Mental and motor switching in Parkinson's disease

Switching difficulties in Parkinson's disease (PD) are expressed in both me ntal and motor tasks. The authors of the present study investigated whether those deficits coexist in the same patient and are positively correlated. They tested 8 nondemented PD patients and 6 age-matched control participant s by using the modified Wisconsin Card Sorting Test and a motor switching p aradigm that is based on the task of reaching toward visual targets, the lo cation of which could unexpectedly be altered within the reaction time. In both mental and motor tasks, patients performed significantly worse than co ntrols. There were no significant correlations between the two types of pat hology in individual patients. Mental and motor switching deteriorate in PD patients, but the deficits are not necessarily of parallel severity.