Roughly 15% of transmasculine and transfeminine youths in one study had attention deficit disorders.
A study  which used electronic medical records to identify transmasculine and transfeminine youths found attention deficit disorders in 15% of males and 16% of females.
 Becerra-Culqui, T.A. Liu, Y., Nash, R., Cromwell, L., Flanders, W.D., Getahun, D. Giammattei, S.V., Hunkeler, E.M., Lash, T.L., Millman, A., Quinn, V.P., Robinson, B., Roblin, D., Sandberg, D.E., Silverberg, M.J., Tangpricha, V. & Goodman, M. (2018). ‘Mental health of transgender and gender nonconforming youth compared with their peers. Pediatrics 141(5). [Link]