“…There have been several previous studies using epidemiological or non-treatment seeking samples that have reported data on longitudinal trajectories of mental health, as well as the relationship of various demographic factors relevant to understanding mental health among youth. In terms of age-related differences in mental health, there is consistent evidence from studies in both the United States, Canada and Europe that levels of depression tend to increase from school age into adolescence ( Strohschein, 2005 , Van Oort and Greaves-Lord, 2009 , Robbers and Bartels, 2010 , Ormel and Oldehinkel, 2012 , Ferro and Gorter, 2015 , Coley and O'Brien, 2019 , Antolin-Suarez and Nieto-Casado, 2020 ), with evidence that this increase is greater in females than males ( Bongers et al, 2003 ). Patterns for anxiety are more mixed, with some evidence for decreases in various forms of anxiety from school age to adolescence ( Van Oort and Greaves-Lord, 2009 , Ormel and Oldehinkel, 2012 ).…”