Yeah, I experienced that too.
I wasn't taking them for a psychotic illness, rather BPD + anxiety, so I was lucky enough to be able to stop taking them.
The dumbing down feeling lasted for 8 months or so after I stoped taking them. I remember cooking myself a pizza, only to find I had left all of the packaging on. Another time I burnt my hands taking something out of the oven sans oven gloves.
I have been repeatedly been told that APs don't have this effect and it must just be the anxiety. I don't believe them.