2026 ECNP Congress

PS01-1072

Prospective study of clinical predictors of outcome and response to treatment in obsessive-compulsive disorder: Barcelona child and adolescent OCD cohort

Luisa Lázaro — N. Rodriguez, A. Vigil-Pérez, B. García-Delgar, E. Moreno, M. Prime, S. Lera, E. Forcadell, E. Pujal, P. Molina, A.E. Ortiz · Hospital Clinic of Barcelona, Department of Child and Adolescent Psychiatry and Psychology, Barcelona, Spain

2026 ECNP Congress

Objective: Patients with obsessive-compulsive disorder (OCD) benefit from therapies that have proven short term efficacy. However, the impact of these therapies on long-term functional recovery remains controversial and there is a clear need to identify the predictors and mechanisms of lingering symptomatology [1]. We aim to create a longitudinal cohort of 100 child and adolescent patients with OCD. Specific aims include characterizing the symptom course phenotype and identifying the clinical and neurobiological predictors and mechanisms of chronic symptoms.

Methods: Patients will be followed for 18 months and will undergo three functional neuroimaging assessments and baseline DNA genotyping. Ecological momentary assessment (weekly evaluations) will be used to discriminate groups of patients as a function of their symptom trajectories, and clinical differences across these groups will identify predictors of these trajectories. We will use a novel approach combining dynamic functional connectivity and polygenic risk scores to characterize both the neurobiological predictors and mechanisms of chronic symptoms. Following the baseline assessment, patients received naturalistic treatment, consisting of either psychopharmacological treatment in accordance with international clinical guidelines and/or intensive psychological treatment in the form of weekly cognitive behavioural therapy with exposure and response prevention, with a total of 14 sessions.

Results: To date, the study has been proposed to 77 patients with OCD, of whom 66 have agreed to participate in the longitudinal study. Of the 66 who underwent the baseline examination (V0), 47 participants completed the visit 1 (6 months), 32 participants completed the visit 2 (12 months) and 20 participants have completed the 18-month follow-up (V3). The mean age was 13.7 years at baseline [8.1-17.8], and 50 % were male. The mean baseline CY-BOCS score was 23.9. Mean CY-BOCS scores were 15.1 at visit 1, 12.6 at visit 2, and 13.4 at visit 3. Statistically significant differences were observed at first assessment compared to baseline (p<.001). A repeated-measures GLM showed a significant reduction in CY-BOCS total scores over the course of treatment, with significant linear and quadratic trends across assessments (F (3,110) =44.8, p<.001), indicating a clinically meaningful improvement in OCD symptom severity, with greater symptom reduction occurring at initial phases of treatment. A linear mixed-effects model with total CY-BOCS score as the dependent variable showed a significant main effect of visit (F(3,99.3) = 46.65, p < .001), indicating symptom reduction over time. No significant main effect of early-onset OCD (<12 vs ≥12 years) was found (F(1,47.4) = 1.94, p = .170). However, a significant visit × early-onset interaction emerged (F(3,99.3) = 4.51, p = .005), with early-onset patients showing less longitudinal improvement, suggesting a poorer treatment response.

Discussion: We report the preliminary findings from the first Spanish follow-up cohort of children and adolescents with OCD who underwent naturalistic psychopharmacological and/or psychological treatment. The results indicate clinically meaningful improvements that were sustained over time. More comprehensive analyses of the clinical, neuroimaging, and biomarker data, which will become available shortly, are expected to enable personalized treatment strategies and ultimately reduce rates of chronicity in this population.

Keywords: obsessive-compulsive disorder, child and adolescent, personalized treatment strategies

References

  1. Balachander S, Bakam A, Chakraborty S, Shidore M, Singh NA, Tholasappa V, Vijayakumar HG, Sharma L, Sharma E, Reddy YCJ, Arumugham SS. Clinical predictors of treatment resistance to serotonin reuptake inhibitors in obsessive-compulsive disorder: a meta-analysis. Expert Rev Neurother. 2026 Mar;26(3):301-309. doi: 10.1080/14737175.2025.2605084.