Children who started secondary school in 2021 were more likely to report increased symptoms of depression than those starting Year 7 before the pandemic, a study has found.
Responses to a student health and wellbeing survey revealed 21% of starters last year reported increased depression symptoms compared to 15% in 2019.
The survey involved 120,000 11-to-16-year-olds from 202 schools in Wales and the data was analysed by researchers at Cardiff University.
Dr Nicholas Page, who led the study, said: "Transitioning to secondary school is a period of potentially heightened stress and anxiety, and this finding could suggest that such feelings were further elevated for young people in Wales who started secondary school in 2021, following the disruption of the pandemic."
The analysis also showed an overall increase in the percentage of children aged 11 to 16 reporting elevated symptoms of depression in 2021, the number rising from 24% to 28%.
The research suggested the rise was driven by increased rates among girls and gender non-binary students, as the level of schoolboys reporting depression symptoms did not change.
It was children in Year 11 who had the highest prevalence of mental health difficulties compared to other year groups. 36% of the oldest secondary school year respondents reported elevated symptoms of depression in 2021, up from 33% in 2019.
Professor Simon Murphy, director of the Centre for Development, Evaluation, Complexity and Implementation in Public Health Improvement, said: "These results, gathered before and 18 months since the beginning of the pandemic, provide important insights regarding changes in young people's mental health and wellbeing during this time.
"While it is not possible to say whether declines in young people's mental health are due to the pandemic or a general trend, it will be important to continue to monitor these indicators to aid Covid-19 recovery efforts in Wales."