Neuropsychological deficits in Huntington's disease gene carriers and correlates of early "conversion"

Abstract

The authors examined whether the baseline cognitive functioning of 21 clinically normal huntingtin mutation carriers who developed manifest Huntington's disease on follow-up differed from that of 49 mutation carriers who remain asymptomatic over the same period in a longitudinal study. One hundred thirty-four gene-negative offspring of Huntington's disease patients were studied as well. Overall, there were no differences in cognitive test performance among the three groups. However, "converters" who developed signs of Huntington's disease within 8.6 years demonstrated poorer performance on the Wisconsin Card Sorting Test at baseline. People with the Huntington's disease mutation who are carefully examined neurologically and found to be asymptomatic have, at most, very minimal problem-solving impairment, and only if they are within a few years of clinical onset.

FIGURE 1. Wisconsin Card Sorting Test Results for Huntington’s Disease Early Converters, Late Converters, and Nonconverters

Left: Inefficiency scores for patients who developed symptoms within 8.62 years (early), after 8.62 years (late), and those who remained asymptomatic. For subjects who achieved no sorts, the denominator is set at 0.5 to allow computation of this summary score. Higher scores indicate worse performance. Means+SE. Right: Number of perseverative and nonperseverative errors.