Is this considered a mental problem?!

Ok one of my relatives is very intelligent and is successful!.But she does this one thing that is kind of scary and I wonder if its a mental problem!.She sits up and she be cussing and fussing and theres no one there!She literally is cussing and fussing at the air!.She claims that there is this chick who likes to bother her and says that she has to back her down!.There is no one there!.She has been doing this since I was a little girl!.Even her husband has to tell her that there is no one there!.She just looks toward the wall and starts fussing and cussing and telling off someone thats not there!.OMG that is creepy and annoying!.There is no one there!.No one is saying or doing anything to her and she keeps claiming this female is there saying things to her!.I understand we all think out loud sometimes, but she is not thinking!.She fusses and cusses at someone who isn't there!.Is this a mental problem!?What is it called!?Www@Answer-Health@Com

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