Background Despite the impact that the COVID‐19 pandemic had on adolescents' mental health, there is a lack of studies comparing it pre‐ and postpandemic using consistent designs and measurements. Therefore, this study aimed to analyze changes in adolescent psychopathology, deliberate self‐harm behavior, substance use, and help‐seeking behavior pre‐ and post‐COVID‐19, with an identical study design. Methods The study included three repeated cross‐sectional studies conducted in 2014, 2018, and 2023, including self‐reported data from Finnish secondary school students in grades 7 to 9, aged 13 to 16 ( n = 9,024). The survey measured demographic information, mental health using the Strengths and Difficulties Questionnaire (SDQ), deliberate self‐harm behavior, substance use, and help‐seeking behavior. Results Comparing data in 2023 with 2018, there were significant increases among females in total SDQ score (OR 2.1, 98.33% CI 1.7–2.7), conduct problems (OR 1.7, 98.33% CI 1.1–2.7), emotional symptoms (OR 1.8, 98.33% CI 1.5–2.3), and hyperactivity symptoms (OR 2.8, 98.33% CI 2.2–3.6). Perceived severe overall difficulties (OR 2.8, 98.33% CI 2.0–3.7), weekly smoking (OR 2.7, 98.33% CI 1.5–4.9), and seeking help (OR 1.5, 98.33% CI 1.2–2.0) increased. For males, increases were noted only in hyperactivity symptoms (OR 2.5, 98.33% CI 1.2–1.9) and perceived severe overall difficulties (OR 1.5, 98.33% CI 1.0–2.1), along with a decrease in alcohol consumption (OR 0.7, 98.33% CI 0.5–0.9). By contrast, the period from 2014 to 2018 showed minimal changes. Conclusion The concerning rise in psychopathology after the COVID‐19 pandemic, particularly among females, highlights the importance of early detection and effective interventions.
Sourander et al. (2025) studied this question.