How Your Speech Can Unveil Your Brain’s Workings

Finding your words sometimes becomes more difficult while age. This phenomenon, although banal, arouses concerns, especially on the risk of neurodegenerative diseases like Alzheimer's. However, a study by researchers at the Byycrest Center and the University of Toronto, published in the journal Aging, Neuropsychology, and Cognition, calls into question that the forgetting of words is a precursor of cognitive decline. Our way of speaking would be the best revealer as to the state of our brain.

Their work, based on the analysis of the speech of 125 adults thanks to artificial intelligence, reveals a more reliable indicator: speech speed. A slowdown in verbal flow could reflect brain functions before the appearance of more marked symptoms. These results open up new perspectives for early detection of cognitive disorders and question the current methods of evaluation of neurodegenerative diseases.

A fine language analysis thanks to AI

To assess the link between speech and cognitive health, researchers followed 125 adults aged 18 to 90. Their objective: to identify early markers of cognitive decline by analyzing speech flow using artificial intelligence tools.

Participants spent three types of linguistic tests. First, they had to describe in detail a complex scene for 60 seconds. AI software then analyzed the speech speed, the frequency and duration of the breaks, as well as the lexical diversity used. Then, an image-word interference test was carried out. Participants had to name illustrated objects while being distracted by words pronounced in a helmet. Some words had a semantic link with the image: see a broom and hear “mop”. Others had a phonological link: see a broom and hear “ballet”. This test made it possible to assess the capacity of the brain to process and recover the words in the presence of competing information. Finally, participants were subjected to conventional cognitive tests. In particular, they evaluated executive functions, essential for planning and decision -making.

The results have shown that speaking more slowly, the general slowdown in verbal flow, was directly correlated to a drop in executive functions. As Dr. Jed Meltzer, principal researcher of the study explains: ” Our results indicate that changes in speech speed can reflect changes in the brain ».

An essential difference for the brain, between slowdown and breaks

We have all already experienced this moment when a word seems to escape us, suspended at the end of our language. With age, these oversights become more frequent, which can arouse concern about cognitive health. However, according to researchers, this phenomenon, called Lethologica, is not a sign of a neurological problem. It is not the forgetting of the words that must worry, but the way we speak daily. Clearly, a person can take breaks to look for their words while maintaining a fluid rhythm of speech. Conversely, someone who speaks more slowly, even without marked hesitation, could present a beginning of cognitive decline.

For what ? Because speaking is a demanding task for the brain. It requires rapid coordination between thought, memory and articulatory muscles. If the brain takes more time to organize information and produce fluid discourse, this may indicate a drop in executive functions. In other words, the ability to plan, adapt and process several information simultaneously.

However, this approach based on objective measures such as speech speed and the frequency of breaks could be enriched by an analysis of the subjective experiences of the participants. As the authors of the study point out, it would have been relevant to collect individual feelings on the difficulty of finding the words, in parallel with behavioral observations.

These personal reports on the “feeling” of difficulty in speaking could shed complementary light on the cognitive mechanisms at stake. By combining objective data and subjective perceptions, researchers could develop even more precise tools to detect the early signs of cognitive decline, and better differentiate normal brain aging from a nascent neurodegenerative disorder.

Towards new early detection tools on the health of our brain

So if speaking more slowly can reflect brain aging, how to exploit this discovery in medicine? Until now, the diagnosis of cognitive disorders is based on standardized tests and clinical observations. But too often, they are done when the symptoms are already well installed.

Thanks to advances in automatic language processing (NLP – Natural Language Processing) and AI, it is now possible to detect subtle changes in speech long before a clinical diagnosis is made.

Winterlight Labs, a company specializing in AI and neuroscience, collaborates with researchers to analyze the word from vocal recordings. Their technology makes it possible to automatically measure the speech speed, the length of the breaks and the grammatical complexity of a discourse. These data could allow doctors to identify the first signs of neurodegenerative diseases simply by analyzing a few minutes of conversation. Researchers also provide longitudinal studies to observe the evolution of verbal flow in patients over several years. The goal is to corroborate the link between gradual slowdown in the rhythm of speech and brain health.

But language analysis is not the only promising path. Artificial intelligence plays an increasing role in the early diagnosis of neurodegenerative diseases. A recent study at London University shows that it could also analyze retinal scans to detect early signs of cognitive decline. Can we then allow ourselves to imagine a near future, where simple examinations – whether it be speech analysis or an eye test – could allow much earlier detection of Alzheimer's and other forms of dementia, opening the way to faster and effective care.

Source: HSI T. Wei et al., “Cognitive Components of Agging-Related Increase in Word-Finding Difficult”, Aging, Neuropsychology, and Cognition, Volume 31, 2024-Issue 6