Comparative analysis of cognitive profiles of Huntington’s and Parkinson’s diseases

Abstract

Objective: In this study, our aim is to define the cognitive profile specific to Huntington’s disease (HD) in comparison to Parkinson’s disease (PD) without any accompanying cognitive involvement and to search for its relationship with CAG repeat number. Materials and Methods: Demographic data and detailed cognitive test results of HD and PD patients were reviewed, analyzed retrospectively and were compared to results of healthy controls (HC). Cognitive test battery included minimental state examination (MMSE), Beck’s depression inventory, enhanced cued recall (ECR), semantic fluency, digit-span forwards and backwards, trail making part A (TMT A) and B, reciting months backwards, phonemic fluency, Stroop, clock drawing, Benton’s line orientation, Benton’s facial recognition and Hooper visual organization tests. Instrumental activities of daily living test (IADL) was given for evaluating independence of patients in daily life. The relationship between test results and CAG repeat number and CAP score (product of CAG repeat number and age) for HD were evaluated. Results: Age, disease duration and number of years of education were similar between HD and PD. All cognitive test results of HD group were significantly worse than those of HC. HD group also scored significantly worse than PD group in MMSE, ECR, semantic fluency, TMT A, reciting months backwards, phonemic fluency, Stroop 1-5, clock drawing, Hooper visual organization and Benton’s facial recognition tests. CAP score was significantly correlated with the results of Stroop part 3-4 and scores of IADL. Conclusion: This study showed that HD has a cognitive profile with certain particular features, which differentiates it from PD. We can also conclude that cognitive decline takes place earlier in the course of HD compared to PD and it is more severe. CAP score was found corelated with executive functions and ADL in HD, confirming that the severity of pathological involvement is directly related to the cognitive profile of patients as well as their life quality.