My son has an 18 year old male cat who is behaving oddly. He is obsessed with his water dish. He spends a lot of time staring at it and meowing for my son to fill it (it's already full). He is now waking my son at 4 am meowing and trilling because he wants to eat. There are 5 other cats so feeding Cosmo at 4 am is not feasible. He follows my son everywhere. We know he's acting so differently because he's getting older but these obsessions are making my son and his girl friend crazy. Cosmo has been to the vet and there is nothing physical wrong. Has anyone else had this problem? If so is there anything to be done?