321. CHANGES IN BRAIN BIOCHEMICAL METABOLITES OF COGNITIVE FLEXIBILITY IMPAIRMENT IN NON-MEDICATED OBSESSIVE-COMPULSIVE DISORDER PATIENTS

Abstract Background Impairment of cognitive flexibility can be found in patients with currently severe obsessive-compulsive disorder (OCD). However, the imaging mechanisms underlying the decline in cognitive flexibility in OCD remain unclear. Aims & Objectives Currently, the mechanism behind OCD's impairment of cognitive flexibility is not well understood. Through 1H-MRS, this study aims to investigate the connection between the reduction in cognitive flexibility and brain biochemical metabolites in OCD patients. Method The study included 30 patients with untreated OCD (OCD group) and 29 healthy controls (HC). The Yale-Brown compulsion scale was used to score the obsessive-compulsive symptoms. Cognitive function was assessed using MCCB tests. The bilateral metabolic ratios of creatine (Cr) in prefrontal cortex (PFC), anterior cingulate cortex (ACC), pyramidal nucleus (LN) and thalamus were measured by 1H-MRS. Results The information processing speed, visual learning and total cognitive function were decreased in the OCD group compared with the HC group (p=0.007, 0.016, <0.001). NAA/Cr values in the left cingulate gyrus, right cingulate gyrus and right basal ganglia in OCD group were higher than those in HC group (p=0.003, <0.001, 0.017). However, the NAA/Cr value in the left thalamus was lower than that in the HC group (p=<0.001, 0.002). Discussion & Conclusions Changes in ACC, left thalamus and right basal ganglia are associated with cognitive flexibility impairment in obsessive-compulsive disorder patients.