Efficacy and Safety of Intranasal Esketamine in Treatment-Resistant Depression with Comorbid Autism Spectrum Disorder: Three Case Reports.

Major depressive disorder (MDD) is a leading cause of disability worldwide and contributes significantly to the global burden of disease. Recent data show an increasing prevalence of treatment-resistant depression (TRD). Patients with autism spectrum disorder (ASD) often exhibit MDD as a comorbidity and it is often resistant to conventional treatments. ASD determines emotional dysregulation and a reduced ability to understand mental states (mentalization). These features can lead to suicidal ideation and/or behavior. Intranasal esketamine may offer a novel therapeutic option for this population. This case series focuses on the clinical response to intranasal esketamine in patients with autism and TRD; esketamine is approved in Italy as an add-on therapy in TRD, so our case study is based on an in-label treatment. Three young patients (n = 3, F/M 2:1, age range 20-25 y) with light to moderate autism (Level 1 or 2) were treated. Esketamine was administered in augmentation with selective serotonin reuptake inhibitors (SSRIs) or serotonin-norepinephrine reuptake inhibitors (SNRIs) in accordance with EMA/AIFA guidelines. A structured follow-up protocol was set to monitor depressive symptoms, social cognition, and mentalization. Follow-up during treatment was maintained for six months, and psychometric evaluations were performed at six time points: baseline (T0), 1 week (T1), 1 month (T2), 2 months (T3), 3 months (T4), and 6 months (T5). Also, subjective quality of life was investigated before and after the observation period. Despite differences in clinical profile, all patients showed good efficacy of esketamine in reducing depressive symptoms: two patients experienced clinical remission at T5 (MADRS < 10), one patient showed partial response (dMADRS = 43.24%). No major side effects were reported. Significant improvements were observed after the first week of treatment (P1: MADRS_T0 = 37, MADRS_T1 = 12; P2: MADRS_T0 = 32, MADRS_T1 = 21; P3: MADRS_T0 = 25, MADRS_T1 = 12). Depressive relapses occurred (e.g., P1, T3-T4), but they were not associated with hospitalizations and/or suicidal attempts. Suicidal ideation, when present, decreased by the end of the follow-up period. Lack of mentalization and in social cognition was noted, with just mild improvements during therapy. Subjective quality of life improved significantly for all patients (P1: 28% at T0, 73% at T5. P2: 25% at T0, 71% at T5. P3: 35% at T0, 80% at T5). Intranasal esketamine showed a favorable efficacy and safety in these three cases of TRD in comorbidity with ASD (at six months: total remission = 66.66%, partial remission = 33.33%, inefficacy = 0%, drop-out = 0, severe adverse events = 0). Besides improvements in depressive symptoms, esketamine was associated with a constant decrease in suicidal thoughts. A case series is unfit to form statistical conclusions; preliminary data warrant further investigation in randomized controlled studies to validate the therapeutic potential of esketamine in this population.