Alzheimer’s disease has long been assumed to originate in the brain, but new research reveals it might actually be triggered by breakdowns elsewhere in the body, before travelling to its final destination.
Amyloid-beta are the disruptive proteins which cause a ‘plaque’ to build up in the brain and impair functionality, but a new study has found that the proteins can actually move around the body like cancer.
Professor Dr. Weihong Song, who worked on the study, said: “Alzheimer’s disease is clearly a disease of the brain, but we need to pay attention to the whole body to understand where it comes from, and how to stop it.”
The team from the University of British Columbia were inspired to look at the earlier origins of the disease, which currently has no cure, because if their suspicions were correct then drug therapies could target other easier-to-reach organs than the brain.
For example, targeting the kidney or liver ridding it of a toxic protein before it reaches the brain.
In order to test their theory, they used a technique called parabiosis where they surgically attach two mice to each other so they are sharing the same blood supply.
Taking one normal mouse (mice cannot naturally get Alzheimer’s disease) and one mouse that had been modified to carry the human amyloid-beta gene, they were merged into one for a period of a year.
After this time, the scientists tested the previously healthy mouse and found it had ‘contracted’ Alzheimer’s’ disease from the other mouse because the amyloid-beta have travelled in the bloodstream to the undamaged brain.
Not only that but the mice developed the twisted ‘tangle’ protein strands that form inside brain cells, disrupting their function and other signs of Alzheimer’s-like damage including brain cell degeneration, inflammation and microbleeds.
In addition, the ability to transmit electrical signals involved in learning and memory was impaired, even in mice that had been joined for just four months.
This could also explain why Alzheimer’s occurs with age, as the blood-brain barrier weakens and the amyloid-beta can move more freely.
Song said: “The blood-brain barrier weakens as we age. That might allow more amyloid beta to infiltrate the brain, supplementing what is produced by the brain itself and accelerating the deterioration.”
Alzheimer’s disease is the most common type of dementia, a progressive and irreversible neurological disease which affects multiple brain functions and affects an estimated 850,000 people in the UK.