The present study examined the coordination of prehensile forces during pre
cision grip in subjects with Huntington's disease (HD). Fingertip forces we
re measured in 12 subjects with HD and 12 age-matched controls during the l
ifting of an instrumented object whose weight and surface texture were vari
ed. The results indicate that subjects with HD have impaired initiation and
delayed transitions between movement sequences and produce excessive and v
ariable forces. However, subjects with HD demonstrated anticipatory scaling
of force development based on the object's expected physical properties (p
lanning) and adjustment of the force to the object's actual physical proper
ties (sensorimotor integration). The observed findings generally were unrel
ated to the overall disease severity. However, the variability in forces wa
s correlated with functional capacity and motor performance suggesting that
variability is a key feature of the motor deficit. These results provide i
nsights into the impaired hand function observed in individuals with HD. (C
) 2000 Academic Press.