According to this report on ADHD, undiagnosed ADHD costs the UK £17 billion:
https://share.google/STyoE5m6WXon5w9Wc
It would be cheaper to fund earlier assessment and diagnosis, then give people support.
According to the Lancet, examining the diagnoses of ADHD in primary care records, 1.19% of people have been diagnosed with ADHD, which is notably low, compared to international figures on its incidence. For males under 18, 41.8% of them with ADHD are not diagnosed, and for females under 18, it’s 76.4% undiagnosed. This doesn’t fit in with pp’s claims that 10 - 20% of children in a classroom are diagnosed with ADHD at a population level.
The reason PIP is going up, is because people can’t survive on the other working age benefits, which have gone down in real terms since 2010, and the wider failures in education, the NHS and social care. Sort those out (which would lead to earlier assessment, diagnosis and treatment of many conditions) and less people would be disabled.