Distribution of amyloid deposits in the cerebral white matter of the Alzheimer's disease brain: relationship to blood vessels.

The relationship between blood vessels and amyloid beta (A beta)-protein deposits in the cortex of the Alzheimer's disease (AD) brain is still controversial. It is difficult to distinguish whether the A beta deposits are associated with blood vessels or neurons because of their widespread and complicated distribution. In this study, we investigated the distribution of A beta deposits in the cerebral white matter of the AD brain as a means of removing the bias of neuronal distribution. An immunohistochemical study of 100 serial sections, after pretreatment with formic acid for 24 h, revealed the presence of A beta deposits in the cerebral white matter of the AD brain. There are various morphological types of plaques containing A beta deposits in the white matter, the same as in the gray matter. While the majority of A beta deposits was of a circumscribed type such as "classic" and "primitive" plaques, "compact" and "diffuse" plaques were also observed in the white matter. The location of the A beta deposits was, for the most part, immediately beneath the gray matter. The distribution of A beta deposits in the white matter was found to correspond to the orientation of the blood vessels. Serial sections also revealed that these A beta deposits were distributed along a single blood vessel. These findings suggest that the deposition of A beta in the cerebral white matter is primarily related to the blood vessels.