Always five years or multiples thereof.

I have just read a piece suggesting that a dramatic new treatment is 'just five years away' for Alzheimers.

Why are these 'miracle cures' always described thus?

Why are they never 'eighteen months away', for example?

Why do we not get press coverage when they actually arrive?

I am afraid that tabloid sensationalism must build an awful lot of false hope for a great many people.