Fidelity of implementation of Reptes, an alcohol and cannabis selective prevention program for youngsters Noelia Vázquez; Xavier Continente; Montse Bartroli; Olga Juárez; Laura Muñoz; Francesca Sánchez-Martínez; Anna Pérez; Carles Ariza;

Urban and social determinants of alcohol and tobacco consumption among adolescents in Madrid Maitane Berasaluce; Irene Martín-Turrero; Roberto Valiente; Lucía Martínez-Manrique; María Sandín-Vázquez; Xisca Sureda;

Mobility restrictions and mental health among young adults during the COVID-19 pandemic in Ecuador Tannia Valeria Carpio-Arias; Jefferson Santiago Piedra-Andrade; Tomás Marcelo Nicolalde-Cifuentes; María Victoria Padilla-Samaniego; Estephany Carolina Tapia-Veloz; María Fernanda Vinueza-Veloz;