Identification of Subtle Verbal Memory Deficits in Premanifest Huntington Disease Using the California Verbal Learning Test.

BACKGROUND: Verbal memory impairment in individuals with Huntington disease (HD) is well-documented; however, the nature and extent of verbal memory impairment in individuals with premanifest HD (pre-HD) are less understood. OBJECTIVE: To evaluate verbal memory function in individuals with pre-HD by comparing their performance on the California Verbal Learning Test to that of individuals with a clinical diagnosis of HD and that of a demographically similar group of adults with no family history of, or genetic risk for, HD, thereby reducing possible complications of psychiatric difficulties commonly experienced by individuals who are at risk for HD but are gene negative. METHODS: Participant groups included 77 adults with a diagnosis of HD, 23 premanifest gene carriers for HD (pre-HD), and 54 demographically similar, healthy adults. The California Verbal Learning Test-Second Edition (CVLT-II) was used to evaluate the participants' immediate and delayed recall, recognition, learning characteristics, errors, and memory retention. RESULTS: The pre-HD group performed significantly worse than the healthy group, yet significantly better than the HD group, on Short and Long Delay Recall (Free and Cued) and Recognition Discriminability. On Total Immediate Recall, Learning Slope, Semantic Clustering, and Intrusions, the pre-HD group performed similarly to the healthy group and significantly better than the HD group. None of the groups differed in their performance on Repetitions and a measure of retention. CONCLUSIONS: Subtle memory deficits can be observed during the premanifest stage of HD with use of a subset of indices from the CVLT-II.

Central Cognitive Processing Speed Is an Early Marker of Huntington's Disease Onset.

BACKGROUND: Several studies have suggested that cognitive processing speed may be useful for assessing early cognitive change in premanifest Huntington's disease (HD); however, current measures lack the ability to control for the effects of motor dysfunction commonly found in HD. The Computerized Test of Information Processing (CTiP) is a rapidly administered computerized tool that allows for the examination of central cognitive processing speed by using motor-corrected scores to account for motor dysfunction. OBJECTIVE: To examine central cognitive processing speed as an early marker of HD onset using the CTiP. METHODS: The CTiP and other measures were administered to 102 HD gene carriers and 55 healthy adults (HA). Gene carriers included presymptomatic HD (pre-HD; n = 33), prodromal HD (pro-HD; ie, individuals close to disease onset; n = 23), and mild-moderate HD (HD; n = 46). RESULTS: The HD group performed significantly slower than all other groups (HA, pre-HD, and pro-HD) on most subtests (Ps < .05). Moreover, the pro-HD group performed significantly slower than the HA group on both motor-corrected subtests (Ps < 0.05). Effect sizes associated with significant group differences between the pro-HD and HA groups on motor-corrected CTiP subtests (d = 0.73 and 0.84) were similar to effect sizes associated with group differences on the Symbol Digit Modalities Test (d = .82) and other traditional cognitive assessments (Montreal Cognitive Assessment, d = .75; Mini-Mental State Examination, d = .84). CONCLUSIONS: The CTiP may be a useful marker of deficits in central cognitive processing speed in individuals close to manifest onset of HD.