Holly Cutts, an electrical engineer from Yeovil, said she was referred to a private clinic for her ADHD diagnosis because NHS waiting lists at the time were “three years long”.

The 22-year-old said her ADHD often manifested as hyperactivity, time-blindness or inattention, explaining it affected all parts of her life.

“When you have somebody telling you ‘it’s not real’ and ‘it’s all in your head and you just need to try harder’ – they don’t realise you have been trying harder than a lot of people have been the whole time,” she said.

In a statement, Channel 4 said: “This documentary does not deny the lived experience of those diagnosed with ADHD, but does present the view of an extensive range of senior medical experts – many of whom work or have worked with the NHS or have held presidential roles at professional membership bodies – who seek to question the conventional understanding of ADHD and if it is a neurodevelopmental condition.

“They also ask whether modern living has contributed to a rise in diagnoses, and whether there may be better alternatives for some children than medication.”