The study of levodopa-induced dyskinesia (LID) seems to correlate with cognitive decline, as well as with the development of Parkinson's dementia (PD), the researchers found. The results of this study have been published in Neurology.
A total of 119 patients with PD who were treated with levodopa for more than 5 years were included in this retrospective cohort study. All patients underwent neuropsychological and cerebral MRI at baseline and follow-up N– (3-[[[[18F]fluoropropyl) -2β-carbomethoxy-3β- (4-iodophenyl) nortropane (18F-FP-CIT) positron emission tomography examinations. Patients were classified as LID (PD-LID +; n = 38) or not with LID (PD-LID-; n = 81). In an analysis adjusted for age, sex, years of education, body mass index, baseline motor severity and levodopa increase at year, researchers compared rates of cognitive decline using a mixed linear model and dementia conversion between PD-LID + and PD -LID- groups.
There was no difference between the 2 groups at baseline with regard to neuropsychological performance or the percentage of patients with mild cognitive impairment. Patients in the PD-LID + group presented significantly faster frontal executive function decreases than in the PD-LID- group (-0.149; P = .002). Furthermore, the PD-LID + group had significantly faster decrements in global cognitive function (-0.090; P = .033) and Mini-Mental State Examination total score (-0.351; P = .012).
Furthermore, patients in the PD-LID + group had a higher conversion rate to dementia than those in the PD-LID group (adjusted risk ratio [aHR], 3.94; 95% CI, 1.76-8.82; P = .010). The PD-LID + group also demonstrated a risk of conversion of higher PD dementia if it had mild cognitive impairment compared to those in the PD-LID group with normal cognition (aHR, 6.08, 95% CI, 1.25-29.56) mild cognitive impairment (aHR 4.05; 95% CI, 1.14-14.43).
The limits of the study include the high exclusion rate and the retrospective nature of the analysis.
The results of this study "give us a new perspective in the study of the pathophysiology of LID and cognitive decline in PD and the contributions of chronic dopaminergic stimulation to plasticity to cognition", the researchers concluded.
Yoo HS, Chung SJ, Lee YH, et al. Levodopa-induced dyskinesia is closely linked to the progression of frontal dysfunction in PD [published online February 22, 2019]. Neurology. doi: 10.1212 / WNL.0000000000007189.