Restless & agitated more than a month.

Father 77 years old is recently diagnosed with dementia ( when we had to admit him because of sudden agitated and restless behaviour) he had memory disturbances, talking repeated topics, forgetting recent events etc for more than 4 years but we suspected it to me old age. But after his diagnosis last month, he had always stayed restless, talking constantly that may not make sense, searching for something but won't know what is it when asked for, always fearing about someone may harm or steal etc. He is on medication to improve his cognition, sleeping dose in night and meds to control his restlessness but the actual behaviour hasn't improved. This sudden deterioration is part of dementia or could it be something else.