Did you take him to see the psychiatrist or neurologist for any diagnosis? It would help to know what type of dementia is this. Christine mentioned before that the diagnosis helps.  It can clarify the disease and you can get him treatments accordingly. I am not sure what you mean by not understanding the words. It may not be the words that he does not know, but the context or situations that he does not understand. e.g., my father-in-law is in stage 6 with Alzheimer's and he is 88. Now he can no longer remember his career as a professor and he can not understand his finances as usual, and he does not know he lives in his own house. So if we talk to him and say that this is his house or that his office was at UIC and etc, he would be confused and get lost. He would then ask many questions because he does not understand. Also he can no longer understand social conversations anymore. His close friend said he can no longer carry conversations anymore. But he can still use fine words. He has trouble expressing his true feelings or finding the right words to say. But if the person talks to him carefully just to please my FIL, then the conversation could carry on in the sense that it only pleases him or goes his way. It is not 2-way street anymore. He does not understand why he cannot drive and work. He is retired but he keeps thinking he needs to work for money. I think you should ask his family doctor about what to do. If he cannot refer him to a neurologist or psychiatrist to diagnose him with a type of dementia, at least the family doctor can give him some drugs for dementia or Alzheimer's. These drugs help to delay the symptoms for 6 months or more.   Take care, Nina