Speech Issues and Dementia

As life expectancy continues to increase globally, dementia—a broad category of brain diseases that affects nearly 50 million people per year—is on the rise.

And with it comes loss of speech.

Associate Professor Linda Carozza, PhD, hypothesizes that investigating the breakdown of speech could be crucial to understanding how brain diseases progress, which could ultimately lead to preventative treatments and improved quality of life measures.

“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, who studies temporal structure in speech, or speech timing, as it relates to individuals with dementia.

“That includes adjustments in the pronunciation of certain sounds. If I say ‘hat’ and ‘had,’ or ‘bet’ and ‘bed,’ you can easily hear that the word that ends with d is longer,” Carozza says. “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.”

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, Carozza says.

While there is ample dementia research around memory loss and general confusion, there is less about temporal structure changes and speech deterioration. Carozza, who directs Pace’s Communication Sciences and Disorders program, enlisted Rachel Melamudov ’19 to assist with her research.

“I analyzed and reported the length of various vowels from a myriad of recorded speech samples,” says Melamudov. Her measurements help determine whether the vowels of dementia patients are distinct from each other or sound more similar, Carozza says.

“The reason 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.

Through this research, Carozza is theorizing that the ability to firmly and automatically control speech timing represents a crucial distinction between healthy elderly individuals versus those with dementia—and that continuing to investigate this topic could lead to a significantly better understanding as to how the disease progresses. Carozza will present their work in May at the New York State Speech-Language-Hearing Association’s 59th Annual Convention in Albany.