I would imagine any living thing can be depressed.If your cat has had a partner or has been with you and you have more animals and you have lost one of them then it is possible.Animal mates that have either been split or lost each other do and will pine so yes its highly likely.Regards
yes if its not being given the right amount of attention and stimulation (im not saying that you are). I f it continues she can start to eat or chew at her paws this is a sign of anxiety. Male ctas seem to suffer more than females unless the female has had kittens and they have been removed from her to sell. hope this has helped