Scientists say a new drug could bring hope to Alzheimer's sufferers and their families.
A small study has found the drug, aducanumab, can remove the unwanted protein that builds up on the brains of people with early stages of the disease. But it comes with a word of caution.
Around the world, one person is diagnosed with dementia every four seconds. In New Zealand there are around 60,000 people with the disease, and that's expected to almost triple over the next 35 years, so scientists are desperately trying to find a cure.
Scientists believe that Alzheimer's could be caused by a build-up of protein which destroys the brain cells.
Aducanumab appears to remove toxic proteins in patients with early-stage disease.
In the study of 165 people, half received a year's worth of treatment - significantly reducing the amount of amyloid beta protein in the brain - while the other half got a placebo, and showed little improvement, if any.
It was a small trial and the results don't suggest aducanumab is a cure, but scientists believe it could be a major step forward.
"We don't have any drugs that can slow down or stop those diseases, so if this drug works it will be the first what's called 'disease modifying drug' to come forward, so something that can actually slow down the disease," says Dr David Reynolds, Chief Scientific Officer, Alzheimer's Research UK.
Brenda Whittle is taking part in an Alzheimer's trial and her husband Stephen says she agreed to take part almost as soon as she was diagnosed.
"Brenda said even if it may be too late for me, and I hope it's not, we will certainly be helping other people."
The trial mainly tested the safety of the drug; whether or not it works to improve memory will have to wait until two larger phase three trials are completed in 2020.
Scientists in New Zealand are cautiously optimistic.
"The concept of having a drug that clears amyloid is not new," says Dr Maurice Curtis from the University of Auckland's Centre for Brain Research.
"This drug seems to be safe, but does clearing the protein improve memory? So far that does not seem to be the case."
But he supports the larger study going ahead, as he says there isn't anything better.
Even if they are successful, early diagnosis will be key, to enable treatment to start before the brain becomes irreversibly damaged.