Does mutism from a stroke in front lobe dementia at 83 yrs old indicate late stage and if so how long is this stage likely to last?

See below:: Frontal lobe dementia, usually means gradually progressive disease, affecting the frontal lobes, and over years and in the later stages of the disease, mutism may result often with other symptoms (lack of drive, disinhibition or bizarre behavior, problems with planning and judgement). A stroke may cause similar symptoms, but comes on rapidly. Recovery in much older patients is often poor or slow.