Problem solving, impulse control and planning in patients with early- and late-stage Huntington's disease.

Leonora Wilkinson,Annamaria Painold,Walter Wurm,Claudia Blesl,Anna K Holl,Adelina Tmava,Sabrina Mörkl,Nicole J Müller

doi:10.1007/s00406-016-0707-4

Abstract

Sub-domains of executive functions, including problems with planning, accuracy, impulsivity, and inhibition, are core features of Huntington’s disease. It is known that the decline of cognitive function in Huntington’s disease is related to the anatomical progression of pathology in the basal ganglia. However, it remains to be determined whether the severity of executive dysfunction depends on the stage of the disease. To examine the severity of sub-domains of executive dysfunction in early- and late-stage Huntington’s disease, we studied performance in the Tower of London task of two groups of Huntington’s disease patients (Group 1: early, n = 23, and Group 2: late stage, n = 29), as well as a third group of age, education, and IQ matched healthy controls (n = 34). During the task, we measured the total number of problems solved, total planning time, and total number of breaks taken. One aspect of executive function indexed by the number of solved problems seems to progress in the course of the disease. Late-stage Huntington’s disease patients scored significantly worse than early-stage patients and controls, and early-stage patients scored significantly worse than controls on this measure of accuracy. In contrast, late- and early-stage HD patients did not differ in terms of planning time and number of breaks. Early- and late-stage HD pathology has a different impact on executive sub-domains. While accuracy differs between early- and late-stage HD patients, other domains like planning time and number of breaks do not. Striatal degeneration, which is a characteristic feature of the disease, might not affect all aspects of executive function in HD.

Highlights

Neuropsychological deficits caused by neurodegenerative conditions, such as dementia, multiple sclerosis, amyotrophic lateral sclerosis and Huntington’s disease (HD), significantly impair patients’ abilities and affect their quality of life [1,2,3,4].HD is an autosomal-dominant trinucleotide repeat disorder with early signs of cognitive deterioration
To determine the effect of HD disease severity on accuracy during the Tower of London (ToL) task, an ANOVA was performed on mean number of solved problems with level of Difficulty as a within-subjects variable and Group as a between-group variable
For the comparison between early- and late-stage HD patients, a significant difference was found in following conditions: three-move problems [Tukey; p = .04], four-move problems [Tukey; p = .02], five-move problems [Tukey; p = .03], and six-move problems [Tukey, p < .001]

Summary

Introduction

Neuropsychological deficits caused by neurodegenerative conditions, such as dementia, multiple sclerosis, amyotrophic lateral sclerosis and Huntington’s disease (HD), significantly impair patients’ abilities and affect their quality of life [1,2,3,4].HD is an autosomal-dominant trinucleotide repeat disorder with early signs of cognitive deterioration. The first signs of cognitive dysfunction are usually the deterioration of executive functions and psychomotor speed, which are prominent signs in the preclinical stages and in early disease stages. This ‘frontal’ pattern of cognitive deterioration in HD is considered to result from early neuronal death in the caudate, which leads to dysfunction in fronto-striatal circuits [8]. Several MRI studies showed consistent degeneration of the striatum (caudate nucleus and putamen) already in presymptomatic patients [9,10,11] and in symptomatic stages of the disease [5, 12]

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