Does touching patients with Down syndrome (Mongoloids) when teaching or playing with them invalidate ablution, knowing that they are not of sound mind?

Ablution is not invalidated simply by touching a person without lust, whether the one touched is sick or healthy. Evidence for this is the hadith (definition) of Aisha, may Allah be pleased with her, that the Prophet, peace and blessings be upon him, would nudge her leg while she was lying across his path during prayer. Ibn Qudamah mentioned that touching without lust does not invalidate ablution, and there is no difference in this regard between a non-mahram (definition) woman and a mahram, or between an adult and a child.