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- Title
EEG Resting-State Functional Connectivity Abnormalities in Patients with Obsessive-Compulsive Disorder.
- Authors
Katsushige Watanabe; Ayako Isoo; Yasushi Okamura; Hiromi Kamo; Makoto Taniguchi
- Abstract
Objectives: Obsessive-compulsive disorder (OCD) is one of the most disabling of all psychiatric illness with a lifetime prevalence of 2%-3% and an early onset in adolescence or young adulthood. Core symptoms of OCD are intrusive thoughts, feelings, or images (obsessions) and repetitive behaviors (compulsions) aimed at reducing anxiety associated with obsessions. Despite available pharmacological and psychotherapeutic treatments about 10% of OCD patients remain severely affected and are considered treatment- refractory. For some of these patients deep brain stimulation (DBS) offers an appropriate treatment method. In hopes of identifying better treatment options such as DBS, many attempts have been made to clarify pathological brain mechanisms. Alterations in brain functional cortical connectivity in resting-state networks have been detected with functional imaging techniques, but neurophysiological connectivity measures have not been systematically examined. To address this question, we applied resting-state electroencephalography (EEG) to investigate the whole brain fundamental functional alterations in patients with OCD. In this study, we focused on oscillation-based functional connectivity. Methods: We used the combined application of the independent component analysis (ICA) and the Granger causality (GC) analysis to examine resting state functional connectivity as measured by routine scalp-EEG in 10 patients with OCD and 10 healthy controls matched for age lying with eyes closed in a dark sound-attenuated room. After the power spectra was computed, GC spectra method, a part of spectral interdependency methods, was used to examine the strengths, directions, and frequencies of interactions between dynamic processes. The measures of spectral interdependency were derived from the time series recordings of dynamic systems by using autoregressive modeling. The direction of information flow between these EEG sources was then estimated using the directed transfer function (DTF). Results: As compared to controls, the patients with OCD had decreased functional connectivity between medial prefrontal and occipital cortex, and between the left temporal and occipital cortex. The patients with OCD expressed lower information flow (DTF) in beta frequency range principally from the occipital to the medial prefrontal region, and from the occipital to the left temporal region. Conclusions: We used resting-state EEG to study wholebrain functional connectivity patterns in patients with OCD and healthy controls. The primary finding was changed functional connectivity in large-scale networks including the medial prefrontal cortex, temporal cortex and occipital cortex in the patients with OCD. These results indicated EEG connectivity-based measurements could probably serve as reliable and valid biomarkers for diagnosis of OCD. It has been suggested that deficits in the ability to selectively attend to relevant information while concurrently suppressing competing irrelevant information is a central feature of OCD. The impairment of inhibitory control in OCD patients might be reflected in abnormal cognitive functions, which seem to be due to reduced attention. We speculate that decrease in functional connectivity in largescale networks among the medial prefrontal cortex, temporal cortex and occipital cortex may be related to functional deficits in cognitive domains in OCD. The impact of neurological and psychiatric diseases on the functional organization of the brain has been a topic of growing interest in the last decade. It is likely that most psychiatric disorders do not result from a deficit in a single brain area and that a network perspective is necessary to explain their complex etiology. OCD is associated with abnormal intrinsic functional connectivity in large-scale brain networks. This network approach can shed some light on the pathophysiological mechanisms underlying neuropsychiatric disorders.
- Publication
Stereotactic & Functional Neurosurgery, 2016, Vol 94, p45
- ISSN
1011-6125
- Publication type
Article
- DOI
10.1159/000448961