TORONTO -- A new study suggests that some COVID-19 patients who suffer from prolonged symptoms after recovery, including anxiety, mood disorders, sleep problems and fatigue, are at a greater risk for depression.

The study, conducted by researchers at Massachusetts General Hospital in Boston, found that those who suffered long-term mental and neurological symptoms after acute infection with SARS-CoV-2, the virus that causes COVID-19, have an increased chance of becoming depressed.

Researchers reported that depressive symptoms were more prevalent in younger patients and among men, as well as among those with a greater severity of COVID-19 infection.

However, The researchers say their study does not weigh in on whether COVID-19 caused the depressive symptoms or vice-versa. They say it only shows that the two seem to go hand-in-hand for some patients.

The findings were published Friday in the .

The study looked at more than 3,900 Americans with prior COVID-19 illness surveyed through online questionnaires between May 2020 and January 2021.

According to the study, the monthly questionnaires asked participants standard sociodemographic questions, including race and ethnicity, in addition to whether they had been diagnosed with COVID-19 or received a positive test result, and in which months they had symptoms.

These individuals were also asked to indicate the presence or absence of specific symptoms and overall severity of COVID-19 infection. The participants also completed a screen for symptoms of depression with those scoring higher than 10 considered to be suffering from depressive symptoms.

Of those surveyed, researchers found that 2,046 participants (52.4 per cent) had "moderate or greater symptoms of major depression."

"Our results add to a growing body of evidence suggesting the importance of considering potential neuropsychiatric sequelae of COVID-19 infection. Our results also suggest the importance of considering strategies that might mitigate the elevated risk of depressive symptoms following acute infection," the study's authors wrote.

According to the study, the average age of participants was 38 years old with the average length of time since initial COVID-19 symptoms being four months.

The study also found that those who reported headaches with COVID-19 infection, as well as those who had greater overall severity of infection, appeared to have an "elevated risk of depressive symptoms."

However, the authors acknowledged that they could not exclude the possibility that individuals with current depression are more likely to report headaches.

Researchers noted that the study did not look at whether the loss of smell and taste were linked to increased anxiety and depression, only headaches.

"We might similarly expect other symptoms to also be reported more frequently, but this was not generally the case," the study's authors wrote.