Hi just had a quick search for journals at work and Pfizer (the drug company) says that 62% of dogs over 10 will show some sign of CCD (canine cognitive disfunction). Scary!!!
The symptoms are increased aggression and/or irritablility, staring into space, decreased activity, pacing at night or a change in sleep patterns, forgetting family members and learned behaviour, a return to puppyhood with reguards to toilet training, confusion and getting lost in the garden and behind furniture etc, no long paying attention to the owner.
It maybe worthwhile having a word with ur vet if you think he has any of these because I think there is a drug called Selegiline which can be used for it. There are also quite a few websites on it if u google CCD.
I really hope you can get this sorted......must be a big worry for you.
xRx