More than loveable behaviour?

A cat's temperament and behaviors will change as they get older. I have an older cat who used to be extremely loving when he was younger but prefers solitude in his old age. My sister's cat used to never make a 'mess' on the carpet when he was younger but in his old age he has made a habit of it. I would recommend doing some research and keeping an eye out for any other changes because they could be indicative of an illness prevalent in older cats.