Speech Treatment and Parkinson’s: Do We Underestimate Cognitive Effort?

Hypophonia (low volume) is a common voice symptom associated with Parkinson’s disease (PD), and in fact, is now thought to be a prodromal symptom, that is, present even before the motor symptoms which lead to a diagnosis, so referral to speech therapy soon after diagnosis may be beneficial for most patients.

Even though hypophonia is thought to be a symptom of thoracic and laryngeal muscle stiffness, most people with PD, especially early in the disease, can speak louder in response to an external cue. So, for many years now, vocal intensity has been the focus of most speech therapy programs, including LSVT® LOUD, with evidence that focus on a single motor aspect of speech production can often yield improvement in overall speech clarity. Individuals with PD have also been reported to have difficulties in perceiving deficits in their own speech and self-monitoring may not be accurate so there is also a goal of recalibrating individuals to the level of effort they must employ to reach and maintain a more normal level of loudness. Throughout treatment patients are instructed to think “loud” and complete tasks with a “loud, good quality” voice.

But do all Parkinson’s patients with motor speech symptoms, including hypophonia, benefit from the same therapy program, or are there additional factors that should be considered when selecting a therapy approach?

Patient-Centered Treatment

Studies have indicated that various personality factors can interact with voice use and self-perception of effort. These individual differences or “person specific factors” have not always been incorporated into research studies but may be an important consideration when attempting to identify the best voice therapy approach for individual patients.

The introvert, for example, who says from the initial evaluation: “I was never loud,” “I don’t like loud people,” I have always been a “soft talker,” may resist the cue to “think loud,” and report fatigue due to the increased effort. Other voice patients with Parkinson’s who have mild cognitive impairment, may have difficulty generalizing the target of loudness to conversational speech when the dual demands of self-monitoring speech production and processing and formulating thoughts becomes too difficult.

Some voice patients may have difficulty differentiating cognitive load from vocal load, and consequently may report increased vocal effort when in fact they are truly experiencing increased cognitive effort because they possess fewer cognitive resources to manage communication situations.

Research now suggests that mental effort and vocal effort are strongly related,(i) and while we may not yet have a reliable method of measuring this relationship, it appears that it should be an important consideration when developing and delivering speech and voice therapy to individuals with Parkinson’s including further understanding of the type of cue which elicits louder speech with the least amount of cognitive load for the patients.  

The initial interview and speech/voice assessment of an individual with Parkinson’s is the opportunity to probe with questions that might help to differentiate personality characteristics, self-perception of vocal effort, and response to various cueing strategies. Motivation, self-efficacy, and cognitive function are also important factors that should guide treatment decisions, which may include a behavioral approach such as LSVT® LOUD or SPEAK OUT! or a device intervention such as SpeechVive.

(i) Miriam van Mersbergen, Lisa A. Vinney & Alexis E. Payne (2019): Cognitive influences on perceived phonatory exertion using the Borg CR10, Logopedics Phoniatrics Vocology, DOI:10.1080/14015439.2019.1617895

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Join me this coming Saturday, November 14, 2020, at 10:00 am ET for a virtual meeting and discussion with the Tampa Bay Area Spasmodic Dysphonia Support Group for people with spasmodic dysphonia and related voice conditions.

Spasmodic dysphonia (SD) is classified as a movement disorder, and is a focal dystonia/spasm affecting the muscle of the larynx causing one’s voice to sound strained or breathy. SD can co-occur with vocal tremor, cervical dystonia, and also may be a voice symptom associated with another movement disorder such as Parkinson’s or PSP. For additional information you can contact: Tampa Bay Spasmodic Dysphonia Support Group Leaders

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