The decline with dementia (my mother has it) is not steady,. Sometimes the patient can remain very stable for quite a length of time, and other times can have a sudden decline over a relatively short period. Biden has declined notably in the last few months.Each public speaking engagement he gets worse. NFW will he last until the election.
Evidently he gets very agitated and angry - a typical symptom of dementia patents.
I will tell you that my mother is now in assisted living, and she is in better mental shape than the president. Scary.