BACKGROUND: Untreated Parkinson's disease (PD) patients display speech abnormalities characterized by narrow range of fundamental frequency (Fo) variation and higher amplitude. The role of dopaminergic systems in the pathogenesis of these changes as well as the therapeutic effect of L-dopa have not been clearly determined. The aim of this study is to assess the effect of L-dopa on the prosodic features of the speech of female PD patients. METHOD: We have studied 8 PD female patients (63.5 ± 6.8 years). The PD patients (H-Y stage 2, seven subjects; stage 2.5, four patients; stage 1, one patient) were examined when off and on. The fundamental frequency, intensity and duration of five affirmative sentences were analysed with the software WinPitch 1.8 (Philippe Martin®). The analysed Fo parameters were: usual Fo (Fo us), maximal Fo (Fo max), minimal Fo (Fo min), Fo max of the prenuclear tonic (Fo max PNT), Fo min of the prenuclear tonic (Fo min PNT), Fo max of the nuclear tonic (Fo max NT), Fo min of the nuclear tonic (Fo min TN), velocity of melodic variation of the PNT (VPNT), velocity of melodic variation of the NT (VNT), amplitude of melodic variation of the PNT (APNT), and amplitude of melodic variation of the NT (ANT). Duration of the statement (D), duration of the PNT (DPNT), duration of the NT (DNT) and number of syllables per second (NSS) were the duration parameters investigated. The following intensity variables were studied: mean intensity (MI), maximal intensity (I max), minimal intensity (I min), intensity of the PNT (IPNT) and intensity of the NT (INT). Differences were statistically significant if p<0.05. RESULTS: When on, PD patients had significantly higher Fo max PNT (201.9 ± 27.5 Hz), higher APNT (22.1 ± 18.7 Hz), and smaller MI (32. ± 6.2 dB) in comparison with off period (respectively: 168.5 ± 83.5 Hz, 20.4 ± 12.1 Hz, 32.7 ± 5.6 dB). CONCLUSION: Our findings show that L-dopa replacement therapy slightly improves the Fo range and the intensity of speech of Brazilian female PD patients. These results suggest that non-dopaminergic systems are probably involved in the pathogenesis of prosody changes in PD. They also indicate that therapies other than dopaminergic agents are warranted to treat speech abnormalities in PD.
Parkinson's disease; L-dopa; fluctuations; prosody; phonoaudiology; voice; speech
