A - 118 Tablet-Based Cognitive Assessment Demonstrates Valid Assessment of Prodromal Huntington’s Disease

Abstract Objectives We analyzed performances on novel iPad-based assessments between at-risk gene-negative controls and participants carrying the gene causing Huntington’s Disease. TabCAT (UCSF) is used to detect mild cognitive impairment and dementia. We evaluated sensitivity in ten TabCAT assessments targeting memory, executive function, motor, and visuospatial abilities in 137 participants. We evaluated TabCAT’s effectiveness in detecting impairment in participants and assessed reliability of one test (Tempo) compared to a standard instrument (Paced Tapping). Methods Cytosine-adenine-guanine trinucleotide repeat length gene multiplied by age (CAG by age product (CAP) score) measured disease progression, based on estimated probability of manifesting motor symptoms (31 low, 41 moderate, 36 high). Controls were genetic relatives who tested negative. All statistical tests used an alpha level of 0.05. Results Significant differences were found for Favorites Learning, Favorites Delay, Flanker, and Match. Variables showed similar worsening trends from low to high; however, only differences with the high group were significant. The standardized Cronbach Coefficient Alphas were 0.68 for the first group of Paced Tapping variables, 0.91 for the second group, and 0.98 for Tempo. The standardized Cronbach Coefficient Alpha for variables of both tests was 0.82. Conclusions Grouping prodromal HD participants by disease risk compared to gene-negative controls enables cross-sectional analysis. High-risk participants performed significantly worse on tasks evaluating visual memory and executive functioning. Findings replicate previous publications showing that cognitive impairment worsens as one’s risk for motor symptom onset increases. Findings also suggest that the tablet-based assessment procedures reflect a valid representation of the insidious cognitive decline seen in traditional paper-and-pencil neuropsychological assessment.