I have given this a great deal of thought. both my parents and father-in-law died in the grip of dementia and my mother-in-law is on the verge of needing a great deal of care due to dementia.
on balance, I think I want to know. once its diagnosed, there are potential problems with finance, property etc. if power of attorney hasn't been sought before the diagnosis, then it's too late. id want to put my affairs in order and do what needs to be done, sorting out bank accounts, thinking about end of life care, cheery things like that
the problem with dementia is that it creeps up on you and in the early days minor issues can be dismissed. before you know it, its too late.