Subtle changes in speech are associated with early signs of Alzheimer’s disease in the brain

Early signs of Alzheimer's disease in the brain are linked to nuanced changes in speech patterns, according to an NIA-funded study published in Alzheimer's & Dementia. The findings showed that certain speech changes may occur before cognitive decline, suggesting that speech markers could be used to help health care providers diagnose Alzheimer's earlier in the disease progression.

Speech problems, such as repeating questions and having a hard time finding the right words, are among the most common self-reported cognitive concerns in older adults. Previous research has shown that speech changes are a feature of mild cognitive impairment and Alzheimer's. However, it was unclear whether speech changes may be linked to early signs of Alzheimer's in the brain, even before cognitive symptoms appear. A team of researchers from Stanford University, Boston University, and the University of California, San Francisco examined how changes in speech patterns relate to Alzheimer's biomarkers in the brain.

The researchers analyzed Framingham Heart Study data from 238 adults with normal cognition. As a part of the Framingham study, the participants completed cognitive testing and underwent PET brain scans to measure changes in amyloid and tau, two proteins linked to Alzheimer's. The cognitive testing incorporated spoken responses to questions and was recorded, enabling researchers to analyze the speech patterns of participants. For the current study, researchers analyzed speech patterns as Framingham participants responded to a memory task in which they were asked to recall aspects of a story they were told 20 minutes before.

The scientists found that speaking more slowly, and speaking with longer and more frequent pauses, was linked to an increase in tau protein in two areas of the brain: the medial temporal region and the early neocortical region. Notably, the memory score itself was not associated with tau protein, which suggests that speech changes may be early signs of Alzheimer's before changes in memory occur.

Overall, the study shows that subtle changes in speech during a memory test may indicate early Alzheimer's-related changes in the brain. The study findings are limited in that speech patterns during a memory test may not accurately reflect speech patterns in everyday life. Additional studies may address this limitation by examining the link between tau protein and speech patterns in various real-world contexts. Further research may also explore whether early changes in speech are associated with a person's risk for cognitive decline.

This research was supported in part by NIA grants K99AG071837, P30AG066515, R01AG033040, R01AG049607, R01AG016495, RF1AG062109, RF1AG072654, and U19AG068753.

These activities relate to NIH's AD+ADRD Research Implementation Milestone 9.H, "Launch research programs to develop and validate sensitive neuropsychological and behavioral assessment measures to detect and track the earliest clinical manifestations of AD and AD-related dementias."

Reference: Young CB, et al. Speech patterns during memory recall relates to early tau burden across adulthood. Alzheimer's & Dementia. 2024;20(4):2552-2563. doi:10.1002/alz.13731.