Background: Dopaminergic drugs, the gold standard for motor symptoms, are known to affect cognitive function in Parkinson's disease (PD) patients.
Objective: We compared the effects of dopaminergic treatment on motor and cognitive function in drug-naïve patients.
Methods: Dopaminergic medication (levodopa, dopamine agonist, selegiline) was given to 27 drug-naïve PD patients and increased to a dose optimal for improved motor symptoms. Patients were tested prior to, and 4-7 months after, drug initiation. Motor function was assessed using the Unified Parkinson's Disease Rating Scale (UPDRS). Cognitive function was assessed using both the Japanese version of the Montreal Cognitive Assessment (MoCA-J) and the Neurobehavioral Cognitive Status Examination (COGNISTAT-J). Improvements from baseline for both motor and cognitive assessment were compared.
Results: Mean score of all motor assessments (UPDRS total score of Parts II and III, and sub-scores of tremor, rigidity, bradykinesia, gait, and postural instability) and certain cognitive assessments (MoCA-J total score and subscore of delayed recall) significantly improved with dopaminergic medication. Gait score improvement showed significant positive correlation with improvement in MoCA-J language domain and in language-comprehension subtests of COGNISTAT-J using Spearman's correlation coefficients. Furthermore, multiple regression analysis showed gait score improvement significantly correlated with improvements in the subtests of language-comprehension in COGNISTAT-J.
Conclusion: There is correlated improvement in both gait and language function in de novo PD patients in response to dopaminergic drugs. Gait and language dysfunction in these patients may share a common pathophysiology linked to dopamine deficits.
Keywords: Parkinson’s disease; cognition; executive function; gait; language; verbal fluency disorders; working memory.