Accusations that the young are a snowflake generation are wrong, the head of an independent review into mental health, ADHD and autism has told the BBC.

Prof Peter Fonagy said in an exclusive interview that there had been a real rise in mental distress among children and young people, with anxiety, depression, self-harm and eating disorders the most common.

He said it was “harder to be young” now given the economic and employment uncertainty young people face, coupled with the challenges presented by social media.

His review was ordered nine months ago by Wes Streeting after the then-health secretary claimed in an interview that young people were over-diagnosed and “written off”.

It is likely to feed into government policies on everything from NHS services and benefits to support for young people who are not in education, employment or training.

Fonagy said he chose to speak to the BBC ahead of the publication, which is expected later this week, because he was concerned the debate around ADHD and autism would “obscure” the wider issue of mental health.

More than 100 experts and families with experience of mental health problems have worked on the review with Fonagy, a clinical psychologist and adviser to NHS England.

He said it will conclude that the rise in mental health problems since the 1990s was real, with about one in four 16 to 24-year-olds now struggling.

The data on this is contested as some sources rely on self-reporting, while sceptics argue greater awareness and reduced stigma around mental health mean more people are coming forward.

Some have also questioned whether society was now over-medicalising distress in people’s lives – giving people diagnoses when what they are facing is temporary stress that they should learn to cope with.

Last year, the BBC found that many GPs had concerns about over-diagnosis and felt normal life stresses were being over-medicalised.

NHS figures show the number of children and young people in contact with mental health services in England has risen by 50% in the past five years.