Handwriting and speech changes across the levodopa cycle in Parkinson's disease

Levodopa treatment is used to reduce rigidity and bradykinesia in Parkinson's disease (PD). This study tracked the handwriting and speech performance of 10 PD patients at 30-minute intervals across one levodopa drug cycle to evaluate levodopa-related changes in temporal and spatial measures that are assumed to correspond to changes in rigidity and bradykinesia. The handwriting measures included l and e upstroke duration and size. The speech measures included duration of the vowels /i/, /u/, /ae/, and /[symbol: see text]/ and the quadrilateral area produced by these vowels, and the slope of the diphthong /aI/. Levodopa significantly improved handwriting upstroke duration but not upstroke size. Speech measures did not show a significant trend across the levodopa cycle. The results suggest that upstroke duration is sensitive to the presumed effects of levodopa and that handwriting analysis may hold promise in helping to estimate an optimum levodopa regimen for PD patients.