399. ASSESSMENT OF RESTING STATE FUNCTIONAL MAGNETIC RESONANCE IMAGING (FMRI) CONNECTIVITY AMONG PATIENTS WITH MAJOR DEPRESSIVE DISORDER

Abstract Background Resting state functional connectivity analysis has a potential to unearth the putative neuronal underpinnings of various disorders of the brain. Major depressive disorder (MDD) has been regarded as a disorder arising out alterations in functional networks in the brain. Aims & Objectives There is paucity of literature on resting state functional MRI (Rs-fMRI) in major depressive disorder (MDD), especially from the Indian subcontinent. The purpose of our study was to elucidate the differences in Rs-fMRI connectivity between MDD patients and age and gender matched healthy controls (HC). Method In this prospective single-institute based study, the patients were recruited consecutively based on Hamilton depression rating scale (HAM-D). Age and gender matched healthy controls were also recruited. Rs-fMRI and anatomical MRI images were acquired for all the subjects (MDD and HC group) and subsequent analysis was done using the CONN toolbox. A total of 49 subjects were included in the final analysis (MDD = 28 patients, HC = 21 healthy controls). HAM-D score was noted to be 24.4±4.8 in the MDD group. There was no significant difference between MDD and HC groups as far as age, gender, employment status and level of education is concerned. Region-of-interest based analysis of Rs-fMRI data showed a significantly lower connectivity between the left insula and left nucleus accumbens and between left paracingulate gyrus and bilateral posterior middle temporal gyri in MDD group as compared to HC group. Results A total of 49 subjects were included in the final analysis (MDD = 28 patients, HC = 21 healthy controls). HAM-D score was noted to be 24.4±4.8 in the MDD group. There was no significant difference between MDD and HC groups as far as age, gender, employment status and level of education is concerned. Region-of-interest based analysis of Rs-fMRI data showed a significantly lower connectivity between the left insula and left nucleus accumbens and between left paracingulate gyrus and bilateral posterior middle temporal gyri in MDD group as compared to HC group. Discussion & Conclusions There is reduced connectivity between certain key regions of the brain in MDD patients, i.e., between the left insular cortex and left nucleus accumbens and between left paracingulate gyrus and bilateral posterior middle temporal gyrus. These findings could explain the basis of clinical features of MDD such as anhedonia, rumination of thoughts, reduced visuo-spatial comprehension, reduced language function and response to external stimuli.