Queens College Professor Kristina Denisova Establishes First Link Between Low IQ in Infants and Greater Risk for Childhood Autism
–Findings could positively impact underserved populations prone to high autism rates and delays in the age of first diagnosis–
Flushing, NY, November 14, 2022—A new study, “The importance of low IQ to early diagnosis of autism,” in Autism Research, led by Kristina Denisova, associate professor of psychology and neuroscience at Queens College, establishes for the first time that infants with very low IQ are at risk of developing childhood autism spectrum disorder (ASD). In addition, both verbal and non-verbal delays suggest the need for early evaluation and intervention. While many researchers accept the importance of verbal delays, a breakthrough finding of Denisova’s study shows that any sign of lower cognitive ability—for example, not transferring toy blocks between two hands during play or not actively looking for a utensil such as a spoon when dropped–is potentially important. The study was supported by funding from the Simons Foundation Autism Research Initiative and the National Institute of Mental Health of the National Institutes of Health (NIMH).
“Professor Denisova is an expert on autism who has conducted extensive research in the field,” says Queens College President Frank H. Wu. “Her new findings have enormous implications for clinical practice with children, particularly those from underserved populations. We may have been leaving an important diagnostic tool on the table without realizing it.”
Autism researchers already knew that many children with ASD also have low IQ scores and accept that verbal delays are reliable signs of ASD. About 35% of eight-year-olds with ASD in the United States have intellectual disability (ID), meaning an IQ below 70. However, low IQ was not believed to be a major feature of ASD, and no previous prospective study looked specifically at the cognitive abilities of infants from the general population in order to assess their risk for autism.
Denisova found that if an infant has low verbal or non-verbal early cognitive abilities, there is a 40% greater likelihood of developing ASD in childhood. Her findings should pave the way for parents and caregivers of infants to seek a medical evaluation at any sign of atypical cognitive development, and she hopes this will be especially helpful to underserved populations, in particular African American and Hispanic families. Rates of both ASD and ID are especially high in children in the African American community, and often there are delays in age of first diagnosis of their children.
“Low IQ can be considered an early sign of abnormal brain development that leads to autism,” suggests Denisova. “Early low IQ scores in early diagnosed children in this study may be an indicator of the impaired integrity of nascent neurodevelopmental function or structure. These children may differ in the cause of their condition from individuals who receive diagnoses in adolescence or adulthood and whose IQ scores are in the average range. The early-diagnosed individuals (versus later-diagnosed children) may need different clinical management and treatment.” She believes that future research may need to conduct magnetic resonance imaging (MRIs) scans of the brain structure and function of at-risk infants and to follow up as they grow.
Previous studies by Denisova’s lab had identified IQ as an important, and underrated, factor in ASD. She studied infants having an older sibling with ASD, whose family history shows a high genetic risk for it. Her research indicated that regardless of whether they went on to develop ASD themselves, these infants had lower cognitive ability than their low-risk peers.
In her new study, Denisova set out to ascertain specifically whether infants having low IQ were at risk of developing ASD by ages two to four, which would allow for earlier and therefore more effective intervention and supports for children and families. “The average age at ASD diagnosis is relatively late, around four to five years, highlighting the importance of establishing early and reliable ASD markers,” she explains. “Earlier evaluation, diagnosis, and treatment could alleviate the burden for families and society associated with an ASD diagnosis, which is estimated to reach $276–1,011 billion by 2025 in the United States.”Denisova and a graduate student researcher Zhichun Lin—then a researcher at the Denisova lab at Queens College, now at Northwestern University—investigated infants’ early IQ based on a dataset from the National Institute of Mental Health Data Archive (NDA). NDA is a collaborative informatics system created by the NIH to provide a national resource to support and accelerate research in mental health. The study population was representative of participants involved in NIH-funded research in the United States, mainly on atypical development. Consisting of more than 8,000 infants, the data subsumed over 15,000 assessments (including longitudinal) of infants between two and 68 months old, based on standardized observational instruments of early learning.
This research established that IQ scores were consistently lower for ASD children. Infants diagnosed with ASD by two to four years had significantly lower IQ (both verbal and non-verbal) in infancy when compared with both Typically Developing (TD) children and a different group in which ASD was not detected, but that had other developmental concerns (such as language or learning delays). The pattern of early low IQ in ASD persisted even after excluding participants with neurogenetic conditions known to associate with ASD and ID (e.g., Fragile-X).