Up to a quarter of youngsters treated in transgender clinics may simply be autistic, according to new research.

Those attending gender identity clinics are many times more likely to show signs of autism than the population at large, doctors found.

Last night, critics said the figures called into serious question the practice of 'affirming' a young person's chosen gender and putting them forward for potentially irreversible medical treatment without a thorough examination of their psychiatric condition.

Individuals with autism spectrum disorder (ASD) are more likely than others to become fixated on an idea – be it true or false – which they can then find almost impossible to drop, warned Stephanie Davies-Arai, founder of the campaign group Transgender Trend.

Those attending gender identity clinics are many times more likely to show signs of autism than the population at large, doctors found (file image)

She said: 'We should not just be cheering on this vulnerable group towards life-changing medical interventions.'

The findings are from a review of academic literature about the prevalence of autism in people attending gender identity clinics, conducted by Australian medics.

The news comes days after former psychologists at the NHS's flagship Gender Identity Development Service (GIDS) told Sky News they feared young people were 'being over-diagnosed and then over-medicalised', adding: 'We fear that we have had front-row seats to a medical scandal.'

Writing in the Journal Of Autism And Developmental Disorders, the Australian doctors stated: 'The few studies employing diagnostic criteria for ASD suggest a prevalence of 6-26 per cent in transgender populations.'

This was 'higher than the general population, but no different from individuals attending psychiatric clinics'.

Last night, critics said the figures called into serious question the practice of 'affirming' a young person's chosen gender and putting them forward for potentially irreversible medical treatment without a thorough examination of their psychiatric condition (file image)

The Australians also quoted 'definitive findings' from a US study of almost 300,000 children, which discovered those with autism 'were over four times as likely to be diagnosed with gender dysphoria' compared to those without autism.

Gender dysphoria (GD) is the perception of a mismatch between one's biological sex and gender identity.

Last year The Mail on Sunday unearthed an internal study by GIDS in London, also known as the Tavistock Clinic, which found 35 per cent of children and teenagers referred there between 2011 and 2017 had 'moderate to severe autistic traits'.

Parents have told the MoS how they believe GIDS clinicians failed to consider properly their child's autism, and instead 'affirmed' the youngster's transgender identity and granted them medical treatment such as puberty-blocking drugs.

The Australian medics reasoned there was 'likely an over-representation of autistic symptoms in children and adolescents with GD'.

They stated there was 'the potential for misdiagnosis' and admitted those attending gender identity clinics may 'not necessarily have gender dysphoria'.

Heather Brunskell-Evans, a former research fellow at King's College London who is critical of the transgender movement, said the researchers 'could have arrived at an equally justified but contrasting conclusion from the data.

'Namely that young people presenting with GD have multiple [conditions] so that affirming gender self-identity, rather than offering psycho-therapeutic help, might be the worst approach to take.'

A GIDS spokesman said its staff were 'trained and experienced in the nuances of autism'.

She continued: 'In our experience, young people with a diagnosis of ASD – or with some indication of having features of ASD – are all very different as individuals and so we would take great care in trying to understand how the ASD might be interacting with the development of their gender identity as well as with other identity issues.'