**1. Introduction**

The vulnerabilities associated with the pandemic of COVID-19 have motivated studies reflecting on adolescents, including their physical and psychological health, either through their research or systematic analysis of documents produced by educational and health institutions and researchers [1–6].

There is an agreement in the research about the psychosocial effects of the COVID-19 pandemic on school-aged children and adolescents [7]. Young people reported feeling more lonely and having more depression and anxiety symptoms [8]. Quantitative studies done all over Europe [9–12] confirm this link and show an increase in symptoms of depression, anxiety, and stress.

Tomé and colleagues [13] argue that given the contingencies grounded in the pandemic by COVID-19 (more specifically, social distancing and general confinement/ lockdown of the population), young people's psychosocial contexts are considered to have undergone changes that, in turn, generated risks to their psychological health and life satisfaction [3, 10, 12, 14, 15].

The Dual Factor Model [16–18], was used, with some adaptations for its use in population studies, to understand the psychological health of children and adolescents and the associations with their lives and well-being. This model is here referred as "the quadripartite model", as we retained from this model that life satisfaction and psychological symptoms are not opposed in a continuum of two dimensions, but rather four psychological states: Complete Psychological Health (reduced psychological symptoms and high life satisfaction), Incomplete Psychological Health (reduced psychological symptoms and low life satisfaction), Incomplete Psychological Distress (marked psychological symptoms and increased life satisfaction), and Complete Psychological Distress (marked psychological symptoms and low life satisfaction). Complete Psychological Health implies both conditions: high life satisfaction and reduced psychological symptoms, as suggested in the Dual Factor Model [16–18].

To test this model, data from two national studies, the Directorate-General of Education and Science Statistics of the Ministry of Education and the Ministry of Science (DGEEC), and the Health Behaviour in School-aged Children (HBSC) studies, were used for specific analyses. Gender and grade differences (a proxy for age differences) were confirmed in the four groups (complete and incomplete, health and distress). The DGEEC study also analysed how the situation changes with the perception of quality of life and three health behaviours/lifestyles. Considering HBSC, the differences between the 2018 wave (pre-COVID-19 pandemic) and the 2022 wave (post-COVID-19 pandemic) were analysed.
