When a person has Alzheimer’s disease, it is usually the result of a build-up of two types of lesions – amyloid plaques, and neurofibrillary tangles. Amyloid plaques sit between the neurons and end up as dense clusters of beta-amyloid molecules, a sticky type of protein that clumps together and forms plaques.
Researchers have come up with a non-invasive ultrasound technology that clears the brain of neurotoxic amyloid plaques – structures that are responsible for memory loss and a decline in cognitive function in Alzheimer’s patients.
Neurofibrillary tangles are found inside the neurons of the brain, and they’re caused by defective tau proteins that clump up into a thick, insoluble mass. This causes tiny filaments called microtubules to get all twisted, which disrupts the transportation of essential materials such as nutrients and organelles along them, just like when you twist up the vacuum cleaner tube.
As we don’t have any kind of vaccine or preventative measure for Alzheimer’s – a disease that affects 343,000 people in Australia, and 50 million worldwide – it’s been a race to figure out how best to treat it, starting with how to clear the build-up of defective beta-amyloid and tau proteins from a patient’s brain. Now a team from the Queensland Brain Institute (QBI) at the University of Queensland have come up with a pretty promising solution for removing the former.
Publishing in Science Translational Medicine, the team describes the technique as using a particular type of ultrasound called a focused therapeutic ultrasound, which non-invasively beams sound waves into the brain tissue. By oscillating super-fast, these sound waves are able to gently open up the blood-brain barrier, which is a layer that protects the brain against bacteria, and stimulate the brain’s microglial cells to activate. Microglial cells are basically waste-removal cells, so they’re able to clear out the toxic beta-amyloid clumps that are responsible for the worst symptoms of Alzheimer’s.
The team reports fully restoring the memory function of 75 percent of the mice they tested it on, with zero damage to the surrounding brain tissue. They found that the treated mice displayed improved performance in three memory tasks – a maze, a test to get them to recognise new objects, and one to get them to remember the places they should avoid.
“We’re extremely excited by this innovation of treating Alzheimer’s without using drug therapeutics,” one of the team, Jürgen Götz, said in a press release. “The word ‘breakthrough’ is often misused, but in this case I think this really does fundamentally change our understanding of how to treat this disease, and I foresee a great future for this approach.”
The team says they’re planning on starting trials with higher animal models, such as sheep, and hope to get their human trials underway soon.
You can hear an ABC radio interview with the team here.