Can race and mental disability have a connection?

My brother is autistic (somewhat high functioning. Has a drivers license but can’t keep a job)

He’s really racist towards African Americans. You can’t convince that he IS racist, and you can’t convince him that the things he says are inappropriate and rude. (He mainly makes racist jokes but he’ll make a handful a comments, too.)

Do you think the reason no one can convince him otherwise is due to his lack of social skill? Do you think that maybe there’s a connection between mental disabilities and racism? (Obviously not in all cases.)

P.S. I’m not looking for a way to justify my brother. I’m just curious as I’m white I haven’t experienced racism.