Introduction: This study evaluates the impact of Parkinson disease (PD) medication in advanced PD on neuropsychological performance, psychiatric symptoms, impulsivity and the quality of life. In the 4-year period 27 patients with advanced PD, scheduled for deep brain stimulation (DBS) surgery (N=27, mean age: 58.9±7.1, disease duration: 10.0 years±4.2) were examined preoperatively. We hypothesized that a high dosage of PD medication or current use of dopamine agonists affect cognitive functioning and psychiatric wellbeing.
Methods: We performed two subgroup analyses with low versus high levodopa-equivalent Dosage (LED) medication and without versus with dopaminagonistic medication.
Results: The neuropsychological testing revealed significant differences in the verbal learn- and memory-test (VLMT) during the learning passage (U=36.500, Z=- 2.475, p=0.012) and in the subtest of the semantic fluency of Regensburg verbal fluency test (RWT) (t(25)=- 2.066, p=0.049) with better results for patients without dopaminagonistic medication. Pearson correlation analyses of LED in correlation with the clinical and cognitive dependent variables showed a significant higher PANSS total score in patients with higher LED medication (r=0.491, p=0.009). In addition, lower LED treatment was associated with significant higher scores in the impulsivity perseverance subtest (r=- 0.509, p=0.008).
Discussion: In conclusion, we found lower LEDs to be correlated with a better perseverance in the impulsivity test and additional treatment with a dopamine agonist influenced some verbal learning tasks and the PANSS total score in patients with advanced PD. This should be considered prior to DBS surgery.
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