Table 3. Multiple regression models for corpus callosum region IV FA in each diagnostic group.

Variables		CN (n=107)	MCI (n=77)	AD (n=47)
GM IV vol.	beta	0.283	0.260	0.328
	ΔR2	0.074	0.059	0.129
	P-value	0.005	0.036	0.017
Posterior WMH vol.	beta	0.053	0.109	-0.406
	ΔR2	0.002	0.009	0.156
	P-value	0.621	0.416	0.008
Age	beta	-0.044	-0.121	0.020
	ΔR2	0.002	0.010	<0.001
	P-value	0.677	0.400	0.889
Overall model	R2	0.081	0.095	0.271
	P-value	0.033	0.064	0.004

FA = fractional anisotropy; CN = cognitively normal; MCI = mild cognitive impairment; AD = Alzheimer's disease; GM = gray matter; WMH = white matter hyperintensities;