Meta-Analysis: Glutamatergic Agents May Improve Obsessive-Compulsive and Related Disorder Symptoms

Background: Obsessive-compulsive and related disorders (OCRDs) affect approximately 2% to 3% of the general population and encompass conditions such as OCD, skin-picking disorder, and trichotillomania, leading to substantial distress and impaired daily functioning. Glutamatergic dysfunction within cortico-striatal-thalamo-cortical circuits has emerged as a potential target, prompting investigations into whether glutamatergic agents can enhance outcomes either alone or alongside selective serotonin reuptake inhibitors (SSRIs).

Objective: To determine whether glutamatergic medications, used as monotherapy or as augmentation to SSRIs, can improve clinical symptoms across different OCRDs compared to placebo, with emphasis on changes in standardized measures such as the Yale-Brown Obsessive Compulsive Scale (Y-BOCS).

Methods: This systematic review and meta-analysis included 27 double-blind, placebo-controlled randomized clinical trials involving 1369 participants with OCRDs. Eligible studies examined agents including N-acetylcysteine (NAC), memantine, lamotrigine, riluzole, and topiramate, among others. Data extraction focused on changes in symptom severity, and pooled effect sizes were calculated using random-effects meta-analysis. Subgroup analyses evaluated potential moderators, such as disorder subtype, age group, refractoriness, and augmentation strategies, while sensitivity analyses and publication bias assessments (e.g. Egger test) were performed to ensure robustness.

Results: Overall, glutamatergic medications showed a large effect size in reducing OCRD symptoms (Cohen’s d = −0.80). Specifically for OCD (n=23 trials), a significant mean reduction in Y-BOCS scores (−4.17 points) indicated clinically meaningful improvement. Publication bias was detected in the broader OCRD meta-analysis but not in the OCD-specific analysis. Heterogeneity was high across studies, reflecting varied populations and treatment designs. Despite these findings, the certainty of evidence ranged from low to moderate, mandating cautious interpretation.

Conclusions: Glutamatergic interventions appear promising for OCRDs, particularly OCD, where moderate-certainty evidence suggests meaningful symptom improvement. Nevertheless, elevated heterogeneity and signs of publication bias highlight the need for larger, more rigorous trials to confirm optimal dosing parameters and elucidate which patient subsets may benefit most.

Implications for Practice: Clinicians might consider adding or switching to glutamatergic agents for individuals with inadequate response to SSRIs. However, these findings do not warrant unrestrained enthusiasm. Each case should be weighed individually, taking into account possible mild to moderate gastrointestinal side effects (particularly with NAC).

Study Strengths and Limitations: Strengths include the focus on double-blind RCTs, diverse glutamatergic agents, and robust statistical approaches. Limitations comprise high between-study heterogeneity, limited data for less common disorders (e.g., body dysmorphic disorder), and potential publication bias. Additionally, few trials specifically tested novel agents like ketamine.

Future Research: Studies with larger sample sizes, clearly defined outcomes, and detailed dose-response evaluations are needed. Future trials should explore underrepresented OCRDs, such as hoarding disorder, and newer glutamatergic compounds (e.g., troriluzole) to further optimize therapeutic strategies.

Reference: Coelho DRA, Yang C, Suriaga A, et al. Glutamatergic Medications for Obsessive-Compulsive and Related Disorders: A Systematic Review and Meta-Analysis. JAMA Netw Open. 2025;8(1):e2452963. DOI: http://doi.org/10.1001/jamanetworkopen.2024.52963