Neurobiological differences in early-onset obsessive-compulsive disorder: A study of the glutamatergic system based on functional magnetic resonance spectroscopy.

In this study, the combination of functional state magnetic resonance spectroscopy (fMRS) and cognitive tasks was used to conduct subgroup analyses on early-onset OCD (EO) and non-early-onset OCD (non-EO) and explore differences in the glutamatergic system and cognitive function among OCD subtypes. A total of 70 OCD and 30 healthy controls (HCs) underwent clinical evaluation and were subsequently divided into the EO or non-EO groups. Next, both resting and functional state MRS data were collected, with the anterior cingulate cortex (ACC) serving as the region of interest. Quantitative analysis of MRS data yielded precise neurometabolic concentrations, which were then statistically analyzed alongside inhibitory function, as measured by the Go-nogo task. The final analysis included 92 participants (22 EO-OCD, 41 non-EO OCD, and 29 HCs). EO-OCD patients had significantly higher Glx levels (p = 0.044) and lower GSH levels (p = 0.009) in the functional state compared to the non-EO group. Moreover, in the EO group, correlation analysis revealed a positive correlation between the functional state Glx levels and the average response time for errors in the nogo task (r = 0.526, p = 0.014). Additionally, resting-state GSH levels were positively correlated with total Y-BOCS scores (r = 0.854, p < 0.001). Overall, early-onset OCD may represent a distinct subtype that requires targeted interventions, as evidenced by the imbalance in the glutamatergic system observed in early-onset OCD patients. Additionally, in early-onset patients, Glx concentration during activation was related to cognitive impairment.