Objective: To assess the dynamics of cognitive functions (CF) under the influence of levodopa in PD patients

Background: Our research is devoted to an urgent problem-the study of cognitive impairments (CI) in PD. It is known that motor symptoms in PD change dramatically under the influence of levodopa, and his long-term use is associated with motor fluctuations. However, the effect of levodopa on non-motor manifestations of PD, in particular on CI remains an insufficiently studied issue.

Method: The randomized clinical study included 65 patients with PD 2.0-3.0 stages by Hoehn-Yahr scale. Participants were randomized into two groups. Neuropsychological examination (NSE) was carried out twice with an interval of 6 months: in group I-at the on and off phase of levodopa therapy, and in group II-at the off and on period, respectively. Assessment of CF was carried out using: Mini-Mental State Examination, Montreal Cognitive Assessment, Frontal Assessment Battery, Scales for Outcomes in PD-Cognition, Geriatric Depression Scale.

Results: According to the GDS scale, clinically pronounced depression was not detected.
In the 1group 6 months after the initial NSE, according to all scales, there is a statistically highly significant decrease of CF at the off phase of levodopa. Statistically significant changes were related to subtests for executive, visual-spatial functions, attention, speech, and memory subtest. PD patients of the 2group at the on period of levodopa demonstrated improved execution of subtests for visual-spatial functions, extensions of speech activity and the increase in delayed recall via MoCA; MMSE scale showed improvement of attention, calculation, increased speech activity; FAB test showed positive dynamics in assessing fluency, dynamic praxis and complex choice reaction; improved attention, memory and expansion of delayed recall on a Scopa-Cog.

Conclusion: Thus, based on the obtained data of a two-stage assessment of CF in PD patients, it can be concluded that the severity of CI in PD patients may be affected by L-DOPA therapy to a certain extent, as well as motor disorders.
In our opinion, the method of assessing CF in an on and off period of L-DOPA therapy allows us to more accurately diagnose the severity of CI, determine their subtype, and identify the presence of cognitive fluctuations in the early stages, which allows us to rationally approach the appointment of L-DOPA drugs.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/effects-of-levodopa-on-cognitive-functions-in-parkinsons-disease/