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

Abstract

The relationship between blood vessels and amyloid β (Aβ)-protein deposits in the cortex of the Alzheimer’s disease (AD) brain is still controversial. It is difficult to distinguish whether the Aβ deposits are associated with blood vessels or neurons because of their widespread and complicated distribution. In this study, we investigated the distribution of Aβ 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 Aβ deposits in the cerebral white matter of the AD brain. There are various morphological types of plaques containing Aβ deposits in the white matter, the same as in the gray matter. While the majority of Aβ 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 Aβ deposits was, for the most part, immediately beneath the gray matter. The distribution of Aβ deposits in the white matter was found to correspond to the orientation of the blood vessels. Serial sections also revealed that these Aβ deposits were distributed along a single blood vessel. These findings suggest that the deposition of Aβ in the cerebral white matter is primarily related to the blood vessels.