What Causes Dementia And Twitching Sensation In The Hands And Legs?

85 year old mother, insulin dependent diabetic for 35+ years, has CHS, 5 foot 2 and weighs 220 pounds, has a pacemaker. My mother has just been diagnosed with dementia. Sometimes as my mother has a blank look on her face when someone asks her a question. She has been twitching her hands recently and sometimes her legs. Had an EEG last Wednesday and all was fine. She had a UTI early last week but it is clear today. Today both her knees gave out on her on the way to the bathroom. Any ideas on what could be wrong with my mother??