What are the negative results with Zoloft and dementia patients?

My Mom has dementia and it seems the Zoloft has made her worse. Just spoke with the Doc and she says we'll get her off and try something else like Paxil. She didn't say that drug could have worsened her symptoms and I was curious if anyone out there might have an opinion on this,it's hard to tell if it's the meds or the dementia getting worse. Thanks.