Table 2 Proportion of variation of CSF t-tau biomarker levels explained by biomarkers of synaptic degeneration and neurodegeneration

From: CSF total tau as a proxy of synaptic degeneration

Model

pR2

pR2 (%)

R2

ΔpR2

AIC

Cognitively unimpaired

Full

-

-

0.90

-

154a,b

Neurodegeneration

0.12 ± 0.05

15.0%

0.26

0.52

518b

Synapse degeneration

0.86 ± 0.02

95.3%

0.78

−0.52

179

Cognitively impaired

Full

-

-

0.82

-

146a,b

Neurodegeneration

0.17 ± 0.07

23.6%

0.29

0.48

258b

Synapse degeneration

0.74 ± 0.04

90.3%

0.77

−0.48

163

  1. Proportion of variation of CSF t-tau levels explained by neurodegeneration (HCV and CSF NfL combined) and synaptic degeneration (Ng and SNAP25 combined) were estimated using partial R2 (pR2) from multivariable linear regression models adjusted for age, sex and cohort, only for individuals with complete data for all five biomarkers, in cognitively unimpaired (n = 188) and impaired (n = 84) groups. pR2 values are reported as mean ± s.d. obtained by bootstrapping (n = 1000 iterations). Percentual pR2 was calculated as the pR2 of each model divided by the total R2 of the model (100* pR2/R2). The percentage of pR2 does not sum to 100% due to shared variability. pR2 models were calculated based on all variables (full model: t-tau ~HCV + NfL + Ng + SNAP25); only biomarkers of neurodegeneration (synaptic degeneration model: t-tau ~HCV + NfL), or only biomarkers of synaptic degeneration (neurodegeneration model: t-tau ~Ng + SNAP25). ΔpR2 indicates the difference between neurodegeneration and synaptic degeneration pR2 values. AIC values were calculated for models assessing t-tau levels associated with biomarkers of neurodegeneration and synaptic degeneration.
  2. AIC Akaike information criterion. CSF cerebrospinal fluid. t-tau Total-tau. HCV hippocampal volume (HCV). NfL neurofilament light chain protein. Ng Neurogranin. SNAP25 synaptosomal-associated protein 25. Source data are provided as a Source Data file.
  3. aAIC > 15 compared with neurodegeneration.
  4. bAIC > 15 compared with synaptic degeneration.
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