Regional distribution of white matter hyperintensities in vascular dementia, Alzheimer's disease and healthy aging

Background: White matter hyperintensities (WMH) on MRI scans
indicate lesions of the subcortical fiber system. The regional
distribution of WMH may be related to their pathophysiology and
clinical effect in vascular dementia (VaD), Alzheimer's disease
(AD) and healthy aging. Methods: Regional WMH volumes were measured
in MRI scans of 20 VaD patients, 25 AD patients and 22 healthy
elderly subjects using FLAIR sequences and surface reconstructions
from a three-dimensional MRI sequence. Results: The intraclass
correlation coefficient for interrater reliability of WMH volume
measurements ranged between 0.99 in the frontal and 0.72 in the
occipital lobe. For each cerebral lobe, the WMH index, i.e. WMH
volume divided by lobar volume, was highest in VaD and lowest in
healthy controls. Within each group, the WMH index was higher in
frontal and parietal lobes than in occipital and temporal lobes.
Total WMH index and WMH indices in the frontal lobe correlated
significantly with the MMSE score in VaD. Category fluency
correlated with the frontal lobe WMH index in AD, while drawing
performance correlated with parietal and temporal lobe WMH indices
in VaD. Conclusions: A similar regional distribution of WMH between
the three groups suggests a common (vascular) pathogenic factor
leading to WMH in patients and controls. Our findings underscore
the potential of regional WMH volumetry to determine correlations
between subcortical pathology and cognitive impairment. Copyright
(C) 2004 S. Karger AG, Basel.