Background and objectives: Subcortical vascular dementia (VaD) is a relatively homogeneous subtype of VaD, but the mechanisms of cognitive dysfunction of subcortical VaD are not fully understood. This study investigates the changes of cerebral blood flow (CBF) in patients with subcortical VaD and the contribution of the white matter hyperintensity (WMHI) and clinical severity to CBF changes.
Methods: 99mTc-ethyl cysteinate dimer single photon emission computed tomography (SPECT) was performed to measure the regional CBF and statistical parametric mapping SPM99 software was applied to automated and objective analysis of the SPECT image data. Twenty-three patients (12 male, 11 female) with mild to moderate dementia who met both the criteria of the DSM-IV and probable and possible NINDS-AIREN for VaD and had subcortical white matter changes and lacunar infarctions in brain MRI were evaluated against 17 normal control subjects (7 male, 10 female). The severity of the WMHI was measured by the semi-quantitative scale method proposed by Mäntyla. The Clinical Dementia Rating scale measured the severity of dementia.
Results: SPM analysis of the SPECT image reveals significantly reduced regional CBF in the right thalamus, left caudate nucleus, cingulate, bilateral superior temporal, and left ventral subcallosal gyri in subcortical VaD patients compared to the normal controls (corrected P<0.001). Of four WMHIs, only the deep WMHI was associated with the small CBF reduction in the left superior temporal gyrus (uncorrected P<0.01). The reduction of the CBF according to the severity of dementia was noted in the anterior and posterior association areas (uncorrected P<0.01).
Conclusions: Our study suggests that cognitive dysfunction of subcortical VaD may be related to the reduction of the CBF in the brain areas mentioned, which are probably not associated with the severity of periventricular WMHI and dementia.