Can you pass me the whatchamacallit? It’s right there next to the thingamajig.
Many of us will experience “lethologica” or word finding difficulty in everyday life. And it usually becomes more prominent as we get older.
Having trouble finding the right word on a regular basis may indicate changes in the brain consistent with the early (“preclinical”) stages of Alzheimer’s disease, before the most obvious symptoms appear.
However, a recent study from the University of Toronto found that the speed of speech, not the effort it takes to find words, is a better indicator of brain health in older adults.
The researchers asked 125 healthy adults, aged 18 to 90, to describe a scene in detail. Recordings of these descriptions were then analyzed by artificial intelligence (AI) software to extract features such as the speed of speech, the length of pauses between words, and the variety of words used.
Participants also completed a standard battery of tests that measured concentration, thinking speed, and the ability to plan and carry out tasks. Age-related declines in these “executive” skills were closely linked to the rate of a person’s daily speech, suggesting a broader decline than just difficulty finding the right word.
A novel aspect of this research was the use of a ‘picture-word interference task’, a clever task designed to separate the two steps of naming an object: finding the correct word and instructing the mouth how to say it aloud.
During this task, participants were shown pictures of everyday objects (such as a broom) while hearing an audio clip of a word that either had a related meaning (such as “mop,” which may make it harder to think of the name of the picture) or that sounded similar (such as “groom,” which may make it easier).
Interestingly, the study found that older adults’ natural speech rate was related to their speed at naming pictures, highlighting that a general slowing in processing may underlie broader cognitive and linguistic changes with age, rather than a specific challenge in retrieving words from memory.
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How the findings can be made more powerful
Although the findings of this study are interesting, word retrieval in response to pictures may not reflect the complexity of vocabulary in casual, everyday conversations.
Verbal fluency tasks that require participants to think of as many words as possible from a certain category (e.g. animals or fruits) or to start with a specific letter within a certain time can be combined with pictures to better capture the ‘tip-of-the-tongue’ phenomenon.
The tip-of-the-tongue phenomenon refers to the temporary inability to recall a word from memory, despite partially remembering the word and feeling that one knows it.
These tasks are considered to be a better test of everyday conversation than the picture-word interference task because they require the active retrieval and production of words from one’s vocabulary, similar to the processes involved in natural speech.
Although verbal fluency does not decline significantly with age (as shown in a 2022 study), poor performance on these tasks may indicate neurodegenerative diseases such as Alzheimer’s.
The tests are useful because they account for typical changes in the ability to remember words as people age. This allows doctors to detect impairments beyond those expected with normal aging and potentially detect neurodegenerative disorders.
The verbal fluency test targets several brain areas involved in language, memory and executive functions. The test can therefore provide insight into which brain areas are affected by cognitive decline.
The authors of the University of Toronto study could have examined participants’ subjective experiences of word-finding difficulties alongside objective measures such as pauses in speech. This would have provided a more comprehensive understanding of the cognitive processes involved.
Personal reports of the “feeling” of having difficulty with word finding can provide valuable insights to complement behavioral data, potentially leading to more powerful tools for quantifying and detecting early cognitive decline.
Opening doors
Still, this study has opened up interesting avenues for future research, showing that not only what we say, but also how quickly we say it, can reveal cognitive changes.
By leveraging natural language processing technologies (a form of AI), which use computational techniques to analyze and understand human language data, this work builds on previous research that noted subtle changes in the spoken and written language of public figures such as Ronald Reagan and Iris Murdoch in the years before their dementia diagnoses.
While these opportunistic reports were based on retrospective observations following a dementia diagnosis, this study offers a more systematic, data-driven, and forward-looking approach.
Rapid advances in natural language processing allow for automatic detection of language changes, such as speech rate slowdown.
This study highlights the potential of speech rate changes as an important, yet subtle, indicator of cognitive health that can help identify people at risk before more serious symptoms become apparent.
Claire Lancaster, Lecturer in Dementia, University of Sussex and Alice Stanton, PhD candidate in Dementia, University of Sussex
This article is republished from The Conversation under a Creative Commons license. Read the original article.
An earlier version of this article was published in March 2024.