(1) White matter density 5mm FWHM filtering

Sample variance of controls at x y z = 0.00016
Sample variance of melancholic = 0.0015

mean sample variance of mel = 0.0049
mean sample variance of control = 0.0046

var difference is between -0.066 to 0.075.
mean var diffence is 0.000253. However in medial PFC
region x,y,z=(43,26,15), there is about 860% more variabilites in the melancolic patients.

There are about 4% more white matters in medial PFC region (P-value = 0.00038, t=3.7381).

(2) Gray matter density with 5mm FWHM filtering
 
sample variance of contorls = 0.00036
sample variance of melancholic = 0.0012

200% sample variance difference indicates that the melancholic patients has more structural
variabilities compared to controls.

Mean sample variance difference = 0.00055 the difference is statistically significant at 0.00001%  level.
So obviously the variances of controls and melancholic patients are different but we still need to
use
t=-3.5829
gray matter mean for controls = 0.9610
gray matter mean for melancholic depression = 0.9231
gray matter mean difference = 0.0379
4% more gray matter with P-value = 0.00057

(3) White matter density 10mm FWHM