Cognitive slowing in Parkinson's disease resolves after practice.
OBJECTIVE
To assess the effect of dopaminergic repletion on working memory in Parkinson's disease.


METHODS
The role of dopaminergic state on working memory in patients with Parkinson's disease was determined using the Sternberg item recognition paradigm, a continuous performance task that dissociates the motor and cognitive components of response time. Ten patients with Parkinson's disease were tested in an "on" state (on dopaminergic drug treatment) and a practical "off" state in two sessions held one week apart in counterbalanced order; 10 controls matched for age and education were studied at the same time points.


RESULTS
Patients with Parkinson's disease showed impaired working memory, independent of motor slowing. During session 1, the performance of the patients was worse than the controls, regardless of dopaminergic state. The patients showed a significant improvement in the cognitive component of task performance during the second session, such that they no longer differed from the controls. The performance of the control subjects remained stable over the two sessions.


CONCLUSIONS
Working memory performance of patients with Parkinson's disease did not change in association with dopaminergic state; rather, the performance improved over time. The pattern of improvement over time suggests a delay in proceduralising the task, similar to the deficits shown by such patients in procedural learning of other tasks.
Press
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DZ
Behavioral Neurology Unit and Movement Disorders Center, Department of Neurology, Beth Israel Deaconess Medical Center, Boston, Massachusetts 02215, USA. dpress@caregroup.harvard.edu
Mechanic
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Tarsy
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Manoach
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D000368:Aged; D000978:Antiparkinson Agents / Q000627:therapeutic use; D003072:Cognition Disorders / Q000175:diagnosis / Q000209:etiology*; D006801:Humans; D007980:Levodopa / Q000627:therapeutic use; D008875:Middle Aged; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000150:complications* / Q000188:drug therapy; D011597:Psychomotor Performance; D011897:Random Allocation; D011930:Reaction Time; D012720:Severity of Illness Index
D000978:Antiparkinson Agents; D007980:Levodopa