Longitudinal study evaluating neuropsychological changes in so-called asymptomatic carriers of the Huntington's disease mutation after 1 year.

OBJECTIVES: To determine (1) whether the battery of neuropsychological tests was sufficiently sensitive to find differences between symptomatic patients with Huntington's disease (HD) and clinically asymptomatic individuals carrying the HD gene (AGC) and individuals without the HD gene (NGC) and (2) whether increasing cognitive impairment is found in AGC as compared with NGC.
METHODS: A case-control, single-blind study comparing subjects with clinically manifest HD (n=21), AGC (n=12) or NGC (n=11) and a 1-year follow-up of AGC and NGC. Genotype for the HD gene was determined by molecular testing. A large battery of neuropsychological tests measuring several cognitive domains was performed.
RESULTS: On most neuropsychological tasks, HD patients perform significantly worse than AGC and NGC. At baseline and follow-up examination, compared with NGC, AGC had lower scores on the symbol digit modalities test. Scores on a block span task declined more rapidly among AGC than among NGC.
CONCLUSION: Cognitive impairments in HD patients are found when compared with clinically asymptomatic individuals carrying the HD mutation. Furthermore, our results suggest that subtle cognitive deficits are present in asymptomatic persons who have inherited the HD gene.