My son is 16 and has Down's Syndrome. He got sick with a virus. The virus affected his muscles and made him dizzy. His personality changed. This happened on New Year's day. He has had an MRI, EEG, numerous blood tests, and also a strep test. All the tests came back normal. I was told by the neurologist that he was psycotic. And also the pediatrician. I was refered to a phycologist. My son is now on Inveg 3mg and Zoloft. I do not believe the diagnosis. His personality changed instantly. I believe that because he can not speak for him self he is being written off. One thing that led me to this site is one of the many pediatricians that we have seen said that she noticed he was having alot of tics. I then looked up tics on the web and found this site. Thank you for being here and helping others. The thing is alot of his symptoms match PANDAS. The only one that does not match is that the strep test came back negative. Is it posible that other viruses could also cause PANDAS? He did have a virus when his personality changed. Now that it has been 3 months, he is getting better. He is talking more and is doing things more for himself. Please help me figure this out I feel alone. Even the pediatrician that has seen him since he was 3 isn't much help. His only reply to the problem was that yes, my son has gone through quite a personality change, but didn't I know that having Down's puts him at a high risk for dementia? My son has never taken any medications before. He was high functioning. I do not believe he just became psycotic in the blink of an eye. Thank You for taking the time to read this. I hope that someone can help me.