Intra-individual Variability in Prodromal Huntington Disease and Its Relationship to Genetic Burden. (26th January 2015)

• Record Type: Journal Article
• Authors: Musso, Mandi; Westervelt, Holly James; Long, Jeffrey D.; Morgan, Erin; Woods, Steven Paul; Smith, Megan M.; Lu, Wenjing; Paulsen, Jane S.
• Is Part Of: Journal of the International Neuropsychological Society. Volume 21:Number 1(2015:Jan.)
• Page Start: 8
• Page End: 21
• Publication Date: 2015-01-26
• Subjects: Huntington disease, -- Neuropsychological tests, -- Executive function, -- Attention, -- Adult, -- Cognition disorders/diagnosis, -- Cognition disorders/genetics, -- Prodromal symptoms, -- Intra-individual variability; Neuropsychology -- Periodicals; 616.8
• DOI: 10.1017/S1355617714001076
• Languages: English
• ISSNs: 1355-6177

Abstract

Abstract: The current study sought to examine the utility of intra-individual variability (IIV) in distinguishing participants with prodromal Huntington disease (HD) from nongene-expanded controls. IIV across 15 neuropsychological tasks and within-task IIV using a self-paced timing task were compared as a single measure of processing speed (Symbol Digit Modalities Test [SDMT]) in 693 gene-expanded and 191 nongene-expanded participants from the PREDICT-HD study. After adjusting for depressive symptoms and motor functioning, individuals estimated to be closest to HD diagnosis displayed higher levels of across- and within-task variability when compared to controls and those prodromal HD participants far from disease onset ( F ICV (3, 877) =11.25; p <.0001; F PacedTiming (3, 877) =22.89; p <.0001). When prodromal HD participants closest to HD diagnosis were compared to controls, Cohen's d effect sizes were larger in magnitude for the within-task variability measure, paced timing (−1.01), and the SDMT (−0.79) and paced tapping coefficient of variation (CV) (−0.79) compared to the measures of across-task variability [CV (0.55); intra-individual standard deviation (0.26)]. Across-task variability may be a sensitive marker of cognitive decline in individuals with prodromal HD approaching disease onset. However, individual neuropsychological tasks, including a measure of within-task variability, produced larger effect sizes than an index of across-task IIV in this sample. ( JINS, 2015, 21, 8–21)