Verbal and visual memory in patients with early Parkinson's disease: Effect of levodopa

Background: The effect of initiation of levodopa therapy on the memory functions in patients with Parkinson's disease remains poorly understood.
Aims: To evaluate the effect of initiation of levodopa therapy on memory, in patients with early Parkinson's disease.
Settings and Design: Prospective case control study.
Materials and Methods: Seventeen patients with early Parkinson's disease were evaluated for verbal memory using Rey's auditory verbal learning test, and visual memory using the Benton's visual retention test and Form sequence learning test. UPDRS scores, Hoehn and Yahr's Staging and Schwab and England scores of Activities of daily living. Hamilton's depression rating scale and MMSE were also evaluated. Six controls were also evaluated according to similar study protocol. Levodopa was then prescribed to the cases. Same tests were repeated on all the subjects after 12 weeks.
Results: The mean age of the patients was 59.8 (± 12.9 yrs); mean disease duration of 3.26 (± 2.06 yrs). The mean UPDRS scores of patients were 36.52 (± 15.84). Controls were of a similar age and sex distribution. A statistically significant improvement in the scores on the UPDRS, Hamilton's depression scale, Schwab and England scale, and a statistically significant deterioration in the scores of visual memory was observed in patients with PD after starting levodopa, as compared to their baseline scores. There was no correlation between degree of deterioration and the dose of levodopa.
Conclusion: Initiation of levodopa therapy in patients with early and stable Parkinson's disease is associated with deterioration in visual memory functions, with relative preservation of the verbal memory.