These come along pretty regularly and are announced, and re-announced, with great fanfares.
The BBC have run with three of them, as main news headlines, in about a week. First there was the 'new' blood test (which has certainly been mentioned before). Here's an interesting take on it:
This morning the main headline on the Breakfast Programme mentioned two tests, one which would involves cells from the eyelids and one that would test sense of smell. There doesn't seem to be a current online link but a Google search suggests that both have been mentioned by the BBC before.
Of course, the 'small print' always tells you that the tests won't be ready for general use for years, if at all.
And it's sadly also the case that there is no cure for Alzheimer's - existing treatments, at best, help with some symptoms but cannot slow down the progression of the disease. Between 2002 and 2012 99.6% of trials of drugs aimed at preventing, curing or improving the symptoms of Alzheimer's failed or were discontinued. (BBC website article)
So these really aren't breakthroughs in any meaningful sense. Unless you regard thousands of people knowing they are destined to develop a terminal disease as a breakthrough.