Score spread and average better track brain thickness in older adults
An observational study of 318 older adults favored analyzing differences across cognitive test scores alongside average performance, rather than combining them into a ratio.
2 years, cohort study
Limit: Statistical comparison methods did not consistently favor the same model
Edited by Boris Djordjevic · AgingResearch.News
In an observational study, 318 older adults had normal cognition or mild cognitive impairment—cognitive difficulties with everyday independence preserved. Their average age was 70.7, and 61% were female. Researchers analyzed 21 measures from 16 cognitive tests and brain scans. They compared two ways of measuring unevenness across test scores: the standard deviation, a measure of spread, and that spread divided by the average score.
Considering spread alongside average performance better accounted for thickness of the entorhinal cortex, a brain region involved in memory, than the ratio did. Among people with lower average scores, less spread was linked to greater thickness in the left entorhinal cortex. This link was weaker at higher average scores. The authors suggested that the spread measure offered a more valid way to quantify uneven performance, using sufficiently comprehensive test batteries.
Why it matters
Uneven cognitive performance is being studied as a possible marker of cognitive decline. Standardizing its measurement could help researchers evaluate its usefulness for tracking cognitive aging.
Caveats
The observational brain comparisons did not test whether either measure predicts future cognitive decline, and statistical comparison methods did not consistently favor the same model. The study excluded people with dementia.
- Mild cognitive impairment
- Brain morphometry
- Coefficient of variation
- Cognitive dispersion
- Entorhinal cortex thickness
- Humans
The paper
National Taiwan University
Alzheimer's & Dementia, May 25, 2026, Open access
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