Reaction time variability and attentional impairment in hoarding disorder

Attention appears to be impaired in hoarding disorder (HD), although it remains unclear whether this can be conceptualized as co-occurring ADHD or intrinsic to hoarding pathology. Self-reported cognitive impairment tends to be inconsistent in HD, with individuals tending to overestimate cognitive impairment compared with performance on neuropsychological tests. A behavioral index of attentional impairment during decision making, ex-Gaussian modeling of reaction times, has been commonly used as an index of inattention in ADHD, with more skew (i.e., higher tau values) suggestive of attentional lapses. We used a sample of 43 individuals with hoarding disorder who completed a decision task, comparing their ex-Gaussian reaction time curves, ex-Gaussian vectors, and similarities between them, to samples of individuals high in anxiety and depression ("anxiety and mood", n = 25) and nonclinical controls ("healthy control," HC, n = 39). Results indicated that individuals with HD exhibited tau (and sigma and mu) profiles in their scalar and vectorial metrics that were like those of the AM and HC groups, suggesting a lack of ADHD-like attentional lapses. However, the HD group showed significantly greater within-group variance than the other two diagnostic groups, suggesting substantial within-HD heterogeneity, and possibly implying inattentive and non-inattentive subtypes of HD. Hence, HD shows heterogeneous RT dynamics without generalized attentional slowing.