Table 2.

Association between Blood-Brain Barrier Disruption and White Matter DTI Metrics.

Model with Linear BBBD term	Beta Coefficient		R2 for model	p-value
Free Water	0.35 [0.33 to 0.37]		0.46	<0.001
FA corrected	0.34 [0.31 to 0.36]		0.40	<0.001
MD corrected	0.34 [0.31 to 0.37]		0.40	<0.001
Model with Quadratic BBBD term	Beta, Linear Term	Beta, Quadratic Term	R2 for model	p-value
Free Water	0.57 [0.48 to 0.66]	−0.040 [-0.056 to −0.025]	0.47	<0.001*
FA corrected	0.73 [0.60 to 0.86]	−0.072 [-0.095 to −0.050]	0.41	<0.001*
MD corrected	0.41 [0.28 to 0.53]	−0.012 [-0.017 to 0.023]	0.40	0.28

Each DTI metric was converted to a Z-score to facilitate comparison across metrics. Separate mixed effects linear regression models were used to predict each mean DTI Z-score across all white matter. All models include covariates for age, sex, race, and MRI site. For each metric, a linear term and a quadratic term for BBBD were tested, and regression coefficients and [95 % confidence intervals] are shown. *Indicates better fit for quadratic over linear model using Wald test with p < 0.001. BBBD: Blood-brain Barrier Disruption; FA: fractional anisotropy; MD: mean diffusivity; CI: confidence interval; Std: Standardized.