In a study published in the Journal of Alzheimer’s Disease, researchers revealed that Alzheimer’s disease is caused by a decline in levels of a protein called amyloid-beta. In the study, they hypothesized that plaques are simply a consequence of the decreased levels of soluble amyloid-beta in the brain. These levels decrease because the normal protein, under situations of biological, metabolic, or infectious stress, transforms into abnormal amyloid plaques.

In the study, the researchers analyzed the levels of amyloid-beta in a subset of patients with mutations that indicate overexpression of amyloid plaques in the brain, which is thought to increase the risk of the likelihood of developing Alzheimer’s disease.

The researchers found that with a baseline level of soluble amyloid-beta in the brain above 270 picograms per milliliter, people can remain cognitively normal regardless of the number of amyloid plaques in their brains. In comparison to the control, they found a similar pattern in patients who were thought to have the highest risk of Alzheimer’s disease.

The findings of the study also revealed that individuals already accumulating plaques in their brains who can generate high levels of soluble amyloid-beta have a lower risk of evolving into dementia. 

(Source: https://theprint.in/health/research-reveals-that-alzheimers-disease-is-caused-by-decline-in-levels-of-amyloid-beta/1155245/ )