Perceived changes in speech due to Parkinson’s, not aging: Study
Vocal quality declines naturally across life, but this disease likely adds layers
Age-related declines in speech processes do not appear to contribute to the voice disturbances perceived by people with Parkinson’s disease, and are more likely due to disease processes themselves, a study reports.
“Reduced self-voice perception in [Parkinson’s] is likely due to [Parkinson’s]-specific sensory feedback deficits, rather than age per se,” the researchers wrote.
Standard patient-reported measures of perceived changes in voice quality used in this study, however, fail to adequately capture the complexity of Parkinson’s symptoms, the team noted, “underscoring the need for more specific and accurate assessment tools to evaluate voice self-perception in this population.”
The study “Investigating How Age Affects Self-Perception and Voice Awareness in Parkinson’s Disease,” was published in the Journal of Voice.
Sensory feedback determines perception of problems in processes like speech
Speech disturbances, such as a hushed voice, reduced pitch range, or trouble with articulation, are common among people with Parkinson’s. While the disease’s motor symptoms contribute to these vocal problems, impaired sensory feedback, which limits the perception of voice changes, can diminish a person’s awareness of speech errors.
“A better understanding of these sensory feedback deficits is essential, as they may be the key to understanding speech and voice control difficulties in communication as experienced by [people with Parkinson’s],” the researchers wrote.
Aging naturally affects the systems involved in voice production due to anatomical changes within the larynx, or voice box, such as muscle shrinkage and low mucus production. These changes result in poorer voice quality, vocal strain, and altered pitch.
However, it’s unclear whether the combined effects of age and Parkinson’s worsen deficits in voice self-perception and awareness.
Researchers in Chile, Spain, and the Netherlands recruited 80 Spanish-speaking participants, ages 57 to 83, across three Chilean outpatient healthcare centers.
Among them, 27 had Parkinson’s with at least one motor impairment affecting speech clarity (average age of 70), and 28 were healthy adults (average age of 66). The remaining 25 people had been diagnosed with general voice disorders unrelated to Parkinson’s (average age of 66). These disorders included a change in voice quality, a complete loss of voice, benign lesions in the larynx, and other conditions not directly related to speech.
Voice self-perception was assessed using three patient-reported outcome measures (PROMs): the Voice Symptoms Scale, Voice Handicap Index-10, and Voice-Related Quality of Life. Voice quality, particularly voice intensity, was measured by recording participants’ speech. A cepstral peak prominence (CPP) analysis assessed the severity of voice disorders, with lower values indicating worse voice disturbances.
Across all three PROMs, people with Parkinson’s showed lower self-perception and awareness of voice problems, while those with general voice disorders had the highest self-perception compared with healthy controls. Still, age did not significantly impact the self-perception of voice among Parkinson’s patients.
Tests fail to ‘capture the complexity’ of Parkinson’s varied symptoms
Voice intensity was highest for general voice disorder patients (mean of 64.66 decibels), followed by healthy controls (mean, 60.89 decibels), while Parkinson’s patients had the lowest voice intensity (mean, 58.20 decibels). Healthy controls exhibited the fewest voice disturbances, as reflected by the highest CPP scores (mean of 15.03), while people with general voice disturbances had a mean of 12.30, and those with Parkinson’s had the lowest score, a mean of 10.17.
PROM results showed significant differences between groups, “indicating considerable variability in these parameters across groups,” the team noted. Moreover, the voice disturbances group showed marked differences across all PROMs and voice measurements compared with healthy controls and Parkinson’s patients.
“Our findings indicate that the PROMs used in the current study do not adequately capture the complexity of both motor and non-motor symptoms in [Parkinson’s],” the researchers wrote.
A final clustering analysis, a statistical method for grouping similar data points, incorporating all PROM and voice measurement data, reinforced the overall findings, showing similar age distributions across clusters.
In this analysis, general voice disturbances associated with higher loudness and PROM scores. At the same time, the Parkinson’s and healthy control groups showed distinct patterns, suggesting that “[Parkinson’s] does not fit neatly into either the voice disorder or healthy categories,” the researchers said.
“A comparison of similar age groups indicates that changes in voice quality and reduced intensity in [Parkinson’s] are not directly associated with age-related sensory decline, but rather with specific [Parkinson’s] effects, including sensory deficits that may limit self-awareness of voice problems,” the scientists wrote.
“Future studies should focus on developing tailored PROMs to better capture these challenges in [people with Parkinson’s],” they added.
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