I would not worry about this to much. The process (if it happens) will just be a new part of NHS rationing. Oh your blood test shows early Dementia. Pity as now you can join the waiting list for treatment. Unfortunately it is rather long and the outcomes are somewhat variable.
Sorry to be so negative but in my less than a decade of close up experience with Dementia I have seen several.
1) This is potentially a game changer.
2) Within a few years this will revolutionise……
3) NHS will not be able to fund said game changers.
Truth is any way those caring for their loved ones at present will see no immediate change. I pray for an effective treatment, that is soon and affordable. Todate my prayers go unanswered.