Assessment of complex movements reflects dysfunction in Huntington's disease

Results of various complex instrumental tools, rating scales, caudate atrophy and CAG repeat length may reflect the severity of Huntington's disease (HD). A simple assessment task for dysfunction due to disease is the standardized, computer based performance of peg insertion. The objectives of our study were to compare scored HD symptoms, computed bicaudate diameter ratio (BDR), age related genetic disease load (CAG index = [CAG-35.5 x age]) and peg insertion scores between asymptomatic 34 HD gene carriers, 89 previously untreated HD patients with psychiatric or motor symptoms, or both, and 51 treated HD patients. We measured the period of the total time taken to insert 25 pegs from a rack into a series of appropriate holes, calculated the CAG index, estimated the bicaudate diameter ratio (BDR) of a current brain CT and scored the HD patients under blind conditions. Times for the peg insertion task significantly differed between HD patients and controls, but not between HD gene carriers and controls. BDR and CAG index reflected the increase of symptoms in HD. Peg insertion results and scored severity of HD, BDR and CAG index significantly correlated with each other. Peg insertion scores are not specific diagnostic markers for HD, but they reflect clinical symptoms of neurodegeneration. The performance of peg insertion involves visuospatial cognition, self-elaboration of internal strategies, sorting and planning of movement. Therefore peg insertion particularly reflects executive dysfunction in early HD and additionally motor impairment in advanced HD.