What Are The Early Signs Of Dementia?

My wife was never fully diagnosed with Alzheimer s but the consensus appeared to be the cause of her declining memory problems. This started about 5 years ago with 2 strokes affecting her left brain. There appeared to be little difference between left and right body strength and did not seem to suffer and typical body reactions. She quickly learned how to walk, eat, dress but it took much longer to recover memory and speak. Two years ago I retired to take care of her full time. In the last few weeks, she has had very rapid physical decline. She used to dance with me almost every day, could walk unassisted and mostly could dress, go to the bathroom by herself, brush her own teeth and feed herself. Now she cannot do anything at all without assistance. Her joints are very stiff and she cannot stand, walk or get in and out of bed by herself. She is also almost constantly shaking her hands and arms, sometimes quite violently. Is this a clear symptom or dementia with Lewy? Is there any correlation to stage 7 Alzheimer s. Beginning, middle of late stage 7?