Role of amyloid from a multiple sclerosis perspective: a literature review

The traditional concept of multiple sclerosis (MS), that it is primarily a white matter inflammatory disease, has changed a great deal. Thanks to the recent development witnessed in MS research, a whole new idea has emerged that MS is a neurodegenerative disease, and neurodegeneration occurs rather earlier in the pathological process. This has also led to the foundation of the hypothesis that two fundamentally different diseases, Alzheimer's disease (AD) and MS, may share a common mechanism of neurodegeneration. Conventionally, amyloid is thought to be a consequence of protein misfolding and aggregation and is most notorious for its association with debilitating and chronic human diseases. Amyloid is implicated to be related with the deterioration and progression of AD. The finding of amyloid precursor protein expression in axons around the plaque in MS, as well as the correlation of amyloid-β (Aβ) with different stages of MS, has clearly indicated that amyloid plays some kind of key role in MS disease pathogenesis. Excitingly, a paradoxical phenomenon of Aβ has also been observed in several studies recently. It has been shown that amyloid might actually be helping in ameliorating the inflammatory effect in diseases like AD and MS. Amyloid imaging allows earlier diagnosis of MS by taking advantage of the relation of amyloid with MS. This will have a big impact on patient diagnosis and management. In this review I have included the findings of research studies dating from several years back to the most recent ones. Through this review I have tried to show the critical role of amyloid in MS and the importance of investigating through PET imaging.