Alzheimer’s Disease and the Clearance of Amyloid Beta Protein

[This article first appeared in: Dementia Newsletter RWHT Volume 1 Issue 6 January 2011].


Amyloid beta is normally released in the brain and cleared, but in Alzheimer’s disease the protein accumulates in the brain and causes cell death. The brains of 12 people with mild Alzheimer’s disease and 12 people without dementia were compared to see how amyloid beta protein is produced and cleared. People with Alzheimer’s disease were found to clear amyloid beta protein 30% slower than unaffected individuals. This suggests that slower clearance of the protein, rather than its over-production, causes the accumulation of amyloid beta protein in Alzheimer’s disease. Given a 30% slower rate of amyloid beta clearance, it is estimated that amyloid beta in the brain accumulates over approximately 10 years in Alzheimer’s disease.

Late-onset Alzheimer’s disease (which affects elderly people rather than the rarer early onset form that may affect people in their fifties) “is associated with a 30% impairment in the clearance of Aβ40 and Aβ42, indicating that amyloid beta clearance mechanisms may be critically important in the development of Alzheimer’s disease”.

Critics say this was only a small study and it could be that impaired amyloid beta clearance is a consequence – instead of a cause – of Alzheimer’s disease. To establish whether this is a cause rather than an effect, the researchers would have to follow a larger group of subjects over time from before they had Alzheimer’s disease. This research does at least highlight the importance of amyloid beta clearance in Alzheimer’s disease and inspire further research.

Full Text Link (a)


Slow protein clearance ‘clue to Alzheimer’s’. BBC News, Health, December 10th 2010.

Full Text Link (b)


Mawuenyega, KG. Sigurdson, W. [and] Ovod, V. [et al]. Decreased Clearance of CNS {beta}-Amyloid in Alzheimer’s Disease. Science, December 9th 2010. [Epub ahead of print].

About Dementia and Elderly Care News

Dementia and Elderly Care News. Wolverhampton Medical Institute: WMI. (jh)
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