Greater WMH volume at baseline , apolipoprotein E 4 status , and smaller ECV at baseline were associated with an increased risk for aggressive decline ( hazard ratio [ HR ] , 1.23 ; 95 % CI , 1.05-1 .43 ; P = .01 for WMH volume ; HR , 1.49 ; 95 % CI , 1.09-2 .05 ; P = .04 for apolipoprotein E 4 status ; HR , 0.66 ; 95 % CI , 0.55-0 .79 ; P < .001 for ECV ) .