Arithmetic Word-Problem Solving as Cognitive Marker of Progression in Pre-Manifest and Manifest Huntington's Disease.

BACKGROUND Arithmetic word-problem solving depends on the interaction of several cognitive processes that may be affected early in the disease in gene-mutation carriers for Huntington's disease (HD). OBJECTIVE Our goal was to examine the pattern of performance of arithmetic tasks in premanifest and manifest HD, and to examine correlations between arithmetic task performance and other neuropsychological tasks. METHODS We collected data from a multicenter cohort of 165 HD gene-mutation carriers. The sample consisted of 31 premanifest participants: 16 far-from (>12 years estimated time to diagnosis; preHD-A) and 15 close-to (≤12 years estimated time to diagnosis; preHD-B), 134 symptomatic patients (early-mild HD), and 37 healthy controls (HC). We compared performance between groups and explored the associations between arithmetic word-problem solving and neuropsychological and clinical variables. RESULTS Total arithmetic word-problem solving scores were lower in preHD-B patients than in preHD-A (p <  0.05) patients and HC (p <  0.01). Early-mild HD patients had lower scores than preHD patients (p <  0.001) and HC (p <  0.001). Compared to HC, preHD and early-mild HD participants made more errors as trial complexity increased. Moreover, arithmetic word-problem solving scores were significantly associated with measures of global cognition (p <  0.001), frontal-executive functions (p <  0.001), attention (p <  0.001) and visual working memory (p <  0.001), mental rotation (p <  0.001), and confrontation naming (p <  0.05). CONCLUSION Arithmetic word-problem solving is affected early in the course of HD and is related to deficient processes in frontal-executive and mentalizing-related processes.