London, Mar 15 (PTI) Serious COVID-19 illness is associated with an increased risk of long-term adverse mental health outcomes, according to a study published in The Lancet Public Health journal.

The researchers found that hospitalised patients with a SARS-CoV-2 infection were more likely to experience depressive symptoms up to 16 months after diagnosis compared to those never infected.

Patients who were bedridden for seven days or more had higher rates of depression and anxiety, compared to those diagnosed with COVID-19 but never bedridden, they said.

The study found that symptoms of depression and anxiety mostly subsided within two months for non-hospitalised patients with COVID-19.

However, patients who were bedridden for seven days or more remained at increased risk of depression and anxiety over the 16-month study period.

The researchers looked at symptom-prevalence of depression, anxiety, COVID-19 related distress, and poor sleep quality among people with and without a diagnosis of COVID-19 from 0-16 months.

The analysis drew upon data from seven groups across Denmark, Estonia, Iceland, Norway, Sweden, and the UK.

Of the 247,249 people included, 9,979 (4 per cent) were diagnosed with COVID-19 between February 2020 and August 2021.

Overall, participants diagnosed with COVID-19 had a higher prevalence of depression and poorer sleep quality compared to individuals who were never diagnosed.

'Our research is among the first to explore mental health symptoms after a serious COVID-19 illness in the general population up to 16 months after diagnosis,' said study author Unnur Anna Valdimarsdottir, a professor at the University of Iceland.

'It suggests that mental health effects are not equal for all COVID-19 patients and that time spent bedridden is a key factor in determining the severity of the impacts on mental health,' Valdimarsdottir said.

The researchers noted that quicker recovery of physical COVID-19 symptoms may explain in part why mental health symptoms decline at a similar rate for those with a mild infection.

However, patients with severe COVID-19 often experience inflammation which has previously been linked to chronic mental health effects, particularly depression, they said.

'The higher occurrence of depression and anxiety among patients with COVID-19 who spent seven days or longer bedridden could be due to a combination of worrying about long-term health effects as well as the persistence of physical long COVID symptoms well beyond the illness,' said study co-author Ingibjorg Magnusdottir, from the University of Iceland.

'Equally, inflammatory responses among patients with a severe diagnosis may contribute to more persistent mental health symptoms,' Magnusdottir said.

In contrast, the researchers said, the fact that individuals with a mild COVID-19 infection can return to normal lives sooner and only experience a benign infection likely contributes to the lower risk of negative mental health effects observed.

The authors acknowledged several limitations in the study.

First, individuals diagnosed with COVID-19 were slightly more likely to have past diagnoses of psychiatric disorders than individuals without disease diagnosis, the researchers said.

However, the absolute differences in the history of psychiatric disorders never exceeded 4 per cent in any of the groups and did not impact the interpretation of the findings, they said.

Second, the study reflects self-reported data of COVID-19 diagnosis and mental health effects - the coexistence of two or more conditions - that are interrelated to some extent, the researchers said.

Third, most of the comparison group responded between April and June 2020, and responses from COVID-19 patients were accumulated between April 2020 and August 2021, they said.

(This story has been published from a wire agency feed without modifications to the text. Only the headline has been changed.)