Research: Speech and Dementia
CHP Professor Linda Carozza, PhD, and Rachel Melamudov '19 are investigating speech patterns to better understand the progression of dementia.
Dementia, a broad category of brain diseases associated with aging, affects nearly 50 million people per year. As life expectancy continues to increase globally, dementia is considered to be on the rise among the population as a whole. According to the non-profit Alzheimer's Association, Alzheimer's disease and other dementias will cost the United States $277 billion in 2018, a figure that could rise to a whopping $1.1 trillion by 2050 if present trends persist and no cure is found.
One of the major ways in which dementia debilitates the human brain is through loss of speech ability. Hypothesizing that investigating the breakdown of speech could be crucial to understanding how brain diseases progress, CHP Associate Professor and Director of the Communication Sciences and Disorders program Linda Carozza, PhD, has been studying temporal structure in speech as it relates to individuals with dementia.
“When we talk, it’s a natural phenomenon—we don’t think about the words as they flow from our mouth when we’re making sentences,” says Carozza. “That includes adjustments in the pronunciation of certain sounds.”
Carozza explains that the letter e, for example, can vary in pronunciation length depending on the word it is embedded in—a phenomenon language scientists refer to as voicing.
“If I say ‘hat’ and ‘had’, or ‘bet’ and ‘bed’, you can easily see that the word that ends with d is longer,” says Carozza. “That’s an automatic speech adjustment we make. In normal English speakers, this does not change with age. In the dementia hypothesis, the speech timing rules do not apply. “
As Carozza notes, the speech timing rules in individuals with dementia begin to break down and meld together, eventually producing slurring or unintelligibility, which can ultimately lead to a complete loss of speech ability.
While there is ample dementia research in fields such as memory loss and general confusion, there isn’t as much literature in temporal structure changes and speech deterioration. To better understand this phenomenon, Carozza enlisted Communication Sciences and Disorders student Rachel Melamudov ’19 to assist with the research, with help from the Division of Student Success’ Undergraduate Student/Faculty Research Program.
“I was analyzing the vowel lengths in difference utterances people were saying,” says Melamudov. “By measuring that speech I really got to listen more than the average undergraduate student in this type of program. You can hear those differences, and to have this type of experience very early on is an amazing opportunity.”
The vowel length measurements, says Carozza, are to determine whether or not individuals with dementia, or dysarthria (the specific disease that the duo is focusing on) are able to distinguish contrasts in vowels.
“The reason why Rachel is measuring these vowels, is because we suspect by the hypothesis that vowel contrasts will not be there—they will be more minimalizing, and sound more similar,” says Carozza.
Carozza and Melamudov are still in the analytical phase of the research, but they have already been able to examine some of the data to observe trends that might ultimately help them reach an impactful conclusion.
“So far, it seems very fruitful in terms of mild to moderate staging, because patients in more severe stages could not do this task at all. That lends credibility to it being able to predict changes before the disease has well advanced,” says Carozza.
The duo is waiting for more information to make any precise scientific statement about the results, but their work so far has been promising—and while the research is simply a fish in a vast ocean of dementia-related research, its uniqueness can help uncover some major issues associated with cognitive decline.
“This is a small aspect of a huge, multi-billion dollar industry. But I’m doing it from the standpoint of speech science, which has not had the forefront in the dementia world,” says Carozza “There is room for us, and it’s going to be a growing demographic—it already is.”
Melamudov stresses that given the fact that there is no known cure, and that millions of people across the world are being diagnosed with various forms of dementia each month, their work also aims to spur an immediate impact in terms of creating favorable conditions for patients and their families.
“This project is definitely centered on this disorder, but we’re also hoping it creates more of a discussion about quality of life with individuals with dementia,” says Melamudov.
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