title: Reduced functional connectivity within the limbic cortico-striato-thalamo-cortical loop in unmedicated adults with obsessive-compulsive disorder.
abstract: Cortico-striato-thalamo-cortical (CSTC) loops project from the cortex to the striatum, then from the striatum to the thalamus via the globus pallidus, and finally from the thalamus back to the cortex again. These loops have been implicated in Obsessive-Compulsive Disorder (OCD) with particular focus on the limbic CSTC loop, which encompasses the orbitofrontal and anterior cingulate cortices, as well as the ventral striatum. Resting state functional-connectivity MRI (rs-fcMRI) studies, which examine temporal correlations in neural activity across brain regions at rest, have examined CSTC loop connectivity in patients with OCD and suggest hyperconnectivity within these loops in medicated adults with OCD. We used rs-fcMRI to examine functional connectivity within CSTC loops in unmedicated adults with OCD (n = 23) versus healthy controls (HCs) (n = 20). Contrary to prior rs-fcMRI studies in OCD patients on medications that report hyperconnectivity in the limbic CSTC loop, we found that compared with HCs, unmedicated OCD participants had reduced connectivity within the limbic CSTC loop. Exploratory analyses revealed that reduced connectivity within the limbic CSTC loop correlated with OCD symptom severity in the OCD group. Our finding of limbic loop hypoconnectivity in unmedicted OCD patients highlights the potential confounding effects of antidepressants on connectivity measures and the value of future examinations of the effects of pharmacological and/or behavioral treatments on limbic CSTC loop connectivity.
authors.affiliation: Department of Psychiatry, Division of Child and Adolescent Psychiatry, Columbia College of Physicians and Surgeons, New York, New York; Institute for Molecular Medicine, School of Medicine, University of Lisbon, and Department of Psychiatry, Columbia University, New York State Psychiatric Institute, New York, New York.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Posner
authors.forename: Rachel
authors.initials: R
authors.lastname: Marsh
authors.forename: Tiago V
authors.initials: TV
authors.lastname: Maia
authors.forename: Bradley S
authors.initials: BS
authors.lastname: Peterson
authors.forename: Allison
authors.initials: A
authors.lastname: Gruber
authors.forename: H Blair
authors.initials: HB
authors.lastname: Simpson
mesh_terms: D000328:Adult; D001921:Brain / Q000503:physiopathology*; D001931:Brain Mapping; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009434:Neural Pathways / Q000503:physiopathology; D009771:Obsessive-Compulsive Disorder / Q000503:physiopathology*; D011569:Psychiatric Status Rating Scales; D012146:Rest / Q000502:physiology; D055815:Young Adult
keywords: functional connectivity; obsessive-compulsive disorder; orbitofrontal cortex; striatum