Neurochemicals measured by ¹H-MR spectroscopy: putative vulnerability biomarkers for obsessive compulsive disorder

Abstract

Object: Obsessive compulsive disorder (OCD) is the fourth most common psychiatric disorder characterized by recurrent, intrusive thoughts and repetitive, ritualistic behaviors that are debilitating to the patient. Despite its high prevalence and the attendant morbidity, the pathophysiology of OCD remains unclear. Magnetic resonance spectroscopy (MRS) provides a noninvasive method to characterize the molecular biochemistry that may contribute to the pathophysiology of OCD. This study aimed to identify alterations in neurochemical measures that are specific to OCD using in vivo proton (¹H) MRS of the caudate nucleus, anterior cingulate cortex, and medial thalamus in these patients, and to identify their role as vulnerability markers by comparing them with the healthy first degree relatives of these patients and healthy controls. Materials and methods: Appropriate psychometric instruments were applied in the study population followed by ¹H- MRS. The absolute neurochemical measures were quantified using a linear combination model. Results: Significant differences in neurochemical measures were demonstrated in two of the three candidate regions (except the medial thalamus) between the three study groups. Conclusions: Our results lend support to the neurodegenerative hypothesis of OCD, and also raise the possibility of exploring these neurochemical measures (as measured by MRS) as putative vulnerability biomarkers in OCD that may aid in early identification and devising early prevention or management strategies for the population vulnerable to OCD.