The World Health Organisation (WHO) is moving to declassify transgender identity as a mental disorder, as it updates its category of mental illnesses for the first time in decades.

The body, which is the public health agency of the United Nations (UN), is considering making the change in a revised categorisation of mental and behavioural disorders to be released in 2018.

News of the change comes just as a new study published in The Lancet Psychiatry this week advocates that transgender identity should not be diagnosed as a mental disorder.

"Stigma associated with both mental disorder and transgender identity has contributed to the precarious legal status, human rights violations, and barriers to appropriate care among transgender people," says lead researcher Geoffrey Reed from the National Autonomous University of Mexico.

"The definition of transgender identity as a mental disorder has been misused to justify denial of health care and contributed to the perception that transgender people must be treated by psychiatric specialists, creating barriers to health care services."

Reed, who is also involved with the WHO's new classification of mental health and behavioural disorders, says the proposal to drop transgender as a disorder isn't getting opposition from within the organisation's ranks.

"The intention is to reduce barriers to care," he explained to Pam Belluck at The New York Times.

In their study, the researchers interviewed 250 transgender people aged 18–65 and found that while many had experienced distress in their lives, most of this stemmed from experiences of social rejection and violence directed at them from others – not confusion or negative feelings over their transgender identity.

"Our findings support the idea that distress and dysfunction may be the result of stigmatisation and maltreatment, rather than integral aspects of transgender identity," says lead investigator Rebeca Robles from the Mexican National Institute of Psychiatry.

"The next step is to confirm this in further studies in different countries, ahead of the approval of the WHO revision to International Classification of Diseases in 2018."

While revising the classification won't change some people's negative attitudes and behaviour towards transgender individuals overnight, the researchers think it will help to make things better in the long term – reducing the stigmatisation the transgender community currently faces.

"Rates of experiences related to social rejection and violence were extremely high in this study, and the frequency with which this occurred within participants' own families is particularly disturbing," says Robles.

"This study highlights the need for policies and programs to reduce stigmatisation and victimisation of this population. The removal of transgender diagnoses from the classification of mental disorders can be a useful part of those efforts."

The researchers acknowledge that a limitation of their study is that it consisted of volunteers only, so they suggest further research in other countries would be needed to help confirm the results. There's also the issue of – once transgender identity is declassified as a mental disorder – how then does it become classified?

While some in the community don't think it should be classified at all at this level, others point out that the extreme stigmatisation and violence transgender people experience does make it a global health issue – which means it should be classified somehow and somewhere by the WHO, to help with things like insurance and billing for medical services, or for ongoing research purposes.

"[Some transgender people] say homosexuality was declassified, so now this is part of our civil rights movement, without understanding that it's wildly different," explained women's studies researcher Karl Surkan from MIT and Temple University to The New York Times.

"[But homosexual and bisexual people are] not sort of reliant on medical treatment in the same way that the transgender population often is. You need a code to get an insurance company to pay for something."

So the issue is far from settled, but the good news is that for the first time in the decades since the WHO classifications were last revised, transgender people will be free of the burden of being told that they're mentally unwell simply due to their transgender identity – and that simple change could lead to many good things.

"It's sending a very strong message that the rest of the world is no longer considering it a mental disorder," clinical psychiatrist Michael First from Columbia University – who wasn't involved with the study but is chief technical consultant on the new WHO classifications – told The New York Times.

"One of the benefits of moving it out of the mental disorder section is trying to reduce stigma."