THE EFFECT OF WHITE-MATTER LOW ATTENUATION ON COGNITIVE PERFORMANCE IN DEMENTIA OF THE ALZHEIMER-TYPE

The effect of leukoaraiosis or white matter low attenuation (WMLA) on cognitive function is not fully understood. We compared the neuropsych ological performance of 37 Alzheimer's disease patients with WMLA on C T brain scans with a similar group of 31 Alzheimer's disease patients with no evidence of white matter lesions. Patients with WMLA performed significantly worse on tests of visuospatial function (Cube Analysis test, p = 0.004), and cognitive speed (Kenrick Digit Copying test, p = 0.05) compared to those with no visible white matter lesions. Patient s with widespread WMLA performed generally worse in tests of cognitive function than those with frontal or a mixture of frontal and occipita l WMLA. This was most significant in the areas of attention (forward d igit span, p = 0.003), visual recognition (p = 0.004), and cognitive s peed (p = 0.03). There is an association between impaired cognitive pe rformance and the presence of WMLA in Alzheimer's disease patients, wi th WMLA probably contributing to the cognitive impairment. This is mos t evident in patients with widespread white matter lesions.