I would think of it as a Venn diagram, where you have two circles overlapping and the overlap would be extraordinary. The symptoms alone don’t usually differentiate rapidly progressive dementia from other dementias. It’s the time course of the presentation of those symptoms.
All the symptoms you see in a slower dementias — Alzheimer’s disease where you have episodic memory loss and later on in the disease you have long-term memory loss, Parkinson’s disease where you have motor dysfunction, frontotemporal dementia where you have a lot of behavior and personality changes, Huntington’s disease where you have abnormal increased movements — all of these things can occur in rapidly progressive dementia, but the time course, the evolution of the onset of these symptoms is faster. That’s usually what would tell somebody, ‘This isn’t a normal dementia. This is rapidly progressive.’
It’s important to know that because like that Venn diagram, there is a similar workup or differential, but there are things that normally you wouldn’t think of for a slow dementia.