Original title: Association of Amyloid and Tau With Cognition in Preclinical Alzheimer Disease
Researchers repeatedly scanned the brains of 60 older adults who were clinically normal and tested their thinking each year. The scans tracked amyloid plaques and tau tangles, two brain changes linked to Alzheimer disease. Rising amyloid came before changes in tau, and changes in tau were linked to changes in thinking. People whose tau rose more were more likely to progress to mild cognitive impairment, a noticeable decline in thinking.
Imagine checking a garden over several seasons. A patch of weeds appears, then another change follows, and later the plants begin to struggle. It is hard to tell which change came first if you only look once. In this paper, repeated garden checks stand for repeated brain scans, while the weeds, later change, and struggling plants stand for amyloid, tau, and changes in thinking.
Alzheimer’s changes can build in the brain before a person has clear symptoms. In this small group of older adults, repeated scans linked amyloid increases to later tau changes, and tau changes to shifts in cognition—information that may help researchers choose what to measure in prevention trials.
The findings come from 60 clinically normal older adults who had multiple amyloid and tau scans, drawn from a larger study. They show associations and a statistical mediation pattern, not proof that amyloid causes tau changes or that tau causes cognitive decline. The abstract does not establish whether the findings apply to other groups or whether tracking these scans improves prevention or treatment.
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Association of Amyloid and Tau With Cognition in Preclinical Alzheimer Disease — Bernard Jimmy Hanseeuw, Rebecca A. Betensky, Heidi I.L. Jacobs et al. — JAMA Neurology — doi:10.1001/jamaneurol.2019.1424
Abstract licence: CC BY
Explanation generated by Synthesis from the abstract — it is not the original paper.