DWP appeal response help please

Going through DWPs submission for tribunal. They have denied certain activities due to not having physical, mental or significant cognitive impairments. However, son has Asperger's which is neurological (he also has cognitive impairments = severe dyslexia & associated weakness in working memory and phonological processing). And this is the reason he needs help. Can anyone please find me a reference from the government or dwp or anywhere stating that cognitive and neurological conditions should be taken into account. I need to counter this statement from DWP and would like to have something 'official' to back me up.
Any help gratefully received.
Thank you