Slowed speech may indicate cognitive decline more accurately than forgetting words

By Claire Lancaster, Alice Stanton, University of Sussex

Can you pass me the whatchamacallit? It’s right over there next to the thingamajig.

Many of us will experience “lethologica”, or difficulty finding words, in everyday life. And it usually becomes more prominent with age.

Frequent difficulty finding the right word can signal changes in the brain consistent with the early (“preclinical”) stages of Alzheimer’s disease – before more obvious symptoms emerge. However, a recent study from the University of Toronto suggests that it’s the speed of speech, rather than the difficulty in finding words that is a more accurate 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 subsequently analysed by artificial intelligence (AI) software to extract features such as speed of talking, duration of pauses between words, and the variety of words used.

Participants also completed a standard set of tests that measure concentration, thinking speed, and the ability to plan and carry out tasks. Age-related decline in these “executive” abilities was closely linked to the pace of a person’s everyday speech, suggesting a broader decline than just difficulty in finding the right word.

A novel aspect of this study was the use of a “picture-word interference task”, a clever task designed to separate the two steps of naming an object: finding the right word and instructing the mouth on how to say it out loud.

During this task, participants were shown pictures of everyday objects (such as a broom) while being played an audio clip of a word that is either related in meaning (such as “mop” – which makes it harder to think of the picture’s name) or which sounds similar (such as “groom” – which can make it easier).

Interestingly, the study found that the natural speech speed of older adults was related to their quickness in naming pictures.

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