Subtle changes in how someone speaks could be early indicators of Alzheimer’s disease, though researchers are still working to pinpoint exactly which aspects of speech are most telling.
The Indicator in Language
A 2023 study suggests that as people age, how they say something may be more important than what they say. Researchers at the University of Toronto believe the pace of everyday speech could be a better indicator of cognitive decline than difficulty finding the right words. “Our findings suggest that changes in overall speech rate may reflect changes in the brain,” said cognitive neuroscientist Jed Meltzer when the research was published.
“This suggests that speech rate should be tested as part of standard cognitive assessments to support doctors identify cognitive decline more quickly and support older adults in maintaining brain health as they age.”
What is Lethologica?
Lethologica, also known as the “tip-of-the-tongue” phenomenon, is a common experience for people of all ages. Though, recalling names can become more challenging with age, particularly after 60. To understand this, researchers asked 125 healthy adults, between the ages of 18 and 90, to describe a scene in detail.
Participants were then shown images of everyday objects while listening to audio designed to either confirm or confuse their recollections.
For example, if participants were shown a picture of a broom, the audio might say “broom,” helping them remember it through rhyme. Alternatively, the audio might offer a related word like “mop,” which could momentarily confuse the brain.
The faster a person speaks spontaneously in the first task, the quicker they are able to discover answers in the second task.
The results align with the “speed of processing” theory, which posits that a general slowing of cognitive processes underlies cognitive decline, rather than a specific slowing of memory centers. “older adults are significantly slower than younger adults in completing various cognitive tasks, including word production tasks such as naming pictures, answering questions, or reading words,” explained a team led by psychologist Hsi T. Wei of the University of Toronto.
The Signals
“In natural speech, older adults also tend to produce more disfluencies, such as empty and filled pauses (e.g., “uh” and “um”) between phrases, and generally have a slower rate of speech.”
In a 2024 article for The Conversation, dementia researcher Claire Lancaster said the Toronto study “opened up exciting avenues… demonstrating that it’s not just what we say, but how quickly we say it that can reveal cognitive changes.”
Recently, some artificial intelligence algorithms have used speech patterns to predict an Alzheimer’s diagnosis with 78.5% accuracy. Other studies have found that patients with more signs of amyloid plaques in the brain are 1.2 times more likely to have language problems. Amyloid plaques are a hallmark of Alzheimer’s disease, as are tangles of tau protein. In 2024, researchers at Stanford University conducted a study that found longer pauses and a slower rate of speech were associated with higher levels of tangled tau protein.
Neuroimaging recordings of 237 cognitively healthy adults suggest that those with higher levels of tau protein tended to have slower speech rates, longer pauses between sentences, and a greater number of pauses overall.
If this holds true, language patterns detected during memory recall tests could provide entirely new insights into a person’s neurological state, undetectable with traditional tests.
“This suggests that changes in language reflect the development of Alzheimer’s disease pathology even in the absence of obvious cognitive impairment,” the authors of the 2023 study conclude. “It may be particularly useful to examine language during delayed story recall in a memory task,” the team writes.

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