Decreased myelin lipids in Alzheimer's disease and vascular dementia.

The lipid composition of white matter and myelin from the semioval centre was studied in autopsy material from cases with Alzheimer's disease (AD) (n = 11), vascular dementia (VD) (n = 7), and age-matched controls (n = 11). In AD and VD the white matter content of phospholipids and cholesterol was reduced to 72-76% of the control values (P less than 0.01), the diminution of cerebrosides and sulphatides was more pronounced (55-69%) (P less than 0.001) while the concentration of gangliosides did not change significantly (87-90%). The myelin composition was the same in the 3 groups, suggesting that the white matter involvement is not caused by alteration of the myelin structure. The altered lipid composition in white matter in AD and VD suggests that the myelin sheath is the primary lesion site.