Disentangling the neurobiological bases of temporal impulsivity in Huntington's disease

Abstract

BackgroundDespite its impact on daily life, impulsivity in Huntingtons disease (HD) is understudied as a neuropsychiatric symptom. Our aim is to characterize temporal impulsivity in HD, evaluated through a Delay Discounting (DD) task, and to disentangle the underlying white matter correlates in HD. MethodsForty-seven HD individuals and thirty-six healthy controls conducted a DD task and complementary Sensitivity to Punishment and Sensitivity to Reward (SR) Questionnaire. Diffusion-tensor imaging was employed to characterize the structural connectivity of two limbic tracts: the uncinate fasciculus (UF) and the accumbofrontal tract (NAcc-OFC). Multiple linear regression analyses were applied to analyze the relationship between impulsive behavior and white-matter microstructural integrity. ResultsAltered structural connectivity in both the NAcc-OFC and UF in HD individuals was observed. Moreover, the variability in structural connectivity of these tracts was associated with the individual differences in temporal impulsivity. Specifically, increased structural connectivity in the right NAcc-OFC predicted increased temporal impulsivity, while reduced connectivity in the left UF was associated with higher temporal impulsivity scores. LimitationsOther cognitive mechanisms and white matter tracts may play a role in temporal impulsivity. ConclusionsThis study provides evidence that individual differences observed in impulsivity may be explained by variability in limbic fronto-striatal tracts. We emphasize the importance of investigating the spectrum of impulsivity in HD, less prevalent than other psychiatric features, but impacting the quality of life of patients and their caregivers.