The COVID-19 pandemic has had a long-lasting impact on the mental health and substance use among adolescents, according to a study published in The Lancet Child & Adolescent Health journal.

The research is based on survey responses from a nationwide sample of over 64,000 13–18-year-old North American and Icelandic adolescents assessed prior to and up to two years into the pandemic.

Researchers at Columbia University in the US and colleagues had in a 2021 study found an increase in depressive symptoms and decrease in mental well-being among 13–18-year-old adolescents within one year of the global spread of the COVID-19 pandemic.

A decline in substance use, in particular cigarette smoking, e-cigarette use and alcohol intoxication, was also observed.

Expanding on these findings, the new study shows that the negative effect on adolescent mental health persisted up to two years into the pandemic.

"It is worrisome that we still see an increase in mental health problems among adolescents two years into the pandemic. And this is occurring despite social restrictions having been eased in Iceland," said Thorhildur Halldorsdottir, an assistant professor at Reykjavik University in Iceland, and senior author of the study.

The initial decrease in cigarette smoking and e-cigarette use observed shortly after the arrival of the pandemic was also maintained up to two years into the pandemic, the researchers said.

However, the frequency of adolescent alcohol intoxication appeared to be returning to pre-pandemic levels, they said.

"It is of course positive to see that the reduction in cigarette smoking and vaping has been maintained," said Ingibjorg Eva Thorisdottir, chief data analyst at Iceland-based research consultancy Planet Youth, and lead author of the study.

"We will need to monitor alcohol intoxication among adolescents in years to come, especially given the increase in mental health problems," Thorisdottir said.

The study also examined the association of immigration status, residency, parental social support and nightly sleep duration with adolescent mental health and substance use.

Parental social support and an average of 8 hours or more of sleep per night was associated with better mental health and less substance use among adolescents, the researchers said.

The relationship between immigration status and residency with adolescent mental health was less clear, they said.

These findings suggest that stress exposure, like the COVID-19 pandemic, affects all adolescents to some extent rather than only vulnerable subgroups.

"Policymakers should consider implementing large-scale evidence-based prevention efforts focusing on depressive symptoms to mitigate the negative effect of the pandemic," said John Allegrante, a professor at Columbia University, and a senior collaborating investigator on the study.

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