TABLE 5.

Summary of the linear regression analysis in exploring clinical predictors for apathy severity.

Model		Unstandardized coefficients		Standardized coefficients			Summary of model
		B	Standard Error	Beta (b*)	t	p	R 2	Adjusted R2	△R2	△F	P-value of △F
1	Constant	26.358	1.780		14.811	< 0.001	0.425	0.417	0.425	56.867	< 0.001
	CDR_SOB	2.641	0.350	0.652	7.541	< 0.001
2	Constant	24.469	1.851		13.217	< 0.001	0.475	0.461	0.050	7.192	0.009
	CDR_SOB	2.322	0.357	0.573	6.499	< 0.001
	WMH volume	0.556	0.207	0.236	2.682	0.009
3	Constant	22.098	2.026		10.906	< 0.001	0.515	0.496	0.040	6.244	0.015
	CDR_SOB	2.333	0.346	0.576	6.752	< 0.001
	WMH volume	0.572	0.201	0.243	2.851	0.006
	BDI	0.325	0.130	0.201	2.499	0.015

The independent variables entered into the stepwise linear regression model included age, education, gender, the Beck Anxiety Inventory, the Beck Depression Inventory (BDI), Clinical Dementia Rating sum of box (CDR_SOB), and white matter hyperintensities (WMH) volume. None of the first-order correlations were above 0.70 (or below -0.70), therefore generally excluding the issue of multicollinearity. Variables including age, education, gender, and the Beck Anxiety Inventory were finally removed.