Psychophysiological indicators of dysfunctional inhibitory control in repetitive behaviors
Date
2016
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Publisher
University of Delaware
Abstract
The relationships among repetitive behaviors remain uncertain. While phenotypic distinctions have long maintained their disparate categorizations in the DSM, repetitive behaviors frequently overlap in phenomenology, neurobiology, and comorbidity. It has been suggested that dysfunctional inhibitory control may account for commonalities across these presentations. However, evidence from obsessive-compulsive disorder (OCD) and trichotillomania (TTM) suggests that, in fact, there may be heterogeneity of inhibitory control dysfunction across repetitive behaviors. In concert with NIMH’s Research Domain Criteria (RDoC) initiative to better capture associated mechanisms of dysfunction, the present study aimed to determine if the patterns of inhibitory control dysfunction found in OCD and TTM extend to other repetitive behaviors. The study integrated event-related potential (ERP) methodology with observable symptoms to examine inhibitory control in neurodevelopmental disorders characterized by repetitive behaviors (RBs; i.e., tic disorders and autism spectrum disorders). Seventy-six children (43 with RBs; 33 typically developing controls) were asked to complete two tasks targeting inhibitory control processes in two contexts: the Ericksen Flanker Task (EFT), which measured interference control, and the Stop-Signal Task, which tapped motor inhibition. In these contexts, ERPs captured two stages of inhibitory control: conflict monitoring (error-related negativity [ERN], “no-go” N2) and conflict resolution (error positivity [Pe], “no-go” P3). Despite observing expected within-person effects across behavioral measures and other ERP components, results largely indicated that individuals with RBs demonstrated intact inhibitory control, as measured by these tasks. There was a single between-group effect in conflict resolution during interference control, such that individuals with RBs had a smaller magnitude differential between Pe and Pc, suggesting less subjective awareness of errors. However, this effect should be interpreted with caution, as it did not hold across a second analysis procedure. Collectively, results indicate that inhibitory control deficits are likely not unidimensional, but instead are specific to the stage of control and the context in which control is taxed. Moreover, the specific deficits appear to vary across repetitive behaviors. Diagnostic and treatment implications are discussed.