Q: Mom Takes Lithium, 4 Antidepressants and has Paranoia.
Now, her doctor may know a lot more about the circumstances than I do, so I could be way wrong and she/he could have some specific reasons for using the multiple-antidepressants approach. So this is only something to wonder about, this antidepressants-inducing-cycling? question. But it's an important one, and any good psychiatrist should be able to handle having the question asked. If there were some component of cycling being induced by antidepressants, then it might be that your mother could respond to an approach where multiple mood stabilizers were used together. Even Risperidone, a newer "atypical" antipsychotic with some fairly strong antidepressant effects, might help -- it could target the paranoia specifically, and is often very well tolerated in older folks (if your mother was over 55-60 years old, for example) at very low doses.
So, I think it's okay to wonder out loud about other approaches like this and see if the doctor can think with you about alternatives. Remember she/he could be extremely overloaded and probably feels she doesn't have time to talk with families much, because there isn't even really enough time to talk with the patient herself.