It is widely agreed now that transgender people are not mentally ill, and yet, non-heteronormative people are still categorized as such by the World Health Organization (WHO) in its International Classification of Diseases (ICD). However, that may be about to change in its next revision of the list, based on a new study conducted for that very purpose and published in the journal the Lancet Psychiatry on Tuesday.

Titled “Removing transgender identity from the classification of mental disorders: a Mexican field study for ICD-11,” the field study “used a retrospective interview design in a purposive sample of transgender adults” in Mexico City to investigate if the distress and dysfunction associated with transgender identity was an inherent aspect of being transgender or if it was caused by stigmatization and social rejection.

The study starts with the premise that “the conceptualisation of transgender identity as a mental disorder has contributed to precarious legal status, human rights violations, and barriers to appropriate health care among transgender people.” Of the 250 adults who participated in the study (260 were approached), 202 had been assigned male sex at birth. The mean age at which awareness of transgender identity was reported was 5 ½ years and distress related to their identity during adolescence was reported by 208 participants.

The average level of distress was “quite high” among the participants, with 76 percent reporting social rejection, most commonly by family members. Almost two-thirds of the respondents also reported being subjected to violence due to their gender identity, again often by family members, a trend the researchers found “particularly disturbing.”

Such findings and other details led the researchers to conclude that “distress and all types of dysfunction were strongly predicted by experiences of social rejection … and violence.” Based on their conclusions, they said the “study provides additional support for classifying health-related categories related to transgender identity outside the classification of mental disorders in the ICD-11.”

The experience of distress and dysfunction is considered a defining characteristic of mental illness and in the 10th revision of the ICD, called ICD-10, WHO lists “Transsexualism,” “Dual-role transvestism,” and “Gender identity disorder of childhood” as specific illnesses, while having two other sweeping categories labeled “Other gender identity disorders” and “Gender identity disorder, unspecified.” The handbook also provides diagnostic guidelines for these disorders.

ICD-11 is the next revision, due in 2018, and “the reconceptualization and related reclassification of transgender-related health conditions in the ICD-11 could serve as a useful instrument in the discussion of public health policies aimed at increasing access to appropriate services and reducing the victimization of transgender people.”

The American Psychiatric Association removed “gender identity disorder” from the fifth edition of its Diagnostic and Statistical Manual of Mental Disorders (DSM-V) in 2012, replacing it with “gender dysphoria,” which it says removes the association of being transgender with it being a disorder, and reflects the discontent experienced by transgender people as a result of their gender identity.