Features in infancy can predict adult outcomes
This year, to make predictions about future ASD features, more studies used a longitudinal study design. This design is critical to autism research because it follows a group comprised of individuals diagnosed with ASD and, at times, individuals without a diagnosis in order to determine how they are affected as adolescents and adults. Whereas a longitudinal study can be expensive, complex and does not produce immediate results, the nature of its design provides clinicians invaluable data, affording deeper insights that allow them to more fully educate families by managing expectations, identifying focus areas and providing coping strategies that serve to help those with ASD live their best lives.
Longitudinal studies help parents understand their child’s reality and manage future expectations, as well as help scientists refine interventions according to the variability of groups of people with ASD. Multiple research studies have used data to group children based on trajectory, i.e. the progression from commencement, through adolescent development to adult functioning. The composition of these groups consists of those who show fewer symptoms and continue to improve vs. those less functioning who continue to decline. This year, two longitudinal studies, one conducted in the United States and one in Canada, closely examined toddlers to pinpoint and study specific factors that influence outcomes, from childhood to adulthood. In these studies, two patterns emerged: those possessing lower levels of symptoms who improve vs. those with more profound symptoms who decline.
While all groups showed improvement in daily living skills, those who presented less severe symptoms in toddlerhood and showed marked progression during adolescence also had the highest adaptive abilities as adults2. Although most participants showed improvement in social communication with age, improvement varied, based on individual language ability as toddlers. Social communication impairments in 19 year olds was found to correlate with differences in language ability as early as age two. As speech improved, so did this core symptom of ASD3: those with early minimal language ability showed the greatest functioning impairments as adults. Likewise, fine motor skills in infancy4is a predictor of language at age 19, in that better fine motor skills in early childhood is a predictor of better command of language in adulthood. Together, these findings demonstrate that poor early motor skills and decreased language function are related to later ASD symptoms. This is a crucial identification, considering that both fine motor skills and language are target areas of early intervention and that intervention may improve ASD through adulthood.
The study of early motor function is not only vital to further understanding how it affects those diagnosed, it also offers insight pre-diagnosis in terms of how early motor function may predict a later ASD diagnosis. The Baby Siblings Research Consortium (BSRC) is a group of researchers that studies initial features of ASD in siblings of children with ASD as young as 6 weeks of age. Siblings of children with ASD have a 15x greater probability of having ASD themselves than do other children. Similar to previously mentioned studies, BSRC also concludes that fine motor abilities at 6 months can predict an ASD diagnosis in siblings and expressive language ability in younger siblings at 3 years6,7.
Another factor BSRC researchers have employed to estimate the probability of diagnosis in children is number of siblings previously diagnosed with ASD. Those with at least 2 older siblings with ASD were found to have a higher probability of a diagnosis, as well as increased severe cognitive disabilities8. Based on family history, this information is vital in helping families better understand the probability of an ASD diagnosis in future children, as well as predicting strengths and limitations future children may face.
In addition to identifying behavioral markers, the past decade of research has revealed a blossoming of early biological factors that may serve as additional predictors of diagnosis, ranging from genetic tests9, salivary hormone markers and other reflections of altered development. Studies of brain structure, activity and connectivity have also proven valuable; when measured non-invasively, identified changes in activity in the frontal lobe of the brain during the first year of life have served to predict an ASD diagnosis in infant siblings10. Because brain wavelengths vary, identifying and monitoring changes in the size of each different type of wavelength over the course of a year serves as valuable information in terms of not just determining an ASD diagnosis but also for further understanding brain fluctuations during that time period10.
Complementary to brain activity, previous studies from the Infant Brain Imaging Network (IBIS) revealed different approaches to more accurately predicting ASD diagnosis by using measurements of brain structure and connectivity, in addition to mathematical algorithms based on the shape and function of different brain regions, as potential predictors of a later diagnosis. This year, the analysis of early brain based ASD markers has afforded scientists more precision in determining an association with brain connectivity in critical ASD brain regions, as well as an insistence on sameness and stereotyped behaviors at 12 – 24 months11. Not only do these biological based markers aide in predicting later diagnosis and identifying features of ASD within a diagnosis, they have the potential to serve as objective ways to help determine specific interventions, both medical and behavioral.