This is the Guardian. Alzheimer's. It accounts for nearly two-thirds of the 55 million people living with dementia worldwide,

and it's the leading cause of death in the UK.

It costs us 25 billion pounds a year and that's expected to double by 2050. Until now the prognosis has been bleak with diagnosed patients facing a slow harrowing decline.

But in November, research has announced a therapy that might see the dawn of a new era for

Alzheimer's treatment. So just how effective is this new drug and could a cure

for Alzheimer's be on the horizon.

For the Guardian, I'm Ian Sample and this is Science Weekly. Professor Nick Fox,

Fox, you're the director of the Demential Research Center at UCL,

and you've been looking closely at this new research into Alzheimer's.

How exactly does Alzheimer's work? Well, Alzheimer's is the

commonest cause of dementia and it's a neurodegenerative disease. By that I mean

neurons degenerate over time,

synapses are lost and there's those connections between nerve cells break down.

All the things that make us a thinking human gradually break down with memory typically being the first change.

The driving cause in terms of biology, we now understand that there is a particular abnormal protein called amyloid that is deposited in the brain and the brain can't clear it out.

Another protein called tau builds up in tangles of dead or dying

neurons and then connections are lost and that then after a number of years has toxic effects on our brain cells. So there is a long

period of amyloid buildup followed by the accumulation of tau, followed by destruction of neurons, followed

by symptoms that all occur prior to diagnosis.

Probably a 20 year window.

And how common is Alzheimer's?

What sort of impact is it having?

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