Acoustic analysis of voice and speech characteristics in presymptomatic gene carriers of Huntington's disease: Biomarkers for preclinical sign onset?

Purpose: The study compared presymptomatic carriers of expanded CAG repeat in the huntingtin gene with matched control participants to determine whether measures of speech motor variability and timing, already found to be significantly different in manifest Huntington's disease (HD), are significantly different for individuals at risk for HD. Measures included spectral characteristics of sustained vowel phonation, voice onset time, diadochokinetic variability, utterance duration, and speech rate changes. Method: Eighteen carrier participants and matched control participants performed diadochokinetic tasks, produced vowels, and repeated sentences at habitual and increased speed. Results: The carrier group showed significantly greater variability in syllable duration for intratrain coefficient of variation of duration; lower mean number of syllables per breath; lower diadochokinetic rates; lower mean duration for vowels; and higher mean jitter, shimmer, and noise-harmonic ratio (NHR). Backward stepwise logistic regression retained three variables in the model: intratrain coefficient of variation of duration, repetition rate for /pata/, and mean NHR. Discriminant analysis constructed a prediction equation. The discriminant function showed strong accuracy for classifying participants. Conclusions: Individuals at risk for HD showed increased speech variability, reduced repetition rate, and vocal instability. Speech rate, speech and vocal stability, and vocal endurance may ultimately be used to identify presymptomatic carriers for preclinical signs.