Acoustic analysis of parkinsonian speech II: L-Dopa related fluctuations and methodological issues.

The drug L-Dopa is used in the treatment of Parkinson's disease (PD), and patients often experience fluctuations in performance after a period of time taking L-Dopa. This paper reviews the literature pertaining to these fluctuations. While a number of researchers have examined L-Dopa related fluctuations in general, these fluctuations have rarely been addressed in speech research. To examine the effect of L-Dopa related fluctuations a number of methodological issues need to be addressed including time of day, anxiety level, disease stage, and drug regimen differences. Strategies are proposed for addressing these methodological issues in studying the effects of L-Dopa fluctuations on PD speech. This paper is part two of a two part series; Part one examined PD and PD speech in general, along with L-Dopa treatment, and the effects of L-Dopa treatment on speech.