Cognitive-motor dysfunction in Parkinson's disease.

Patients with Parkinson's disease (PD) present with a wide range of cognitive and motor dysfunctions. Attempts to fit these deficits into a neuroanatomical framework have tended to emphasise their separateness. This paper, however, takes a broader perspective based on the concept of action-purposeful goal-directed behaviour-which serves to integrate the various deficits into a common framework. Of the motor symptoms of PD, akinesia is chosen as representing a breakdown in a distributed system of action control. Three aspects of akinesia are considered-slowness to initiate movement, slowness to execute movement and poverty of spontaneous movement. All are seen as being surface manifestation of the system's attempts to cope with or adapt to the limitations imposed by the disease process, at a cognitive, motor and integrative level.