Early indicators of cognitive decline, particularly related to Alzheimer’s disease, may be found in the nuances of speech, rather than solely in the content of what individuals say. A study conducted by researchers at the University of Toronto in 2023 highlights the significance of the pace of everyday speech as a potential predictor of cognitive health.
The research suggests that as people age, the rate at which they speak could be a more reliable marker of cognitive function than difficulties in word retrieval. This phenomenon, known as lethologica—or the “tip of the tongue” experience—can affect individuals across all age groups. However, it becomes increasingly prominent in those over the age of 60, when recalling names and words can pose greater challenges.
To investigate this further, the University of Toronto team assessed 125 healthy adults aged between 18 and 90. Participants were tasked with describing a scene in detail, after which they viewed images of common objects while listening to audio designed to either assist or confuse their recall. For instance, when shown a picture of a broom, they might hear the word “groom,” a tool to trigger memory through rhyme. Conversely, they might hear a related term like “mop,” which could mislead their thought process.
The study found that participants who spoke more quickly tended to generate responses faster in the subsequent task. These results align with the “processing speed theory,” which posits that a general slowdown in cognitive processing is central to cognitive decline, rather than a specific decline in memory functions.
According to Hsi T. Wei, a psychologist leading the study, “It is clear that older adults are significantly slower than younger adults in completing various cognitive tasks, including word-production tasks such as picture naming, answering questions, or reading written words.” The research also indicated that older adults exhibited more speech dysfluencies, including both unfilled and filled pauses, and generally spoke at a slower rate.
In a related commentary in 2024 for The Conversation, dementia researcher Claire Lancaster noted that this study represents a significant advancement in understanding cognitive changes, stating, “It’s not just what we say but how fast we say it that can reveal cognitive changes.” This perspective opens new avenues for exploring how speech patterns can indicate underlying cognitive health.
Recent advancements in artificial intelligence have also contributed to this field. Some algorithms have demonstrated the capability to predict an Alzheimer’s diagnosis with an accuracy of 78.5 percent based solely on speech patterns. Furthermore, other studies have indicated that individuals exhibiting more signs of amyloid plaques in their brains are 1.2 times more likely to experience speech-related issues. Amyloid plaques are recognized as a hallmark of Alzheimer’s disease.
In another study conducted by researchers at Stanford University in 2024, findings revealed that longer pauses and slower speech rates correlate with higher levels of tangled tau proteins, another significant indicator of Alzheimer’s pathology.
The authors concluded, “This suggests that speech changes reflect the development of Alzheimer’s disease pathology even in the absence of overt cognitive impairment.”
As research continues, scientists are making strides in decoding the subtleties of human speech to better understand what our verbal expressions reveal about our cognitive health. The findings from the 2023 study, published in the journal Aging, Neuropsychology, and Cognition, lay the groundwork for further exploration in this critical area of study.
