Dementia rates in the UK falling????

I was on holiday when this story broke.  If you google it you'll find it's reported in several places.

I haven't seen any comments on it  -  very odd, as we have been bombarded for several years with the opposite message.

I'd be interested in any views. I notice that it seems to concern dementias in the elderly exclusively. Some people believe there has been a dramatic increase in the incidence of young onset dementias, though I have not seen firm evidence on this.