Adolescents Hospitalized in an Acute Psychiatric Ward: The Difference between Males and Females in the Pre- and Pandemic/Post-Pandemic Periods

(1) Background: The pandemic lowered by 10% the psychological wellness among adolescents worldwide. (2) Methods: This observational retrospective study compared the demographic and clinical variables of male and female adolescents hospitalized in an acute psychiatric ward during the pre-pandemic, from 1 July 2017 to 28 February 2020, and the pandemic/post-pandemic, from 1 March 2020 to 30 June 2023. (3) Results: In total, 153 adolescents of 15.8 years on average (±1.14 DS) were more frequently hospitalized (n = 131, 54.4%) in the pre-pandemic than in the pandemic/postpandemic (n = 110, 45.6%), but female hospitalizations increased in the post-pandemic more than male hospitalizations (62.9% vs. 37.1%) (Pearson Chi2 = 8.54, p = 0.003); in the pandemic/post-pandemic, we reported increased aggressive behavior and schizophrenia spectrum and emotional disorders in males, whereas in females, depressive and emotional disorders were prevalent; more adolescents previously treated in Child Mental Health Services were hospitalized in the pandemic/post-pandemic period; and males hospitalized in the study period reported higher Health of the Nation Outcome Scales for Children and Adolescents (HoNOSCA) scores. (4) Conclusions: In the pandemic/postpandemic, females more frequently required hospitalizations for depressive behavior and males for aggressive behavior and schizophrenia spectrum disorders, whereas, in both males and females, hospitalizations due to emotional disorders increased. Our results suggest the need for mental health prevention in adolescents, who represent the most vulnerable population in the case of disaster.