Explainer | Unravelling 2 Alzheimer’s markers: what are amyloid plaques and tau tangles, how do they form and what do they do to the brain?
- People with Alzheimer’s disease have amyloid plaques and tau tangles in their brains. These are caused by build-ups of proteins that block electrical messages
- Techniques developed recently have shown these protein build-ups in action, changing from liquid to solid, offering new information about the process
Amyloid plaques and tau tangles are telltale signs of Alzheimer’s disease – you hear the phrase all the time in connection with dementia, but what are they?
Neurologist Dr Andrew Lees, a professor of neurology at the National Hospital in London and University College London and an expert on neurodegenerative diseases, explains the way plaques and tangles work.
The plaques consist of dense, insoluble clumps in the spaces between the nerve cells, or neurons, in the brain. They prevent the brain’s messages from getting through effectively or – eventually – at all. They are composed of beta-amyloid, a protein.
Tangles are the result of a build-up of tau protein inside neurons. In a healthy brain, tau binds with the neurons’ internal structures, microtubules, which help disperse nutrients throughout the neuron.
As Alzheimer’s progresses, the tau sticks to other tau proteins, forming long protein threads of tau inside the neurons – tangles – and ultimately, these interfere with the neuron’s ability to function.
