Parametric control of fingertip forces during precision grip lifts in children with DCD (developmental coordination disorder) and DAMP (deficits in attention motor control and perception)

Twenty boys with developmental coordination disorder (DCD), 11 of whom had associated attention deficit disorder (ADD), were compared with an age-matc hed control group of 12 boys to examine mechanisms that adapt the grip forc e at the digit-object interface in a precision grip task. An experimental g rip object equipped with pressure transducers registered the grip forces (n ormal to the surface) and the load force (tangential to the surface) genera ted by the fingertips. The surface of the object was changed to vary the fr ictional properties. Both study groups exhibited disturbances of the basic coordination of forces in the initial phase of the movement, manifested by longer time latencies and higher force levels than the control group. All s ubjects were able to adapt the force output in response to the friction at the digit-object interface. Higher grip forces and safety margins were docu mented for the DCD group in comparison to the controls. Furthermore, there was greater variation in the parametric control of the grip force in the DC D group. The results suggest that the control of the grip force is similar in children with DCD, regardless of whether they have associated ADD or not , but it is impaired in comparison to that of controls. (C) 2001 Elsevier S cience Ltd. All rights reserved.