Functional connectivity abnormalities of brain networks in obsessive–compulsive disorder: a systematic review

Abstract

Obsessive-compulsive disorder (OCD) is characterized by cognitive abnormalities encompassing several executive processes. Neuroimaging studies highlight functional abnormalities of executive fronto-parietal network (FPN) and default-mode network (DMN) in OCD patients, as well as of the prefrontal cortex (PFC) more specifically. We aim at assessing the presence of functional connectivity (FC) abnormalities of intrinsic brain networks and PFC in OCD, possibly underlying specific computational impairments and clinical manifestations. A systematic review of resting-state fMRI studies investigating FC was conducted in unmedicated OCD patients by querying three scientific databases (PubMed, Scopus, PsycInfo) up to July 2022 (search terms: “obsessive–compulsive disorder” AND “resting state” AND “fMRI” AND “function* *connect*” AND “task-positive” OR “executive” OR “central executive” OR “executive control” OR “executive-control” OR “cognitive control” OR “attenti*” OR “dorsal attention” OR “ventral attention” OR “frontoparietal” OR “fronto-parietal” OR “default mode” AND “network*” OR “system*”). Collectively, 20 studies were included. A predominantly reduced FC of DMN – often related to increased symptom severity – emerged. Additionally, intra-network FC of FPN was predominantly increased and often positively related to clinical scores. Concerning PFC, a predominant hyper-connectivity of right-sided prefrontal links emerged. Finally, FC of lateral prefrontal areas correlated with specific symptom dimensions. Several sources of heterogeneity in methodology might have affected results in unpredictable ways and were discussed. Such findings might represent endophenotypes of OCD manifestations, possibly reflecting computational impairments and difficulties in engaging in self-referential processes or in disengaging from cognitive control and monitoring processes.

Brain alterations in individuals with exercise dependence: A multimodal neuroimaging investigation

“…Based on this evidence, our finding of increased right IFG-SPL coupling in individuals with ED may reflect the generation of motor representations, as well as the preparation of subsequent motor actions and their monitoring ( Loffler, Haggard, & Bode, 2020 ; Si, Rowe, & Zhang, 2021 ). Notably, increased fronto-parietal resting-state connectivity has repeatedly been observed in obsessive-compulsive disorder ( Fornaro & Vallesi, 2023 ). IFG-SPL hyperconnectivity may thus underlie a lack of cognitive control over compulsive behaviours, in this case, exercise.…”

The Effect of Symptom-Provocation on Inhibitory Control in Obsessive-Compulsive Disorder Patients Is Contingent upon Chronotype and Time of Day

“…It is also possible that symptom-provoking stimuli induce obsessions that overload OCD patients’ inhibition and limit patients’ ability to inhibit their responses [ 13 , 62 ]. On a neurobiological level, patients’ reduced ability to inhibit responses to symptom-provoking stimuli in external tasks (like the stop signal task) may reflect interference in downregulating their default mode network—a large-scale brain network associated with self-referential processes [ 63 , 64 , 65 ]. Taken together, the above studies combined with the findings of the current study provide support for the notion that symptom-provocation is associated with impaired inhibition in individuals with OCD, a mechanism which may underlie the vicious cycle of obsessions/anxiety and compulsions in OCD.…”