Objective: Myelin disruption is an important feature of Alzheimer’s disease (AD) that contributes to impairment
of neuronal circuitry and cognition. In this study we characterize myelin degradation in the brains of patients with
Alzheimer’s disease compared with normal aged controls. Methods: Myelin from patients with AD (n=13) was compared
to matched controls (n=6). Myelin degradation was examined by immunohistochemistry in frontal white matter (WM) for
intact myelin basic protein (MBP), degraded MBP, the presence of myelin lipid and for PAS staining. The relationship of
myelin degradation and axonal injury was also assessed. Results: Brains from patients with AD had significant loss of intact
MBP, and an increase in degraded MBP in periventricular WM adjacent to a denuded ependymal layer. In regions of
myelin degradation, vesicles were identified that stained positive for degraded MBP, myelin lipid, and neurofilament but
not for intact MBP. Most vesicles stained for PAS, a corpora amylacea marker. The vesicles were significantly more
abundant in the periventricular WM of AD patients compared to controls (44.5±11.0 versus 1.7±1.1, p=0.02). Conclusion:
In AD patients degraded MBP is associated in part with vesicles particularly in periventricular WM that is adjacent to areas
of ependymal injury.
Keywords: Alzheimer’s, corpora amylacea, ependyma, myelin basic protein, myelin degradation.
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