Abstract
Background: The prevalence of mental disorders, particularly anxiety and depression, has been increasing and is becoming a major public health concern in Portugal. Digital mental health solutions offer scalable and accessible tools for monitoring and managing mental health. 'P5 Mental Health' has been created as a platform to assess and monitor symptoms of anxiety and depression in the Portuguese population, and to offer strategies to promote well-being to support users. Objective: This study aims to (1) describe the P5 Mental Health platform, (2) evaluate its feasibility as a digital mental health monitoring tool, and (3) analyze trends in the prevalence and severity of anxiety and depression symptoms over a four-year period, particularly in response to major societal stressors. Methods: Between September 2020 and September 2024, 46,032 responses were collected from platform users. Anxiety and depression symptoms were assessed using the Generalized Anxiety Disorder-7 (GAD-7) and Patient Health Questionnaire-9 (PHQ-9) scales. Longitudinal trends were analyzed across four time periods. Welch's ANOVA and Games-Howell post hoc tests were conducted to compare symptom severity across time, and ordinal logistic regression was used to examine the impact of time on symptom progression. Results: Anxiety and depression symptoms increased between 2020 and 2022, stabilized thereafter, and showed a slight decline in 2024. The proportion of users reporting moderate to severe anxiety (GAD-7 ≥ 10) rose from 30.87% in September 2020 to 66.30% in June 2022. Similarly, the prevalence of moderate to severe depressive symptoms (PHQ-9 ≥ 10) rose from 3.62% in March 2021 to 51.54% in August 2021. Despite a small decrease in 2024, symptom levels remained significantly higher than baseline levels recorded at the beginning (p < 0.001). A strong positive correlation was found between anxiety and depression symptoms (r = 0.739, p < 0.001), underscoring their high comorbidity. Conclusions: This study demonstrates the feasibility of the P5 Mental Health platform as a real-time mental health monitoring tool, particularly during periods of heightened social and economic stress. The findings highlight the need for sustained digital mental health interventions beyond crisis periods to ensure long-term engagement; however, future improvements should focus on increasing user engagement and adding personalized features to ensure long-term mental health management.