Early cognitive decline may be due to collection of amyloid in blood vessels

Alzheimer’s disease, primarily a disease of the elderly people, is a neurodegenerative disease characterized by progressive cognitive decline. It is well known that deposition of amyloid β-protein (Aβ) in the brain, in the form of amyloid plaques around the neuronal cells, is responsible for this cognitive impairment. However, in a new study published in the recent online issue of the Journal of Alzheimer’s Disease, researchers from Stony Brook University, led by William Van Nostrand, a Professor in the Department of Neurosurgery, have found that accumulation of amyloid β-protein in the cerebral blood vessels may be the main reason behind the early cognitive decline.

For their study, the researchers compared the impact of amyloid deposition in two different transgenic mouse strains- Tg-5xFAD and Tg-SwDI. Although both the strains showed accumulation of amyloid β-protein in the brain, in Tg-5xFAD the deposition of amyloid was parenchymal whereas in Tg-SwDI, the amyloid deposition was more in the micro vascular compartment. Cohorts of both the strains of mice were tested at 3 months and at 6 months of age, and the relationship between the amount of amyloid deposition and spatial working memory performance were compared.

The researchers observed that at three months of age, the Tg-SwDI mice with cerebral micro vascular amyloid deposition showed a cognitive impairment while the Tg-5xFAD mice were mentally alert. However, at the age of six months, both the strains showed comparative cognitive decline. This is because by this time, the amyloid β-protein deposition in the brain of the Tg-5xFAD mice was extremely high. This finding has led the researchers to believe that early-onset cerebral micro vascular amyloid deposition precedes high parenchymal levels of Aβ in Alzheimer’s disease. This amyloid deposition in the cerebral vessels may be an important factor in the development of early cognitive decline.

The researchers have opined that this finding should be corroborated with further studies. If it is established that amyloid deposition in the cerebral vessels is indeed the reason behind the development of early cognitive deficits, this may open a new way of dealing with Alzheimer’s disease. Targeting the amyloid build-up in the blood vessels of the brain may become a treatment strategy in the early stages of Alzheimer’s disease.

Editor: Dr. Bimal Rajalingam MBBS DNB 
Thursday, November 28, 2013
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