Mild cognitive impairment in prediagnosed Huntington disease.

BACKGROUND: Cognitive decline has been reported in Huntington disease (HD), as well as in the period before diagnosis of motor symptoms (i.e., pre-HD). However, the severity, frequency, and characterization of cognitive difficulties have not been well-described. Applying similar cutoffs to those used in mild cognitive impairment (MCI) research, the current study examined the rates of subtle cognitive dysfunction (e.g., dysfunction that does not meet criteria for dementia) in pre-HD. METHODS: Using baseline data from 160 non-gene-expanded comparison participants, normative data were established for cognitive tests of episodic memory, processing speed, executive functioning, and visuospatial perception. Cutoff scores at 1.5 standard deviations below the mean of the comparison group were then applied to 575 gene-expanded pre-HD participants from the observational study, PREDICT-HD, who were stratified by motor signs and genetic risk for HD. RESULTS: Nearly 40% of pre-HD individuals met criteria for MCI, and individuals closer to HD diagnosis had higher rates of MCI. Nonamnestic MCI was more common than amnestic MCI. Single-domain MCI was more common than multiple-domain MCI. Within the nonamnestic single-domain subtype, impairments in processing speed were most frequent. CONCLUSIONS: Consistent with the Alzheimer disease literature, MCI as a prodromal period is a valid concept in pre-HD, with nearly 40% of individuals showing this level of impairment before diagnosis. Future studies should examine the utility of MCI as a marker of cognitive decline in pre-HD.

Detection of Huntington's disease decades before diagnosis: the Predict-HD study.

OBJECTIVE: The objective of the Predict-HD study is to use genetic, neurobiological and refined clinical markers to understand the early progression of Huntington's disease (HD), prior to the point of traditional diagnosis, in persons with a known gene mutation. Here we estimate the approximate onset and initial course of various measurable aspects of HD relative to the time of eventual diagnosis. METHODS: We studied 438 participants who were positive for the HD gene mutation, but did not yet meet the diagnostic criteria for HD and had no functional decline. Predictability of baseline cognitive, motor, psychiatric and imaging measures was modelled non-linearly using estimated time until diagnosis (based on CAG repeat length and current age) as the predictor. RESULTS: Estimated time to diagnosis was related to most clinical and neuroimaging markers. The patterns of association suggested the commencement of detectable changes one to two decades prior to the predicted time of clinical diagnosis. The patterns were highly robust and consistent, despite the varied types of markers and diverse measurement methodologies. CONCLUSIONS: These findings from the Predict-HD study suggest the approximate time scale of measurable disease development, and suggest candidate disease markers for use in preventive HD trials.

A review of subtyping in autism and proposed dimensional classification model.

Autism has been divided into subtypes based on social interaction/communication, developmental level, or both. The validity of subtyping systems and the extent to which they overlap were examined. According to this review, a single subtyping system capable of accounting for the symptom heterogeneity in autism has not yet been proposed; however, evidence supports the presence of a three-factor continuum containing at least four subgroups. Foremost among directions for future research is the need for comprehensive studies in which medical screening, careful selection of measures, and longitudinal data collection are included.

Young and elderly adults' perceptions of the Wechsler Adult Intelligence Scale-Revised.

Because little information exists on examinees' perceptions of the Wechsler Adult Intelligence Scale-Revised (WAIS-R), this study was designed to assess such perceptions in two groups: young adults (n = 50, age 18-25 years) and elderly adults (n = 46, age 65-96 years). Each participant completed the WAIS-R followed by an opinion questionnaire. Both groups gave positive ratings overall. However, elderly participants rated the WAIS-R more positively than young participants both globally and on six of the eleven subtests. These findings suggest that the WAIS-R is viewed favorably by most examinees, particularly elderly adults. Implications for practitioners are presented.