Alzheimer's disease

is such a strange thing.
Our friends K and B came for lunch yesterday. K is one of the Senior Cat's oldest friends. Once K was a highly articulate man, quick to make a pun and recognise one. He had a prodigious memory and never needed prompting on stage in the theatrical productions he loved.
All that changed some years ago. He seemed to occasionally forget things or get distracted. Then he couldn't remember his lines in a production and stopped participating in plays. Other little things happened. 
At first they put it down to "old age" but it gradually became obvious that the problem was more than that. Tasks would not be completed. K would go to do something at the other end of the house and "forget" on the way there what it was he intended to do. He went to check the water pump which supplies the power to the small dam on their property - vital water for fire protection - and just stood there not sure what to do.
Eventually he was diagnosed with Alzheimer's disease. That was some time ago now. 
He had to stop driving. B now does the driving. They need a car because there is no public transport where they live. 
Although the Senior Cat has talked with both K and B on the phone they had not seen one another in over twelve months. The transport issues mean they have to come us  rather than we go to them. It had been months since the Senior Cat had talked to K... without B listening in and talking as well. 
     "K... doesn't seem too bad," the Senior Cat told me.
I wondered. I had talked to B.... and I knew she was worried.
Yesterday I could see why she was worried. On the surface K... still appears almost normal. The casual observer might not think anything was wrong.
But there is. His constructions are sometimes awkward. It is clear he can no longer remember a word and searches for something else.  He couldn't remember the word "dam" - "that water thing at the bottom of the hill". The dam is something he constructed and has carefully maintained for years. He has always seen it as being of vital importance. Other little things came  up. None of them were of any great importance in themselves. It was the cumulative effect on his ability to communicate that was obvious to me. 
     "What do you think?" B... asked me anxiously as we were returning  used plates to the kitchen.
     "I can see it," I told her, "But a lot of people won't yet."
     "Yes, that's what worries me. They don't think there is anything wrong."
I can understand that. 
When they had gone the Senior Cat said to me, "K...doesn't seem too bad but he missed some words."
I agreed and then I said the other thing that I had noticed,
      "And he didn't initiate any of the conversation."
The Senior Cat thought about that for a moment and then said,
      "You're right. I hadn't noticed it but now you mention it... it's as if he has stopped asking questions."
That makes it very serious indeed.