P300 Source Localization Contrasts in Body-Focused Repetitive Behaviors and Tic Disorders.

Geneviève Sauvé,Pierre Blanchet,Kieron O’Connor,Marc Lavoie,Simon Morand-Beaulieu

doi:10.3390/brainsci7070076

Abstract

Tic disorders (TD) and body-focused repetitive behaviors (BFRB) have similar phenotypes that can be challenging to distinguish in clinical settings. Both disorders show high rates of comorbid psychiatric conditions, dysfunctional basal ganglia activity, atypical cortical functioning in the prefrontal and motor cortical regions, and cognitive deficits. Clinicians frequently confound the two disorders and it is important to find reliable objective methods to discriminate TD and BFRB. Neuropsychological tests and event-related potential (ERP) studies have yielded inconsistent results regarding a possible context updating deficit in TD and BFRB patients. However, most previous studies did not control for the presence of comorbid psychiatric condition and medication status, which might have confounded the findings reported to date. Hence, we aimed to investigate the psychophysiology of working memory using ERP in carefully screened TD and BFRB patients excluding those with psychiatric comorbidity and those taking psychoactive medication. The current study compared 12 TD patients, 12 BRFB patients, and 15 healthy control participants using a motor oddball task (button press). The P300 component was analyzed as an index of working memory functioning. Results showed that BFRB patients had decreased P300 oddball effect amplitudes over the right hemisphere compared to the TD and control groups. Clinical groups presented different scalp distributions compared to controls, which could represent a potential endophenotype candidate of BFRB and TD.

Highlights

Tic disorders (TD) and body-focused repetitive behaviors (BFRB) are two motor-related neuropsychiatric afflictions that can be difficult to distinguish in clinical settings because they often co-occur and because their symptoms can be confounded [1,2]
event-related potential (ERP) analysis revealed that patients with TD showed no significant P300 effect, while the BFRB group presented a significant P300 amplitude reduction, shifted over the right temporal region, in comparison to both TD and control groups. Standardized low-resolution brain electromagnetic tomography (sLORETA) analysis further confirmed that the two clinical groups exhibited different scalp distributions of the oddball effect, compared to the control group
Our study showed decreased P300 amplitudes and different distribution of cortical activity in unmedicated patients solely affected by BFRB

Summary

Introduction

Tic disorders (TD) and body-focused repetitive behaviors (BFRB) are two motor-related neuropsychiatric afflictions that can be difficult to distinguish in clinical settings because they often co-occur and because their symptoms can be confounded [1,2]. Brain Sci. 2017, 7, 76; doi:10.3390/brainsci7070076 www.mdpi.com/journal/brainsci. Brain Sci. 2017, 7, 76 of TD patients present comorbid disorders such as BFRB, and depression, anxiety, and obsessive-compulsive disorder (OCD) [3,4,5]. Tics are repetitive and sudden movements or vocalizations that can range from simple actions (e.g., eye blinks) to complex sequences of movements (e.g., head and finger contortions) [7]. BFRB is an umbrella term for debilitating, repetitive habits and behaviors that target one or more body regions

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