The first year of the COVID-19 pandemic appears to have taken a relatively limited toll on overall global mental health, Canadian researchers say in a new study published in the British Medical Journal.

Researchers reviewed 137 studies from around the world that measured people's overall mental health, as well as depression and anxiety levels, before the pandemic and then again during 2020.

They were surprised to find that there was minimal overall change at a population level.

Senior author Dr. Brett Thombs, a researcher at McGill University, said that coverage of the pandemic has mostly focused on snapshots of people whose mental health has deteriorated and people have generalized that to the overall population.

The majority of studies during COVID-19 have not looked at how the participants were faring mentally prior to the pandemic, he said, so they wouldn't have been able to measure changes in mental health, either positive or negative.

”Different individuals have had different experiences with mental health and COVID," Thombs said.

"It's been all over the place — some terrible, some positive, some hasn't changed much. But overall, you know, there's been a lot of resilience here and there's a lot of good news in that respect.”

The study challenges media portrayals of mental health decline as "a tsunami or catastrophe," Thombs said.

However, when the researchers looked at different subgroups by age, sex or gender, they did find that women's mental health worsened by a small amount, including anxiety and depression symptoms, during 2020.

Although the study didn't look at reasons for that decline, Thombs suggested it could be because women tended to shoulder more of the childcare burdens during lockdowns. In addition, more women were front-line workers in health and long-term care facilities that were devastated by COVID-19. Women may also have suffered domestic violence and abuse that appeared to increase during the pandemic.

Sarah Markham, a patient advocate in the U.K. who was also one of the study's co-authors, said the study gives "an overview at a large-scale population level," but "obviously within any population, there are going to be groups which are more vulnerable.”

Markham, who suffers from chronic depression herself, said that people with existing mental illnesses had varied experiences when the pandemic hit — and they weren't all negative.

“With mental health difficulty can come, in time, greater mental health resilience,” she said.

“If (you’re) living with a mental health disorder, you develop an awful lot of resilience through having to manage it and live with it and fight to have a good life," Markham said.

"Very often, that can make you stronger, mentally more resilient to a massive change or a massive threat like COVID because you’ve dealt with threats throughout your entire life."

Conversely, if someone was just starting to deal with symptoms of mental illness without the proper coping skills, they may have struggled more, she said.

The authors acknowledged limitations in their study, and suggested caution in interpreting the results.

"This paper only analyzed data from trials involving the same participants before and during the pandemic, which may have excluded data from other types of studies,” said co-author Dr. Sanjeev Sockalingam, physician-in-chief and a clinician scientist at the Centre for Addiction and Mental Health, in a news release.

“A limited number of studies were from low- or middle-income countries, only a few studies had data from late 2020 and no studies reported on long-term mental health outcomes related to COVID-19. In other words, this research doesn’t necessarily give us the full picture of how everyone fared in the pandemic,” Sockalingam said.

There were very few Canadian studies that met the criteria to be included in the review, Thombs said. But the majority of the research was from middle and high-income countries and there's no reason to think the findings wouldn't apply in Canada, he said.

This report by The Canadian Press was first published March 9, 2023.

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