Antisaccades and executive dysfunction in early drug-naive Parkinson's disease: The discovery study.
Antoniades CA., Demeyere N., Kennard C., Humphreys GW., Hu MT.
BACKGROUND: Cognitive impairment is well recognized in Parkinson's disease (PD), but when it begins to develop is unclear. The aim of this study was to identify early signs of cognitive impairment along with abnormalities in saccadic behavior in newly diagnosed unmedicated PD patients. METHODS: Nineteen drug-naive PD patients and 20 controls were examined using a battery of tests, including an antisaccade task, phonemic and semantic verbal fluencies, and a switching and rule finding task. RESULTS: With simple tasks, no differences were found between the two groups. However, cognitive performance of the two groups diverged with more complex tasks, occurring independently of PD-related motor impairment. Patients exhibited higher antisaccadic error rates and switch costs in the task switching test, and performed significantly worse in the rule finding task. CONCLUSIONS: Certain cognitive domains and saccadic parameters are already significantly impoverished in newly diagnosed Parkinson's patients, even before the initiation of medication.