Monday, November 24, 2025

 

Many who die by suicide aren’t depressed, genetic research suggests




University of Utah Health
Hilary Coon 

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Hilary Coon, PhD, lead author on the study.

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Credit: Charlie Ehlert / University of Utah Health






Among friends and family of those who die by suicide, a common refrain is: I didn’t know.

While some people who die by suicide have prior attempts, about half of people who die by suicide have no documented suicidal thoughts or behaviors, nor do they have known psychiatric conditions associated with suicide risk, like depression. They have no previous clear indicators that they might be at risk at all.

A new genetic study at University of Utah found that people in this group of unexpected suicides aren’t just flying under the clinical radar via lower access to psychiatric services—their underlying risk factors may be fundamentally different.

The research found that people who die by suicide without prior non-fatal suicidal thoughts or behaviors have fewer psychiatric diagnoses and also fewer underlying genetic risk factors for psychiatric conditions compared to people who had shown these warning signs before dying by suicide. 

“There are a lot of people out there who may be at risk of suicide where it’s not just that you’ve missed that they’re depressed, it’s likely that they’re in fact actually not depressed,” says Hilary Coon, PhD, professor of psychiatry in the Spencer Fox Eccles School of Medicine at the University of Utah and first author on the study. 

“That is important in widening our view of who may be at risk. We need to start to think about aspects leading to risk in different ways.”

The results, published in JAMA Network Open, upend conventional beliefs about suicide risk and suggest new approaches to help save lives.

Uncovering hidden risk

Other research had shown that people who die by suicide without prior known suicidality are less likely to have psychiatric diagnoses, such as depression, compared to people with documented suicidal thoughts or behaviors. But nobody knew the root cause of this difference. Maybe, researchers thought, people without known suicidality are still just as depressed or anxious—they’re just undiagnosed.

But Coon’s team was surprised to find that this isn’t the case. Instead, they found that this group has different genetic risk factors from people with known suicidality. By comprehensively analyzing anonymized genetic data from more than 2,700 people who died by suicide, the researchers found that people without prior suicidality tend to have fewer genetic risk factors for several psychiatric conditions, including major depressive disorder, anxiety, Alzheimer’s disease, and PTSD.

The genetic data also suggests that this group isn’t any more likely than the general population to have milder conditions, like depressed mood and neuroticism.

This means that conventional wisdom on how to reduce suicide may need to be rethought. “A tenet in suicide prevention has been that we just need to screen people better for associated conditions like depression,” Coon explains. “And if people had the same sort of underlying vulnerabilities, then additional efforts in screening might be very helpful. But for those who actually have different underlying vulnerabilities, then increasing that screening might not help for them.”

Helping those most at risk for suicide

Figuring out how to find and treat these “hidden” at-risk individuals is a major focus of Coon’s upcoming research. Previous studies with clinical data have shown potential links between suicide risk and hard-to-treat conditions like chronic pain. Coon is also investigating how other physical disorders, such as inflammation and respiratory conditions, may impact suicide risk. Her work will also focus on traits that may confer resilience to suicide.

Coon emphasizes that, on their own, individual genetic risk factors related to suicide have very small effects on risk, and there’s no single gene—or combination of genes—that causes suicide. Environmental and societal contexts are crucial contributors to risk, and understanding the interplay between the environment and underlying biology will be essential to discovering who’s at risk.

“We hope our work will begin to define subsets of individuals at risk, and also the contexts in which these risk characteristics may be important,” Coon says. “If people have a certain type of clinical diagnosis that makes them particularly vulnerable within particular environmental contexts, they still may not ever say they’re suicidal. We hope our work may help reveal traits and contexts associated with high risk so that doctors can deliver care more effectively and specifically. ” Better identification of at-risk individuals will help people get the care they need.

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Do you need help? Call 988 to reach a free, confidential 24/7 support line for suicidal crisis or emotional distress. The Huntsman Mental Health Institute Crisis Care Center also offers 24/7 walk-in mental health services for adults. Additional information and assistance can be found through the Utah Chapter of the American Foundation for Suicide Prevention.

Are you concerned about a loved one or friend? Asking is the single most effective intervention for suicide. Learn how to help.

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This research is published in JAMA Network Open as “Genetic Liabilities to Neuropsychiatric Conditions in Suicide Deaths With No Prior Suicidality.” 

The work was supported by the National Institute of Mental Health (grants R01MH122412, R01MH123489, R01ES032028, and R01MH123619), Janssen Research & Development, the American Foundation for Suicide Prevention (grant BSG-1-005-18), the Brain & Behavior Research Foundation–National Alliance for Research on Schizophrenia and Depression (grants 28132, 28686, and 31249), and the Clark Tanner Foundation. Content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

 

Why monkey studies may mislead research on cancer immunotherapy drugs targeting TIGIT



UC Davis study reveals species-specific TIGIT shedding that could distort preclinical results



University of California - Davis Health





(SACRAMENTO, Calif.) — A new study published in the Journal of Biological Chemistry from UC Davis Comprehensive Cancer Center finds that TIGIT, an immune checkpoint receptor targeted by cancer immunotherapy drugs, triggers a different response in rhesus macaques compared to humans.

The findings could have implications for cancer immunotherapy drugs targeting TIGIT.

TIGIT acts like a brake on the immune system

TIGIT (T cell immunoreceptor with Ig and ITIM domains) is a “brake” on the immune system. It sits on certain immune cells, like T cells and natural killer (NK) cells, and prevents them from attacking too aggressively. Cancer cells take advantage of this “brake” to protect themselves from the immune system.

That’s why scientists are developing cancer immunotherapy drugs to block TIGIT so the immune system can fight tumors more effectively.

However, multiple anti-TIGIT antibodies have failed in Phase III trials for solid tumors, raising questions about the underlying mechanism.

Rhesus macaques “shed” TIGIT from immune cells

The study’s new findings show that rhesus macaques — but not humans — shed TIGIT from immune cell surfaces when exposed to plasmin. Plasmin is a natural enzyme involved in blood clot breakdown. The enzyme is highly upregulated (increased) in almost all solid cancers.

This shedding creates a soluble form of TIGIT that can still bind anti-TIGIT monoclonal antibodies, such as tiragolumab, an investigational cancer treatment.

The result is that in macaques, antibodies may be soaked up by free-floating TIGIT instead of blocking immune suppression on the tumor-fighting cells.

“Currently, preclinical safety and dose estimation studies for cancer immunotherapy drugs targeting TIGIT are done in macaques,” said Jogender Tushir-Singh, an associate professor in the Department of Medical Microbiology and Immunology and senior author of the study.

“We know from our study of macaque response that the dilution of the drug away from T-cells is a problem. Tests in macaques will not predict proper safety and dose estimation data for human clinical trials,” Tushir-Singh said. “It seems like TIGIT biology and mechanism are much more complex than expected.”

Difference in amino acid makes it easier for plasmin to cut TIGIT

The researchers looked at TIGIT proteins from humans and monkeys. They made lab versions of these proteins and exposed them to plasmin to see what would happen.

They found that in monkeys, a single difference in the protein’s amino acid compared to humans (at position 119) made it easy for plasmin to cut TIGIT.

When they added plasmin to human and monkey immune cells, only the monkey cells shed TIGIT from their surfaces. They then checked whether the shed TIGIT in monkeys could still stick to cancer drugs — and it could.

TIGIT testing in macaques may produce misleading data

The researchers say more studies are needed, but the findings raise questions for current and future TIGIT-targeted cancer trials. They note that testing TIGIT cancer drugs in macaques could have produced misleading safety and efficacy data. This may help explain why TIGIT therapies have underperformed in late-stage trials.

“The study underscores the need for improved models that better reflect human biology when developing next-generation immunotherapies,” Tushir-Singh said.

Coauthors on the study include Eric Pirillo, Francis Freenor V, Brice E.N. Wamba, Sanchita Bhatnagar and Tanmoy Mondal of UC Davis Department of Medical Microbiology and Immunology.

The research was funded by the National Institutes of Health National Cancer Institute (R01CA233752) and the Ovarian Cancer Alliance of Greater Cincinnati (SP0A243532).

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Clinicians’ lack of adoption knowledge interferes with adoptees’ patient-clinician relationship



Unmet health care needs of adult patients adopted in childhood: insights and recommendations



American Academy of Family Physicians




Original Research 

Background: Researchers examined health care challenges faced by adult adoptees and how being adopted affects relationships with their clinicians. U.S. adult adoptees completed a mixed-methods online survey. A total of 204 participants were included in the final analysis. 

What This Study Found:

  • Most participants described multiple types of adoption-related bias by clinicians: More than half of the participants reported clinicians made insensitive or inaccurate statements related to adoption (68%), ignored or dismissed adoption-related concerns (60%), or made them feel uncomfortable, unwelcome, or unsupported (56%).

  • Participants who frequently experienced these negative interactions were seven times more likely to change physicians or delay care than adoptees who did not experience bias.

Five Themes Emerged From the Qualitative Results:

  • Adoptees want clinicians to recognize and address adoption as a lifelong factor with health care implications.

  • Many adoptees perceive that limited access to family medical history negatively impacts their care.

  • Adoptees with limited family medical history want to gain an understanding of their medical risks through genetic testing.

  • Clinicians’ lack of knowledge about adoption harms patients and impairs the adopted patient-physician relationship.

  • Adoptees report improved health care experiences and trust with clinicians who recognize adoption knowledge gaps, are receptive to feedback, and seek additional adoption-competent training.

Implications: The findings highlight the need for health care systems and clinicians to recognize adoption as a lifelong experience that can influence health and care access.  

Unmet Health Care Needs of Adult Patients Adopted in Childhood: Insights and Recommendations

Julia L. Small, MD, et al 

Department of Pediatrics, University of Massachusetts Chan Medical School, Worcester, Massachusetts

Department of Internal Medicine-Pediatrics, University of Colorado, Aurora, Colorado

Pre-Embargo Link (temporary)