This explains physically disabled treatment in china. https://www.prisoncensorship.info/archive/etext/classics/lifeundermao/deaf1.pdf https://en.m.wikipedia.org/wiki/Disability_in_China

This one is about the USSR but still relevant. https://isreview.org/issue/103/disability-and-soviet-union-advances-and-retreats/index.html

but to answer your question communism is based on “From each according to his ability to each according to his need.” so as long as the material conditions allow for it mentally disabled should be treated well. https://www.scribd.com/document/256390020/Disability-Studies-a-Historical-Materialist-View