Do you say, “It’s on the tip of my tongue” more often than you used to? As we age, many experience lethologica, or – for those who aren’t New York Times crossword buffs – difficulty finding the right words.
If you do say this more often than you wish and are concerned you might be on the slippery slope to Alzheimer’s, you now have less to fear, thanks to new research findings.
The good news is that the ability to find the right words is a less important indicator of brain health than another factor of speech – how fast you talk.
Speech Clues to Future Alzheimer’s
When researchers compared the non-scripted speeches of President Reagan – who went on to develop Alzheimer’s disease- with those of President Bush, they revealed significant differences.
Over time, researchers found that he spoke fewer unique words and used more non-specific nouns like "thing" when he could not think of the right word. President Reagan also used more conversational fillers and repeated himself more. None of these speech pattern irregularities were apparent with President Bush senior.
The length and frequency of pauses, short and clipped sentences, sentence complexity, repetition of phrases, and more could reveal a “speech fingerprint,” a distinctive signal that the brain is undergoing changes that will lead to Alzheimer’s disease.
One such change in speech is a word-finding difficulty. But this is so common that it has its clinical name—“tip-of-the-tongue (TOT) state.” This may be a normal part of aging. Researchers tested this and another aspect of speech that might indicate cognitive decline—talking speed.
The Picture-Word Interference Task
The new study from Baycrest and the University of Toronto was one of the first to examine differences in natural speech and brain function among healthy adults.
Researchers instructed 125 healthy volunteers aged 18 to 90 to complete three online assessments. The first assessment used a novel picture-word interference task, in which participants answered questions about the pictures they were looking at while ignoring distracting words they heard through headphones.
For example, when looking at a picture of a mop, researchers might ask, “Does it end in ‘p’?” while hearing the word “broom” as a distraction. In this way, the researchers could separate naming an object into its two parts: finding the correct word to describe the picture and then verbally saying it.
In the second test, the team recorded the volunteers as they described two complex pictures for 60 seconds each. The scientists analyzed their language performance using AI. Among other things, researchers examined how fast each participant spoke and how frequently they paused.
Finally, they undertook standard tests of mental abilities that tend to decline with age and are linked to dementia risk –executive function, which is the ability to manage conflicting information, stay focused, and avoid distractions.
The findings of the three assessments came as a surprise.
Speed More Important Than Word Finding
The team showed that many abilities, such as word-finding speed, declined with age. This was expected. It was unexpected that although the ability to recognize a picture and recall its name both worsened with age, this was not linked to a decline in other mental abilities. Nor was the number and length of pauses to find words.
Instead, how fast the study participants could name pictures predicted how fast they spoke generally, and both were linked to executive function. In other words, it wasn’t pausing to find words that showed the most vital link to brain health but the speed of speech surrounding pauses.
So, don't be concerned if you find yourself pausing to search for a word. This is probably a normal part of aging. On the other hand, slowing down normal speech, regardless of pausing, may be a more important indicator of changes to brain health, as confirmed by Jed Meltzer, the study's lead author.
“Our results indicate that changes in general talking speed may reflect changes in the brain. This suggests that talking speed should be tested as part of standard cognitive assessments to help clinicians detect cognitive decline faster and help older adults support their brain health as they age.”
