Overview

The Trans Youth Care United States (TYCUS) study is a federally funded research project. Since 2015 it has followed young people starting puberty blockers or cross-sex hormones at four US paediatric gender clinics. Its principal investigator is Dr Johanna Olson-Kennedy, who was then medical director of the Center for Transyouth Health and Development at Children's Hospital Los Angeles (CHLA). One part of the project tracked 95 children in early puberty who were starting puberty blockers, to see whether their mental health improved.

In October 2024 The New York Times reported that Olson-Kennedy had not published the puberty blocker results. She said the drugs had not improved the children's mental health and that she feared the finding would be "weaponized" (Ghorayshi 2024, NYT). Members of Congress began inquiries. A preprint appeared in May 2025 (Olson-Kennedy et al. 2025). In August 2026 the project's final report to the National Institutes of Health (NIH) was made public by a conservative watchdog group that had pursued its release (Oversight Project 2026).

Background

The study and its aims

The TYCUS network joined four academic gender clinics: CHLA, Boston Children's Hospital, the Lurie Children's Hospital of Chicago, and UCSF Benioff Children's Hospital in San Francisco. The NIH's child-health institute funded it under grant R01 HD082554, which was reported as worth about $9.7 million. The published protocol describes a longitudinal observational design. Researchers recorded outcomes for youth already receiving treatment at these clinics. There was no untreated comparison group (Olson-Kennedy et al. 2019, protocol).

The protocol set two aims (Tanner stages are the standard scale of physical puberty, from 1, before puberty, to 5, adult):

• to evaluate how puberty blockers given at Tanner stages 2–4 affect "mental health, psychological well-being, and metabolic and physiologic parameters including bone health", and
• to assess the effects of cross-sex hormones in an older cohort.

For both cohorts, the team said it would study changes in "gender dysphoria, depression, anxiety, trauma symptoms, self-injury, suicidality, body esteem, and quality of life" (Olson-Kennedy et al. 2019). According to the NYT, a progress report to NIH predicted that the blocker group would show fewer symptoms of depression, anxiety and suicidality, and better body esteem and quality of life, after two years (Ghorayshi 2024).

Why the result mattered

The use of puberty blockers for gender dysphoria rests largely on Dutch research. The best-known study is a 2011 follow-up of 70 adolescents, which reported less depression and better functioning after suppression (de Vries et al. 2011). A UK attempt to reproduce this at the Tavistock's Gender Identity Development Service (GIDS), England's national youth gender clinic, found no overall change in psychological function (Carmichael et al. 2021). Systematic reviews have since rated the evidence for blockers as weak or very low certainty (Cass 2024; Miroshnychenko et al. 2025). A large US cohort was therefore expected to carry weight in a field short on data, and in US litigation where Olson-Kennedy had acted as an expert witness. For the wider evidence, see Puberty Blockers and Evidence Reviews.

The hormone cohort was published first. A 2023 paper in the New England Journal of Medicine on 315 youth reported small improvements in depression, anxiety and life satisfaction. It also recorded two deaths by suicide during the study (Chen et al. 2023).

What was revealed

The New York Times report (23 October 2024)

Azeen Ghorayshi reported that Olson-Kennedy "said she had not published a long-awaited study of puberty-blocking drugs because of the charged American political environment." According to the article, Olson-Kennedy said puberty blockers "did not lead to mental health improvements, … most likely because the children were already doing well when the study began" (Ghorayshi 2024). She was quoted directly:

"They're in really good shape when they come in, and they're in really good shape after two years." — Johanna Olson-Kennedy, quoted in (Ghorayshi 2024, NYT)

"I do not want our work to be weaponized. It has to be exactly on point, clear and concise. And that takes time." — Johanna Olson-Kennedy, quoted in the NYT, as reproduced by (Washington Times 2024)

The NYT also reported her concern that opponents would use the result to argue "we shouldn't use blockers because it doesn't impact them". It said the "really good shape" description "seemed to contradict an earlier description of the group", in which the team had noted that a quarter of the adolescents were depressed or suicidal before treatment (Ghorayshi 2024). An NIH spokesperson told the paper that the agency leaves the timing of publication to researchers but encourages them to publish (Washington Times 2024). The NYT also quoted Amy Tishelman, a psychologist and co-author of the study protocol: "I understand the fear about it being weaponized, but it's really important to get the science out there" (as reproduced by The Maine Wire 2024, a conservative outlet).

The May 2025 preprint

About seven months later the team posted Mental and Emotional Health of Youth after 24 months of Gender-Affirming Medical Care Initiated with Pubertal Suppression on medRxiv. It has not been peer reviewed (Olson-Kennedy et al. 2025). What the paper actually reports:

Source: (Olson-Kennedy et al. 2025, PMC full text).

On its own data, the preprint confirms the NYT's central point: there was no measurable improvement in depression, emotional health or parent-reported problems. It also partly supports Olson-Kennedy's description. Average scores were below clinical cut-offs, and most children scored in the average range. Even so, more than a quarter had elevated depression scores at entry, and fewer than one in four reported lifetime suicidal ideation (20 of 94), so "doing well" was true of the average but not of every child. The paper does not report gender dysphoria, anxiety, body esteem or quality of life, although the protocol named all of these as outcomes. Its two counts of how many participants started hormones also disagree with each other.

The final NIH report (released August 2026)

According to a press release from the Oversight Project, the group received the final report of The Impact of Early Medical Treatment in Transgender Youth from NIH in the week before 28 August 2026, "after an extended fight to obtain its release" (Oversight Project 2026). The Oversight Project is a conservative watchdog group that files Freedom of Information Act requests and sues the government to obtain records (Howell 2025, Senate testimony). 1792 Exchange, a conservative group, said the report had been submitted on 6 January 2026 and that the Oversight Project "was forced to sue" for it (1792 Exchange 2026). This page could not independently confirm the court filing. The report itself has been published only through The Daily Signal, a conservative outlet, which quoted it as saying:

"Over 2 years of medical intervention that started with blockers, mental health remained relatively stable and was on par with the population at large. These youth showed no worsening of their mental or emotional health and suicidality decreased from baseline to 24 months." — final NIH report, quoted by (Daily Signal 2026)

The Daily Signal also quoted the report as saying that "about half" of "these youths" had clinically concerning depression and anxiety scores at baseline, "about two-thirds" reported thoughts of suicide, and "about one-quarter" reported a suicide attempt. It said the report described higher life satisfaction and lower depression and anxiety after two years (Daily Signal 2026). These baseline figures do not match the blocker cohort in the preprint. They are closer to figures reported for the project's older youth who had not received blockers (about two-thirds with suicidal ideation, per Reed 2024), so they probably describe the older hormone cohort, but the reporting does not make this clear. A second Daily Signal article said the report discussed possible effects on bone density, heart health, height and fertility (Daily Signal 2026b).

In short, the final report frames the blocker results as stability without improvement, which is the same finding as the preprint. Headlines such as "puberty blockers failed to improve youth mental health" and the Oversight Project's statement that treatment "does nothing to improve their mental health" are the groups' own interpretations, not the report's wording.

Responses

Olson-Kennedy and CHLA

Olson-Kennedy's public explanation is the one given in the NYT interview: the children started in good mental health, the result could be misused in court, and the paper needed to be "exactly on point". The NYT also reported that she said she was still analysing the data, and that she felt clinical experience with large numbers of patients was undervalued compared with small studies (KATV/TNND 2024). The preprint is the team's fullest response. In it they argue that because older youth with gender dysphoria often have poor mental health, stability suggests that blockers "prevent the deterioration" (Olson-Kennedy et al. 2025). When the final report came out in August 2026, The Daily Signal said that "neither the hospital nor Olson-Kennedy, now in private practice, responded" to its inquiries (Daily Signal 2026b). This page found no public statement from CHLA about the study itself.

Researchers and commentators critical of the study

• Jesse Singal, a journalist who has long criticised the evidence for youth gender medicine, listed what he saw as the preprint's main problems: outcomes changed from the protocol without explanation (possible "HARKing", or hypothesising after results are known), 38% loss to follow-up not discussed, uncontrolled confounders such as psychotherapy and medication, and confusion over what blockers are meant to achieve (Singal 2025).
• The Society for Evidence-Based Gender Medicine (SEGM), a group of clinicians and researchers critical of paediatric transition, called the preprint the second failed attempt to replicate the Dutch results, after Carmichael et al. It said the "prevents deterioration" claim "remains unsupported, as the study lacked a valid comparison group of untreated youth" (SEGM 2025).
• Dr Kurt Miceli of Do No Harm, a group that campaigns against youth transition, said the conclusion "resembles a hypothesis rather than a definitive finding" (Washington Examiner 2025). Do No Harm later said that "a significant amount of data reportedly collected by this grant thus far remains unreported" (quoted by 1792 Exchange 2026).
• Camilo Ortiz, a clinical psychology professor, wrote after the NYT story that "a real scientist accepts what the data show and has an allegiance to the truth" (Washington Times 2024).

Defenders and supporters of youth gender medicine

• Erin Reed, a trans advocacy journalist, called the NYT story "highly misleading". She noted that the Trans Youth Care (TYC) network had produced 28 peer-reviewed papers, that blockers are meant to prevent the effects of puberty rather than to "improve" mental health, that TYC youth who had not received blockers reported far more suicidal ideation (66%), and that the blocker sample was small (Reed 2024).
• The preprint authors cite other studies in which blocker use was associated with fewer emotional and behavioural problems, and argue that their results are "consistent with the prior literature" (Olson-Kennedy et al. 2025).
• Olson-Kennedy co-authored a 2024 critique of England's Cass Review, hosted by Yale's Integrity Project. It argued that the review misused evidence. That critique has itself been criticised in a peer-reviewed paper in Archives of Disease in Childhood (SEGM summary; ADC 2025).

Political responses

Republican lawmakers wrote a series of letters to the NIH. House Oversight subcommittee chair Lisa McClain called the delay "an irrefutable example of politicization of scientific research" and requested grant documents (House Oversight 2024; Just the News). Senators led by Bill Cassidy asked for the annual progress reports (Senate HELP 2024; The Hill). Senators Marco Rubio and Rand Paul wrote separately to the then NIH director, Monica Bertagnolli (Rubio; Paul). These letters set out the lawmakers' positions. None of them is a finding by an investigating body.

Investigations, legal and regulatory outcomes

As of October 2026, there is no public record of any NIH, institutional or regulatory finding against the researchers. The NIH's 2024 position was that the timing of publication is a matter for the researchers (Washington Times 2024).

The CHLA closure

CHLA announced in June 2025 that it would close the Center for Transyouth Health and Development, along with its gender surgery programme, on 22 July 2025. The centre had operated for about three decades. In a letter to staff, the hospital cited "California's deepening budget crisis, President Trump's executive orders, proposed federal legislation and rulemaking, and growing economic uncertainty". It described the decision as "painful and difficult" and said it could sustain operations for only about 50 days without federal funding (LAist 2025). A message to families said there was "no viable alternative", and also cited directives from Attorney General Pam Bondi and federal inquiries (CNA 2025). CHLA's stated reasons did not mention the study or the publication controversy. Linking the two is a matter of interpretation.

The Breen lawsuit

Olson-Kennedy is a named defendant in Breen v. Olson-Kennedy, a medical negligence suit filed by a former CHLA patient who later detransitioned. The case is covered on its own page, Breen v. Olson-Kennedy. This page does not discuss its merits. As of October 2026 the trial court had entered judgment for the defendants on limitation grounds, and an appeal was pending.

Significance and wider impact

• A replication that did not replicate. The TYCUS blocker cohort is the largest prospective US group of children starting blockers in early puberty. Like the UK's early intervention study, it did not reproduce the improvements reported in the Dutch study (Carmichael et al. 2021). Without a comparison group, "stable" cannot show either benefit or harm. This fits the "very low certainty" rating in recent systematic reviews (Miroshnychenko et al. 2025).
• The rationale for blockers has shifted. The protocol predicted improvement. The preprint argued instead that blockers prevent deterioration. Critics see this as moving the goalposts after the results were known. Supporters say it was always the main purpose of blockers. Either way, the change has affected how families are told about blockers. See Informed Consent.
• Publication bias in a contested field. A lead investigator said publicly that the risk of a result being "weaponized" was a factor in how and when to publish. This is the core of the controversy, whatever the actual length of the delay. For the suicide and transition debate in particular, unpublished null results distort the evidence that clinicians and courts rely on.
• Most did not stop at blockers. By the preprint's own figures, at least a third of participants started cross-sex hormones within two years. Some critics argue this is evidence of a pipeline from blockers to hormones.
• Research access is now political. The final report reached the public through partisan litigation and partisan media, not through a journal. The same researchers' field has also been hit by federal funding cuts. This makes it harder for any reader to get a neutral account.

Criticisms of how the case has been framed

Framing has been contested on both sides:

• "Hid" or "buried" versus "delayed". Conservative outlets describe the study as "suppressed" or "hidden" (Blaze; The Federalist). Olson-Kennedy disclosed the main result herself in an on-the-record interview, and the preprint appeared about seven months later. Erin Reed argued that the project's wider output undercuts any claim of concealment (Reed 2024). Those papers mostly concerned other cohorts and questions, however, and the blocker outcomes had reportedly finished being collected in 2021 (Ryan 2025).
• "Failed" versus "stable". Advocacy groups opposed to youth transition summarise the final report as showing that blockers "do nothing". The report itself describes stable mental health, no worsening and less suicidality (Daily Signal 2026). With no comparison group, the data cannot show that blockers caused either the stability or the drop in suicidality.
• "Prevents deterioration" is untested. The authors' preferred interpretation depends on comparing their cohort with other older, untreated youth. As SEGM and Do No Harm noted, the study cannot test this (SEGM 2025).
• "Good shape" versus "a quarter depressed or suicidal". Both statements are partly true. The group's averages were in the normal range. A substantial minority had elevated depression or a history of suicidal ideation (Olson-Kennedy et al. 2025).
• Mixing cohorts. Some coverage of the final report applies figures from the older hormone cohort to the 8–16-year-olds on blockers, or the other way round. Readers should check which cohort a statistic comes from.

What detransitioners say

On r/detrans, the NYT story was discussed as confirming long-held distrust of the research behind youth transition. A recurring theme in these accounts is that the people who designed and ran the studies were also the strongest advocates of the treatment:

Not publishing the findings because they're worried about what it would do politically is why we shouldn't immediately trust any study. Clearly these people have an agenda and anything that goes against it either doesn't get published or gets "massaged" to meet whatever message they want to push. —chasingmars, detrans male

Several commenters noticed the contradiction the NYT had raised:

So she said puberty blockers did not lead to mental health improvements because the children were already doing well when the study began, yet before the trial started she and her colleagues noted that one quarter of the adolescents were depressed or suicidal before treatment. —ComparisonSoft2847, desisted female

Others were people who had taken blockers at the same age as the study's participants and wrote about the physical effects they live with:

In the study, it said the mean age was about 11 and a half, which was about the age I was. … I'm a sophomore boy in highschool with most 8th grade girls being taller than me, my muscles and bones are so extremely weak, and I feel a mile behind every boy in my grade when it comes to development. —Appropriate-Most-969, detrans male

My parents genuinely wanted the best for me and were only given affirmative information and resources. Now, I'm a 15 year old female with a deep voice and masculine face, and I just recently chose to go off blockers and T. I feel like a science experiment, and I'm just basically waiting to see what will happen with my body. —redactedchicken

Some made the methodological point that also appears in published critiques:

Wouldn't a better study track both adolescents who started and didn't start (but remained trans-identifying) to see both groups outcomes? —ReasonableTable401, desisted male

These are personal accounts from a self-selected community. They cannot show whether the study's participants were harmed. They do show why many detransitioners read "no change" as "no benefit, with known costs". For first-hand accounts of blockers, see Puberty Blockers and the video archive.

Trans perspectives

Many trans commenters see blockers as preventing irreversible changes, not as treatment for depression. This is close to the authors' "prevent deterioration" argument:

Blockers simply prevent the irreplaceable effects of the wrong puberty, allowing someone to achieve far better results from HRT a few years later. —transbianbean, trans woman (MTF)

I know for myself, if I had been able to get puberty blockers before natal puberty left its scars, I wouldn't have needed top surgery later on.. —_delgrey, trans man (FTM)

The CHLA closure was experienced as a loss of care, and anger was directed at the hospital rather than at the study:

Beyond disgraceful on the hospital executives because they so easily folded without any pushback, even though we all know an EO is not legally binding & the patient population went up to the age of 25. —ftisthrowaway, trans man (FTM)

These views are real and widely held among trans people. The study itself, however, did not measure gender dysphoria or physical outcomes against an untreated group, so it cannot settle this disagreement either way.

Related pages

• Gender Medicine Scandals and Whistleblowers
• Puberty Blockers: Evidence, Trans and Detrans Perspectives
• Evidence Reviews: Cass Review and Youth Gender Medicine
• The Transition Pipeline: From Social to Medical
• Breen v. Olson-Kennedy (CHLA)
• Suicide and Transition
• Informed Consent in Gender Medicine
• Iatrogenic Harm
• The Tavistock GIDS
• Study archive · Support directory

References

• Olson-Kennedy, J. et al. (2019). Impact of Early Medical Treatment for Transgender Youth: Protocol for the Longitudinal, Observational Trans Youth Care Study. JMIR Research Protocols 8(7):e14434. source.
• Olson-Kennedy, J. et al. (2025). Mental and Emotional Health of Youth after 24 months of Gender-Affirming Medical Care Initiated with Pubertal Suppression (preprint, not peer reviewed). medRxiv. medRxiv, PMC full text.
• Chen, D. et al. (2023). Psychosocial Functioning in Transgender Youth after 2 Years of Hormones. New England Journal of Medicine. source.
• de Vries, A.L.C. et al. (2011). Puberty Suppression in Adolescents With Gender Identity Disorder: A Prospective Follow-Up Study. Journal of Sexual Medicine. source.
• Carmichael, P. et al. (2021). Short-term outcomes of pubertal suppression in a selected cohort of 12 to 15 year old young people with persistent gender dysphoria in the UK. PLoS One. source.
• Cass, H. (2024). Independent review of gender identity services for children and young people: Final report. study page, source.
• Miroshnychenko, A. et al. (2025). Puberty blockers for gender dysphoria in youth: A systematic review and meta-analysis. Archives of Disease in Childhood. study page, source.
• Ghorayshi, A. (2024, 23 Oct). U.S. Study on Puberty Blockers Goes Unpublished Because of Politics, Doctor Says. The New York Times. source.
• Richardson, V. (2024, 23 Oct). Doctor won't publish study showing no benefit from puberty blockers for fear it will be 'weaponized'. The Washington Times (conservative). source.
• The National News Desk (2024). Doctor withholds puberty blockers study over fear results will be 'weaponized,' NYT says. KATV. source.
• The Maine Wire (2024; conservative). Medical Doctor Hid $9.7M Study Showing Children Do Not Benefit from Puberty Blockers. source.
• Reed, E. (2024; trans advocacy journalist). Fact Check: New York Times Publishes Misleading Story On Puberty Blocker Study. Erin in the Morning. source.
• Singal, J. (2025). A Critique Of "Mental and Emotional Health of Youth after 24 months…". Singal-Minded. source.
• SEGM (2025; critical of youth transition). Notable Publications in Gender Medicine, June 2025. source.
• SEGM (2024). The Cass Review, the "Yale" Report, and the Importance of Keeping Special Interests at Bay. source.
• Archives of Disease in Childhood (2025). Gender medicine and the Cass Review: why medicine and the law make poor bedfellows. source.
• Washington Examiner (2025; conservative). Controversial suppressed paper on trans youth procedures is finally published. source.
• US House Committee on Oversight (2024). McClain Probes $9.7 Million Taxpayer-Funded Study… press release, letter.
• Just the News (2024; conservative). Gender affirming catastrophe? House probes NIH for lax oversight. source.
• US Senate HELP Committee minority (2024, 5 Dec). Ranking Member Cassidy, Colleagues Demand Answers… press release, letter.
• The Hill (2024). Republican senators launch inquiry into unpublished NIH study on puberty blockers for trans youth. source.
• Rubio, M. (2024). Rubio Requests Investigation Into Potentially Manipulated Research on Puberty Blockers. source.
• Paul, R. (2024). Dr. Paul Demands Answers on Taxpayer-Funded Puberty Blockers Study. source.
• LAist (2025, 12 Jun). What the closure of CHLA's trans health care center means for trans youth. source.
• Los Angeles Times (2025, 23 Jul). End of transgender care at Children's Hospital L.A. signals nationwide shift under Trump. source.
• Catholic News Agency (2025). Los Angeles Children's Hospital to Shutter Transgender Youth Program. National Catholic Register. source.
• Do No Harm (2025, 22 Oct; advocacy group). Lawsuit Seeks Data Behind Taxpayer-Funded Study That Undercuts Support For Puberty Blockers. source.
• MyNewsLA (2025, 11 Nov). Judge Grants Judgment in Favor of CHLA, Doctors in Gender Surgery Suit. source.
• Ryan, B. (2025, 6 Jun). Long-Awaited Puberty Blockers Study Is Out In Pre-Print, Finding No Change In Kids' Mental Health. Hazard Ratio. source.
• Ryan, B. (2026, 13 Jul). NIH Funding For Top U.S. Pediatric Gender Medicine Study Has Apparently Ended. Hazard Ratio. source.
• Howell, M. (2025). Testimony of Mike Howell, President, The Oversight Project. US Senate Judiciary Committee. source.
• The Oversight Project (2026, 28 Aug; conservative watchdog). Oversight Project Secures the Release of Transgender Study After Delay from NIH. source.
• Lucas, F. (2026, 27 Aug). EXCLUSIVE: NIH-Funded Study Finds Puberty Blockers Failed to Improve Youth Mental Health. The Daily Signal (conservative). source.
• The Daily Signal (2026b, 28 Aug; conservative). Bone, Heart Risk to Transgender Youth Receiving Puberty Blockers and Hormones: Study. source.
• 1792 Exchange (2026, 28 Aug; conservative). Final NIH Report on Multi-Million Dollar Olson-Kennedy Study Shows Puberty Blockers Don't Help Kids. source.
• The Blaze (2026; conservative). Taxpayers paid $9.6 million for a gender ideologue's puberty-blocker study… source.
• The Federalist (2026, 1 Sep; conservative). Delayed Study From Pro-Trans Researcher Finds Puberty Blockers Don't Help Kids. source.