3 Distinct Paths of Intellectual Development May Provide Clues about Prognosis
A longitudinal study from MIND Institute researchers at UC Davis determined that changes in the IQ level of children with autism can help predict their communication and behavioral skills trajectory in adolescence. Participants for this research came from the MIND Institute’s comprehensive Autism Phenome Project. The study’s design included following subjects from age 3 through adolescence and collecting information on their behavioral and autistic characteristics. Researchers evaluated participants’ IQ at time points: T1 (mean age of 3 years), T2 (mean age of 5.6 years), and T3 (mean age of 11.5 years). Based on these assessments, participants were divided into three groups:
- “Changers” described those who began with low IQs in early childhood, followed by a substantial increase that slowed as they entered middle childhood. “Changers” made up 39% of the participants.
- “Persistent Intellectual Disability” described individuals who began with a below-average IQ that continued through childhood. Approximately 45% of the participants were in this group.
- “Persistently High IQ” described the individuals who started with an average or above average IQ that remained constant throughout childhood. Around 16% percent of subjects belonged to this group.
The team then analyzed changes in autism traits and communication adaptive functioning (i.e., the ability to understand language, engage in meaningful verbal expression, and read and write over time) for these three groups. They also examined internalizing behaviors like anxiety or depression and externalizing behaviors like impulsivity or aggressiveness. Of the 191 participants, 10 lost their autism diagnosis. This number was comprised of 5%“Changers” and 10% of the “Persistently High IQ” group. No participants in the “Persistent Intellectual Disability” group lost their diagnosis.
The authors point out that both the “Changers” and “Persistent Intellectual Disability” groups had lower IQ scores in early childhood. But children who exhibited improved communication adaptive function and decreased externalizing behaviors by adolescence were more likely to be considered “Changers.” MIND Institute Associate Director, Majorie Solomon, expands on these developmental outcomes by stating, “It is striking that we found so much overlap in individuals following different trajectories of intellectual development when assessed at the early childhood and adolescent time points. Of course, many other factors are involved in determining outcomes, but intellectual ability level is a core feature and an important starting.”
