Early cognitive and motor symptoms in identified carriers of the gene for Huntington disease.

OBJECTIVE: To study early motor and cognitive symptoms in Huntington disease. DESIGN: A follow-up cohort study after a DNA test procedure in which gene carriers and noncarriers were identified among people genetically at risk for Huntington disease. SETTING: Leiden University Medical Center, Department of Neurology, Leiden, the Netherlands, in cooperation with the Clinical Genetics Center Leiden and the Department of Medical Psychology and Psychotherapy, Erasmus University Rotterdam, Rotterdam, the Netherlands. PARTICIPANTS: Thirty-three individuals: 9 unaffected gene carriers, 6 gene carriers with motor symptoms, and 18 noncarriers of the gene for Huntington disease. MAIN OUTCOME MEASURES: A neuropsychologic examination covering a broad area of cognitive functioning, reaction time procedures, and motor tasks. RESULTS: The neuropsychologic assessment showed no significant differences between presymptomatic gene carriers and noncarriers. Three motor tasks differentiated between these 2 groups on a liberal .05 P level (analysis of variance followed by the Student test). The affected gene carriers performed less well than the presymptomatic gene carriers and the noncarriers in 10 motor tasks and 7 cognitive tasks. These differences were significant at P < .05. CONCLUSION: Motor symptoms play a more prominent and unequivocal role than cognitive symptoms in early stages of Huntington disease.

Intelligence indices in people with a high/low risk for developing Huntington's disease.

Intelligence in 20 presymptomatic subjects with an increased risk (> 95%) for carrying the gene for Huntington's disease (HD) was studied in a prospective, case-control, single blind study. No significant differences between the groups were detected for intelligence indices and subtest scores (Wechsler Adult Intelligence Scale). The high level of the performance IQ and the significant discrepancy between performance IQ and verbal IQ found in both the high risk and the low risk groups contrasted with our expectations based on anamnestic information, general clinical opinion, and the results of previously conducted studies. We propose that psychosocial circumstances could explain the test results and discuss the consequences of our findings for clinical genetics practice.

Memory and learning are not impaired in presymptomatic individuals with an increased risk of Huntington's disease.

Retrieval from long-term memory in patients with brain injuries was investigated with a memory scanning paradigm (Conway & Engle, 1994), that allows dissociation of scanning processes within short-term memory and memory retrieval processes from long-term memory. The study focused on the influence of brain injury on memory retrieval processes that are assumed to be automatic. Thirteen patients with memory impairment and 13 healthy matched control subjects were tested. In general, patients showed increased reaction times, but they showed set size independent retrieval from long-term memory indicating preserved automatic retrieval processes. In a subgroup of patients with more severe memory deficits, however, automatic retrieval processes appeared not to be intact. Learning profiles of the patients were characterized by smaller item chunks, indicating differences in the process of information acquisition.