Cat's Gone Crazy? No, Just Senile

Mental disorders associated with aging, including Alzheimer's, are far more common in domesticated cats than previously realized, with more than half of all cats over age 15 showing signs of senility, according to a forthcoming Journal of Small Animal Practice paper. The behaviors associated with senility in cats range from acting disoriented to changes in their social relationships, to shifting sleep habits. They may also include inappropriate vocalizing, forgetting commands, breaking housetraining, pacing, wandering, sluggishness, unusual interest or disinterest in food, and decreased grooming and confusion, such as "forgetting that they have just been fed." (via)