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Home › Research › Topics › Biomarkers › ADNI correlations

How 49 ADNI biomarker and cognitive measures relate to each other

Across 49 measures and 1,176 pairs, 662 correlations survived Holm correction. CSF tau markers move almost in lockstep (rho +0.98), and executive function's link to amyloid shrinks once memory is accounted for.

Figures are derived from ADNI data under a Data Use Agreement. Only aggregate statistics are published; no individual participant records are shown.

The Alzheimer's Disease Neuroimaging Initiative (ADNI) is funded by the National Institute on Aging and contributions. This page is not endorsed by ADNI or the National Institute on Aging.

Every pair of the 49 baseline measures was correlated. Rho runs from −1 to +1: 0 means no relationship, +1 means the two measures rise together without exception, −1 means one falls as the other rises. With 1,176 tests, chance alone would produce many small p-values, so each p-value was adjusted with the Holm correction before a pair was called significant.

The strongest pairs

Strongest correlations: CSF total tau and CSF p-tau181 rho +0.98; Trail Making Test B and ADNI-EF executive composite rho -0.89; Plasma p-tau217/Aβ42 ratio and Amyloid PET (centiloids) rho +0.75 -1.0 -0.5 0 +0.5 +1.0 rho, −1 to +1 CSF total tau · CSF p-tau181 rho +0.98 Trail Making Test B · ADNI-EF executive composite rho -0.89 Plasma p-tau217/Aβ42 ratio · Amyloid PET (centiloids) rho +0.75

Bars to the right of zero are positive correlations, bars to the left negative.

  1. CSF total tau and CSF p-tau181 — rho +0.98
  2. Trail Making Test B and ADNI-EF executive composite — rho -0.89
  3. Plasma p-tau217/Aβ42 ratio and Amyloid PET (centiloids) — rho +0.75

The first two pairs are strong because they measure nearly the same thing. CSF total tau and p-tau181 are two assays of related tau species in the same fluid. Trail Making Test B is one of the tests that go into the ADNI-EF executive composite, and the sign is negative because a slower Trails B time means worse performance while a higher ADNI-EF score means better.

The third pair is the interesting one. A blood test, the plasma p-tau217 to Aβ42 ratio, tracks amyloid PET centiloids at rho +0.75. Blood and scanner are measuring the same underlying amyloid burden by very different routes.

Executive function and amyloid, adjusting for memory

ADNI-EF and CSF Aβ42: rho +0.33 unadjusted, +0.18 adjusted for memory (p < 0.001); ADNI-EF and Amyloid PET: rho +0.27 unadjusted, +0.11 adjusted for memory (p = 0.113) -1.0 -0.5 0 +0.5 +1.0 rho, −1 to +1 ADNI-EF · CSF Aβ42 rho +0.33 → +0.18 memory-adjusted, p < 0.001 ADNI-EF · Amyloid PET rho +0.27 → +0.11 memory-adjusted, p = 0.113
  • unadjusted
  • memory-adjusted, significant
  • memory-adjusted, not significant

The upper bar in each pair is the plain correlation; the lower bar is the partial correlation after adjusting for memory score.

Executive function correlates with both amyloid measures at first glance. Adjust for memory and most of that link disappears. With CSF Aβ42 the correlation falls from +0.33 to +0.18 and stays significant (p < 0.001). With amyloid PET it falls from +0.27 to +0.11, and at p = 0.113 that residual is not significant. In plain terms, executive function is tied to amyloid mainly through memory. People with more amyloid have worse memory, and worse memory travels with worse executive function.

Read these caveats first

  1. Correlation is not cause. A rho of +0.75 between a blood ratio and a PET scan says they track each other, not that one drives the other.
  2. Significant is not large. With a cohort this size, a Holm-corrected p-value can be small for a rho that is modest. Read the size of rho, not only the star.
  3. Some pairs overlap by construction. Composite scores contain their component tests, and related assays share chemistry. Those pairs will always correlate strongly.
  4. Different pairs, different people. Not every participant had every measure, so the number of people behind each pair varies and is not shown here.

← Biomarkers: the research library

Figures are derived from ADNI data under a Data Use Agreement. Only aggregate statistics are published; no individual participant records are shown.

The Alzheimer's Disease Neuroimaging Initiative (ADNI) is funded by the National Institute on Aging and contributions. This page is not endorsed by ADNI or the National Institute on Aging.