Neuropsychological impairment correlates with hypoperfusion and hypometabolism but not with severity of white matter lesions on MRI in patients with cerebral microangiopathy

Background and Purpose-Cerebral microangiopathy, indicated on MRI by lacuna r infarctions (LI) and deep white matter lesions (DWML), is said to lead to vascular dementia. Methods-Fifty-seven patients with proven cerebral microangiopathy were asse ssed for changes in regional cerebral blood flow (rCBF) and glucose metabol ism (rMRGlu) and compared with 19 age-matched controls. The findings were c orrelated with results of extensive neuropsychological testing, as well as with MRI findings. A special head holder ensured reproducibility of positio ning during rCBF (single-photon emission CT [SPECT]), rMRGlu (positron emis sion tomography [PET]), and MR imaging. White matter and cortex were quanti fied with regions of interest defined on MRI and superimposed to correspond ing PET/SPECT slices. LI and DWML were graded by number and extent. Results-Even with severe DWML and multiple LI, rCBF and rMRGlu values were not reduced. ANOVAs identified brain atrophy and neuropsychological deficit s as the main determinants for reduced rCBF and rMRGlu values in both corte x and white matter. Neuropsychological deficits correlated well with decrea sed rCBF and rMRGlu, whereas MRI patterns such as LI and DWML did not. Fact or analysis revealed no correlation of LI and DWML with rCBF, rMRGlu, atrop hy, and neuropsychological deficits, showing instead positive correlations between rCBF, rMRGlu, and neuropsychological performance and negative corre lations of the latter 3 with brain atrophy. Conclusions-From these data, we conclude that LI and DWML are epiphenomena that may morphologically characterize cerebral microangiopathy but do not i n themselves indicate cognitive impairment. Dementia or neuropsychological deficits. by contrast, are reflected exclusively by functional imaging para meters (rCBF, rMRGlu) and cerebral atrophy.