We should at least consider Theo has ADHD...
4x05 • 6x18 • 9x17
Citations & Notes + Bonus:
Bonus, Oliver Stark agrees that Buck has ADHD (which, perhaps, makes it more likely that headcanon could've made its way to the writers room....):
Notes
We would need to know more about Theo to say for sure, but I think Theo has ADHD, based on what we know so far. The genetic likelihood alone is compelling (6, 7, 8, 9), on top of him being born preterm (1, 2, 3). Theo was 2 turning 3 in 9x17 based on him being born in 6x18 (don't listen to them saying 4 years in 9x17, that makes NO sense), which is young enough that the American Academy of Pediatrics (AAP) does not usually recommend a diagnosis (10). This could explain why Connor and Kameron didn't get clear answers, if the specialists didn't want to commit in case his behavior is just him being a toddler. However, just the fact that Buck definitely has ADHD means it's very likely Theo does, too, and it could indeed be detectable at a young age (8).
Even if no one is willing to diagnose him at age 3, they might still use Parent Training in Behavior Management (PTBM) as recommended by the AAP (10, 11). After age 4, it is considered more acceptable to diagnose if he shows enough symptoms in multiple environments (home, school/daycare, with peers) for at least 6 months (4), which seems to be the case for him. To learn more: https://chadd.org/for-parents/preschoolers-and-adhd/.
There are certainly issues people have with ADHD as a diagnosis and how it's handled by society and by medical professionals. However, I don't really want to get into that for this post, and in this case Connor and Kameron clearly needed support to help keep Theo safe. I'm 100% certain Buck will also need support, especially as a single foster parent...so maybe this could still end in Buck finding out he has ADHD lol.
Also, I know these citations aren't all written properly, but this is a for-fun fandom post I made for free, so I'm not bothered about fixing them.
Citations (in order of appearance):
Papanikolopoulos, P., Papanikolopoulou, S., & Gerede, A. (2026). Preterm Birth and the Emergence of ADHD Symptoms: A Review of Recent Evidence. Medicina, 62(1), 24. https://doi.org/10.3390/medicina62010024
Navalón, P., Ghosn, F., Ferrín, M., Almansa, B., Moreno-Giménez, A., Campos-Berga, L., … & García-Blanco, A. (2022). Are infants born after an episode of suspected preterm labor at risk of attention deficit hyperactivity disorder? A 30-month follow-up study. American Journal of Obstetrics and Gynecology, 227(5), 757-e1, https://doi.org/10.1016/j.ajog.2022.05.065
Sucksdorff, M. (2021). Prenatal and perinatal risk factors of ADHD-A population-based register study. University of Turku, https://www.utupub.fi/items/b7eb869c-df81-42b7-bb84-bf2cdd3ea725
The PDF of DSM-5 criteria: https://www.aafp.org/assets/image/upload/v1746724629/adhd19-assessment-table1_ys0jux.pdf
Screenshots of Oliver Stark's tweet (he has since deleted his account): https://www.tumblr.com/filmmakingismylife16/644120130819964928/oliver-stark-tweeting-about-buck-having-adhd-this
Grimm, O., Kranz, T.M. & Reif, A. (2020). Genetics of ADHD: What Should the Clinician Know? Curr Psychiatry Rep, 22(18), https://doi.org/10.1007/s11920-020-1141-x
Uchida, M., DiSalvo, M., Walsh, D., & Biederman, J. (2023). The Heritability of ADHD in Children of ADHD Parents: A Post-hoc Analysis of Longitudinal Data. Journal of Attention Disorders, 27(3), 250-257, https://doi.org/10.1177/10870547221136251
Miller, M., Iosif, A. M., Bell, L. J., Farquhar-Leicester, A., Hatch, B., Hill, A., … Ozonoff, S. (2021). Can Familial Risk for ADHD Be Detected in the First Two Years of Life? Journal of Clinical Child & Adolescent Psychology, 50(5), 619–631. https://doi.org/10.1080/15374416.2019.1709196
Faraone, S.V., Larsson, H. (2019). Genetics of attention deficit hyperactivity disorder. Mol Psychiatry, 24, 562–575, https://doi.org/10.1038/s41380-018-0070-0
Wolraich, M.L., Hagan, J.F., Allan, C., Chan, E., Davison, D., Earls, M., ... Zurhellen, W. (2019). Clinical Practice Guideline for the Diagnosis, Evaluation, and Treatment of Attention-Deficit/Hyperactivity Disorder in Children and Adolescents. Pediatrics, 144(4): e20192528. 10.1542/peds.2019-2528
U.S. Centers for Disease Control and Prevention. (2026). Parent Training in Behavior Management. https://www.cdc.gov/adhd/treatment/behavior-therapy.html


















