The 60-year-old told The Telegraph that the NHS was not “getting the basics right” and was stopping these people from “living economically productive lives” amid growing youth unemployment.
She said integrated care boards (ICBs), which run local NHS services and are responsible for commissioning these services, were themselves “not clear about the rules, and therefore will give conflicting and confusing advice to a patient”.
Complaints about how the NHS treats ADHD and autism patients have tripled in the last five years, PHSO data show.
“We see quite a few examples of where there is a lack of clarity. An example I feel particularly strongly about is where a patient thinks they are doing the right thing by getting a diagnosis from a private sector provider,” she said. “But the ability to have confidence and clarity as to who will fund the medication to follow is really important.”
Ms Sussex, who was formerly the chief executive of the Student Loans Company, said there were “often delays in navigating the system” and “inconsistency of treatment”.
“A postcode lottery also means that those individuals cannot live economically independent, economically productive lives,” she said, with the 42 ICBs in England needing clearer and uniform guidance on “how to translate these rules”.
“One of the reasons we’re worried about this is that it’s reasonable to assume there will be more and more provisions of diagnoses online, perhaps provided by private providers, and so therefore, the ability to have confidence and clarity as to who will fund the medication to follow is really important.”
She said patients should be told up front if they would then have to pay for their own medication so they could “make rational choices”.
Only one in nine have a diagnosis
The proportion of prescriptions for ADHD medication dispensed privately rather than on the NHS has risen from 2 per cent to 12 per cent between 2018-19 and 2023-24, according to the charity ADHD UK.
Some 2.5 million people are estimated to have ADHD by the NHS, but only about one in nine have a diagnosis.
At the same time about a third of so-called Neets – not in education, employment or training – aged 16 to 24 have ADHD, an NHS taskforce concluded.
Its review found ADHD alone was costing the UK economy about £17bn a year in lost tax receipts and benefits.
Andy Burnham, the prime minister in waiting, has suggested that he would back the NHS’s recommendation of “investing to save”, rather than making “crude” cuts to reduce Britain’s spiralling welfare bill.
He said he wanted to reduce youth unemployment by improving mental health support and boosting work placements and apprenticeships.
A separate review found the number of women aged 20 to 24 with ADHD or autism had doubled since the pandemic.
The PHSO received 1,115 complaints relating to ADHD and autism in 2025-26, up from 347 in 2021-22.