van der Miesen, Anna I.R. et al. Journal of the American Academy of Child & Adolescent Psychiatry , Published online April 2018-05-27

This study of over a thousand children aged 6-12 years showed that rates of mental health problems in gender-nonconforming children were as high as those in gender-disordered children, suggesting that this group is at higher risk than previously thought.

https://www.jaacap.org/article/S0890-8567(18)30217-X/fulltext