1. SIVD patients divided into VaD and VCIND group and normal elderly controls matched in age and gender would be recruited. The quantitative analysis of N-acetylaspartate (NAA), myoinositol (mI), Choline (Cho) and Creatine (Cr) resonance signals in region of interests located in thalamus and paraventricular white matter region would be measured. Ratios of NAA/ Cr, mI/ Cr and Cho/ Cr would be calculated in three groups.