Does Myelin Play the Leading Role in AlzheimerâÂÂs Disease Pathology?

Although Alzheimer’s disease (AD) has been mainly considered as a grey matter disorder, there is emerging evidence that myelin impairment may play an important role in AD pathology. These data come from animal neuropathological studies, but also from human pathological, biochemical and brain MRI studies. Classical neuropathological changes in AD such as the accumulation of aggregated As 42 and the presence of neurofibrillary tangles are responsible for neuronall loss, but they may also induce death of oligodendrocytes and myelin impairment. Accelerated deposition of As in brains of AD patients induces damage to oligodendrocytes and results in impaired myelin production. What is more interesting, there is also evidence that myelin pathology may precede As and tau pathologies in AD. Recent studies suggest that As and tau proteins may be by-products of myelin repair in AD, instead of being the primary underlying cause of dementia. This seems possible, considering the fact that attempts to control clinical symtomps of AD by removing As from the human brain have been unsuccesful. In this article, current knowledge on the place of myelin in AD pathology and its interactions with As and tau pathology is reviewed.