{Reference Type}: Journal Article {Title}: New-onset schizophrenia in an adolescent after COVID-19. {Author}: Ishii M;Nakajima-Ohyama KC;Saito H;Ohya T;Uchiyama S;Takahashi M;Sakamaki M;Watanabe A;Inoue JI;Sekine T;Tateno A;Kishi Y; {Journal}: J Nippon Med Sch {Volume}: 0 {Issue}: 0 {Year}: 2024 Jun 18 {Factor}: 1.115 {DOI}: 10.1272/jnms.JNMS.2025_92-301 {Abstract}: Schizophrenia develops during adolescence. Maternal infections during the fetal period increase the incidence of schizophrenia in children, which suggests that the pathogenesis involves neuroinflammation. Here, we report a case of new-onset schizophrenia in a 16-year-old boy after COVID-19. After developing COVID-19, he entered a catatonic state 4 days later and was hospitalized. Benzodiazepines alleviated his catatonia, but hallucinations and delusions persisted. Encephalitis and epilepsy were excluded by magnetic resonance imaging (MRI), encephalography, and cerebrospinal fluid examination. Psychosis persisted after the virus titer declined and the inflammatory response subsided. Moreover, the patient exhibited delusions of control-a Schneider's first-rank symptom. Schizophrenia was diagnosed, and olanzapine improved his symptoms. He had a brief history of insomnia before COVID-19 but his symptoms did not satisfy the ultra-high-risk criteria. However, COVID-19 may have facilitated development of schizophrenia through neuroinflammation and volume reduction in the gray matter of the right medial temporal lobe. This case demonstrates that infectious diseases in adolescents should be carefully managed, to prevent schizophrenia.