I've been on antipsychotics for 15 years. I don't believe I have any brain damage. I haven't heard anything so severe as that except in posts by people who hate medications. Obviously there are people out there that spread false or exaggerated information about things. It's hard to always know what information online is true and what is not.

I'd believe your doctor over anything you read in some miscellaneous online article. However, if you feel you have cognitive issues, definitely bring them up with your doctor.