Autism combined with high IQ increases risk of suicidal thoughts

Date: Wednesday, March 1, 2023

Unexpected finding raises concern for twice exceptional (2e) youth 

Twice exceptional youth—children who have a diagnosis of autism and who also have exceptional cognitive ability—are at increased the risk of suicidal thoughts, according to a recent study by researchers at the University of Iowa. 

Specifically, the study found that autistic children are almost six times more likely to have thoughts of suicide if they have an IQ of 120 or higher than if they have average IQ.  

This finding is both unexpected and concerning because high cognitive ability is generally considered to be protective against suicidal ideation, and because suicide rates are already significantly higher in autistic individuals. 

Jacob Michaelson, PhD

The conventional wisdom is that higher IQ leads to better outcomes, period. Whether you are talking about neurodevelopmental conditions like ADHD or autism, neuropsychiatric conditions like schizophrenia or bipolar disorder, or neurodegenerative diseases like Parkinson’s or Alzheimer’s,” says Jacob Michaelson, PhD, UI associate professor of psychiatry and senior author of the study. “If you don’t look at diagnosis, higher IQ results in fewer thoughts of suicide. However, if you look at IQ among autistic people, we found the opposite—that higher cognitive ability is significantly related to more suicidal thoughts in autistic children. 

Moreover, autistic people in general have a higher risk for suicidal thoughts, but this study suggests the effect is especially profound for those with very high IQ,” he adds.

Largest genetically informed study on 2e and suicidal thoughts 

Twice-exceptionality” (2e) describes highly gifted individuals who also have neurodevelopmental differences or conditions such as autism, attention-deficit hyperactivity disorder, anxiety, or depression. The UI is home to a multidisciplinary cohort of researchers who aim to improve understanding of 2e, from its genetic roots to the best way to help 2e individuals throughout their lives. 

The new study, published in the January issue of Neurobiology of Learning and Memory, was led by Michaelson, who also is a member of the Iowa Neuroscience Institute, and first author Lucas Casten. It is the largest genetically informed study to date of risk factors for suicidal thoughts in autistic youth, and the first to examine the relationship between autism, exceptional cognitive ability, suicidal thoughts, and genetics across multiple large samples of children. 

The study included data from three large groups of children:   

  • Almost 7,000 children from SPARK, (Simons Foundation Powering Autism Research for Knowledge), a nationwide genetic study of autism. 

  • Over 1,000 high academic achievers with a range of neurodevelopmental conditions, including autism, from the Belin-Blank Center at the UI. 

  • Almost 12,000 children from the general population ABCD cohort, an ongoing longitudinal study of typically developing children in the United States. 

The UI researchers used a variety of methods to measure IQ in the study participants, ranging from gold standard clinical assessments to genetic predictors of IQ. They combined this information with clinical diagnoses of autism, and rates of suicidal thinking, obtained from parent-reported data about the child’s thoughts of suicide, to determine the relationship between suicidal ideation, diagnosis of autism, and IQ. 

The study shows that in non-autistic youth, high IQ was a protective factor against thoughts of suicide. Strikingly, the trend was the opposite in autistic youth, where those with exceptional cognitive ability were at increased risk for suicidal ideation.

By directly comparing the rates of suicidal ideation in 2e individuals with the rates in IQ-matched non-autistic people, the team found that the presence of autism is a critical factor in the relationship between cognitive ability and suicidal thoughts. 

The study is also the first to show a genetic relationship between propensity for high cognitive ability and suicidal thoughts. The study found that elevated genetic predictors for cognitive performance were associated with increased suicidal ideation. 

Notably, similar trends were found in parents of these autistic youth, with higher genetic predictors for academic success in the parents being associated with increasing thoughts of suicide, even though most of these parents do not have a diagnosis of autism. This suggests that latent genetic risk factors, and not simply having a diagnosis, likely combine with high IQ to increase suicidal thoughts. 

Exterior shot of the John and Mary Pappajohn Biomedical Discovery Building
The Pappajohn Biomedical Discovery Building, home to the Iowa Neuroscience Institute.

UI research aims to help twice exceptional kids thrive 

Taken together, the findings suggest that on a genetic level and in terms of observed behavior, high cognitive ability is an unexpected risk factor for suicidal ideation in individuals diagnosed with, or at risk for, autism. 

We looked at this from multiple angles and across multiple large samples of individuals and found this effect to be consistent,” Michaelson says. “As a result, we have a lot of confidence that the main finding is robust. 

“Our overarching goal is to help autistic people to thrive. We hope that by drawing attention to this issue we can help strengthen the education system, psychiatric care, and home life to anticipate these challenges and better equip high-ability autistic people to successfully deal with the unique challenges they will face as they grow into adulthood,” he says. 

In addition to Michaelson and Casten, the UI team also included Taylor Thomas; Alissa Doobay, PhD; Megan Foley-Nicpon, PhD; Sydney Kramer; Thomas Nickl-Jockschat, MD; Ted Abel, PhD; and Susan Assouline, PhD. 

The study was funded in part by grants from the Simons Foundation and the National Institutes of Health and also supported by the University of Iowa Hawkeye Intellectual and Developmental Disabilities Research Center. More information about enrollment can be found here.