older white men, so results may not apply to other groups, they added.The research suggests that people who survive the acute phase of COVID-19 are at increased risk of an array of incident mental health disorders, and that tackling mental health disorders among survivors of the disease should be a priority.