Table 2.

Univariate Analyses and Linear Regression Models for WMH and DTI FA and MD

Outcome variable	Univariate analyses			Multivariate linear regression
Outcome variable	Predictor variable	Spearman P or directionality	P value	Unstandardized β (95% CI)	P value	Model R²_adj; P value
Normalized WMH volume	White matter CBF	NS	0.432			0.697; <0.001
	Watershed CBF	NS	0.205
	White matter OEF ratio^*	0.740	<0.001
	Watershed OEF ratio^*	0.646	<0.001	0.207 (0.119 to 0.295)	<0.001
	Age^*	0.654	<0.001
	Hypertension^*	Higher	<0.0001	0.018 (0.010 to 0.025)	<0.001
	Diabetes^*	Higher	0.001
	Hyperlipidemia^*	Higher	0.072
	Race	NS	0.558
	Sex	NS	0.334
DTI FA	White matter CBF	NS	0.776			0.303; <0.001
	Watershed CBF	NS	0.362
	White matter OEF ratio^*	−0.431	0.004
	Watershed OEF ratio^*	−0.455	0.002	−0.243 (−0.445 to −0.041)	0.020
	Age	NS	0.332
	Hypertension^*	Lower	0.002
	Diabetes^*	Lower	0.005	−0.022 (−0.043 to −0.001)	0.041
	Hyperlipidemia	NS	0.459
	Race^*	NS, Black race lower	0.027
	Sex^*	Male lower	0.044
DTI MD	White matter CBF	NS	0.227			0.423; <0.001
	Watershed CBF^*	−0.264	0.087
	White matter OEF ratio^*	0.504	0.001
	Watershed OEF ratio^*	0.496	0.001	0.326 (0.041–0.611)	0.026
	Age^*	0.256	0.101
	Hypertension^*	Higher	<0.001	0.037 (0.014–0.061)	0.002
	Diabetes^*	Higher	0.020
	Hyperlipidemia	NS	0.440
	Race	NS	0.342
	Sex^*	Male higher	0.044

References for the categorical variables: absence of hypertension, diabetes, hyperlipidemia, race self-identified White, and sex self-identified female. CBF indicates cerebral blood flow; DTI, diffusion tensor imaging; FA, fractional anisotropy; MD, mean diffusivity; NS, not significant; OEF, oxygen extraction fraction; and WMH, white matter hyperintensities.

P<0.20 threshold for entry into the linear regression.