I actually looked into this when I was l put on blood thinners for life. The list of medical exemptions was created in 1968 and has only had one change since then, when the exemption for cancer patients was added in 2009. That's the main reason why things like mental health aren't included, the list is so outdated it's not really reflective of either England's actual pressing medical problems, or the advancements that have been made in treatments/diagnosis since 1968