Inhibition and flexibility in Hoarding, and OCD: similarities in neuropsychological profile
Meulen, M.T. van der
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Introduction Cognitive impairment of executive functioning in patients diagnosed with Hoarding Disorder (HD) and Obsessive-Compulsive Disorder (OCD), particularly in the domains of mental flexibility and motor- and impulse control, is well established in a number of studies. However, research is inconsistent, leading to an ongoing debate on the conceptualization of Hoarding. Therefore, the aim of the present study was to examine whether ADHD and autism symptoms and related neuropsychological profile are a linking pin between Hoarding and OCD. Methods 66 Participants were recruited: 19 OCD patients, 22 Hoarders and 22 Controls. Diagnosis of Hoarding and OCD was based on the Structured Interview of Hoarding Disorder (SIHD), the Saving Inventory-Revisited (SI-R), the Obsessive-Compulsive Inventory - Revisited (OCI-R) and the Structured Clinical Interview for DSM-IV Axis-I Disorders (SCID-I). Screening for ASD and ADHD symptoms was based on the Autism-Spectrum Quotient (AQ), the Connors Adult ADHD Rating Scales (CAARS) and the Behavioral Inhibition Scale (BIS). Obsessive-Compulsive Personality Disorder (OCPD) traits were measured by the Structured Clinical Interview for DSM-IV Axis-II Disorders (SCID-II), as an indicator for mental inflexibility. Cognitive function was assessed through a comprehensive and standardized neuropsychological test battery, comprising the Intra-Dimensional Extra-Dimensional Set shift task (ID/EDS), the Stroop-Color-Word Interference task as part of the D-KEFS and the Stop Signal Reaction Time task (SSRT). The executive functions under study were mental flexibility and motor- and impulse inhibition. Results The current study showed remarkable similarities between Hoarders and OCD patients, both at the symptom level (OC symptoms, behavioral inhibition, ADHD symptoms) and at the level of executive functions (motor and cognitive inhibition). Results on cognitive flexibility and set shifting pointed into different directions, suggesting that the problems of patients slightly diverge there. However, at the level of symptoms, Hoarding, OCD, ASD and ADHD by and large overlap. Conclusion The data partially confirmed that Hoarders and OCD patients show similar impairments in mental flexibility and motor - and cognitive inhibition, deficits that are also seen in ASD and ADHD. These data do not support the conceptualization of Hoarding as a separate disorder in the DSM-V. The findings are a step in the process of identifying shared and non-shared neuropsychological mechanisms underlying Hoarding, OCD, ASD and ADHD.