Everyday speech can tell you more about brain health than tests can

Researchers from Baycrest, the University of Toronto and York University have found that even the smallest features of spoken language - such as pauses, hesitations, parasitic words ("eh", "well"), and rate of utterance - are closely linked to so-called executive functions of the brain responsible for memory, planning and flexibility of thinking.

The work, published in the Journal of Speech, Language, and Hearing Research, was one of the first to show a direct link between natural speech patterns and human cognitive abilities. This opens up new possibilities for diagnosing brain disorders and early detection of dementia.

"Speech is not just a matter of style, but a sensitive indicator of brain health," notes Dr Jed Meltzer, lead author of the study and senior research fellow at Baycrest's Rothman Institute for Research.

How speech reflects brain function

In the experiment, participants were asked to describe complex illustrations in their own words, after which they took standardised tests to assess executive function. Using artificial intelligence, the scientists analysed the audio recordings, identifying hundreds of parameters - pause length, frequency of parasitic words, speech rhythm and rate of utterance.

The analysis showed that these speech features predicted the results of cognitive tests with high accuracy, even after taking into account age, gender and level of education.

Executive functions are known to decline with age and are often impaired in the early stages of dementia. However, traditional tests do not always accurately track these changes: they take time, depend on the experience of the participant and are subject to a 'habituation' effect.

A new tool for early diagnosis

Unlike laboratory tests, natural speech is a habitual and easily measurable behaviour that can be analysed repeatedly, without pressure and under real-life conditions. It allows the speed of information processing - an important indicator of cognitive health - to be monitored without the need for artificial time limits.

"Our results pave the way for new tools that can monitor changes in cognitive function in clinics or even at home. Early diagnosis is particularly important because dementia develops gradually, and intervening in the first stages can slow its progress," Dr Meltzer emphasises.

The scientists call for long-term follow-up to monitor the speech of the same people over the years and to distinguish natural ageing from early signs of disease. In the future, they plan to combine speech analysis with other biomarkers to make diagnosis more accurate and affordable.