Case report of S-ketamine as treatment option for suicidal ideation and treatment-resistant depression in adolescents with early-onset psychosis

Background: Depressive symptoms and suicidality are highly prevalent in adolescents with early-onset psychosis (EOP) and often remain refractory to standard treatment. While S‑ketamine is an established treatment for treatment-resistant depression in adults (TRD), its use in primary psychotic disorders remains scarce due to risk of exacerbation of psychotic symptoms. CASE PRESENTATION: We present the case of a 16-year-old male with schizophrenia (ICD-10: F20.9) and chronic suicidality. Despite achieving remission of positive symptoms with amisulpride, severe depressive symptoms including suicidality persisted. Following the initiation of off-label intranasal S‑ketamine (titrated to 84 mg) at age 17 and 11 months, the patient showed a rapid clinical response. The Montgomery-Åsberg Depression Rating Scale (MADRS) score decreased by 50% within 3 weeks, accompanied by a significant reduction in the Positive and Negative Syndrome Scale (PANSS)-positive symptoms subscale score (from 22 to 10) and the PANSS-negative symptoms subscale score (from 33 to 17). Notably, no exacerbation of remitted positive symptoms occurred, and sustained functional recovery was achieved.

Conclusion: This case suggests that intranasal S‑ketamine may be a safe and effective augmentation strategy for TRD and suicidality in stable adolescent early-onset psychosis, highlighting the need for further research in this high-risk population.