hello
@jane camp
a warm welcome to DTP
yes, many here will recognise exactly what you describe ...we call it 'host mode' as it seems the person can pull together all their energy to seem their old self for a visitor for some time, pretty much as most of us 'put on the style' for visitors ... yet, as soon as the visit is over, they are exhausted with the effort and simply cannot keep up the appearance
it can be very frustrating as family and even medics can be fooled by this ability to seem unaffected by dementia
they say animals rarely show distress or pain to their fellows as then they will be seen to be weak and the weak in groups get the least resources and fall to prey, so 'putting on a show' is a survival technique