Variability in fundamental frequency during speech in prodromal and incipient Parkinson's disease: a longitudinal case study.

Nearly two centuries ago, first observed that a particular pattern of speech changes occur in patients with idiopathic Parkinson's disease (PD). Numerous studies have documented these changes using a wide variety of acoustic measures, and yet few studies have attempted to quantify any such changes longitudinally, through the early course of the disease. Moreover, no attempt has been made to determine if speech changes are evident during the prodromal period, prior to the onset of clinically noticeable symptoms. This case-control pilot study is a first attempt to determine if changes in fundamental frequency variability during speech, an acoustic measure known to be affected later in the course of the disease, are evident during the prodromal period. A retrospective analysis of videotape footage recorded and made available by a leading national television news service. Videotape samples were obtained for a single individual (and a well-matched control subject) over an 11-year period of this individual's life (7 years prior to diagnosis of PD, and 3 years post-diagnosis). Results suggest that changes in F0 variability can be detected as early as 5 years prior to diagnosis (consistent with findings from other laboratories that have relied on cross-sectional study approaches). This pilot study supports the utility of such a design approach, and these results warrant continued effort to better understand the onset of PD and sensitivity of measurement of voice acoustical changes during the prodromal period.