UNFOLDING AUTISM AND ADHD: CONVERGENT AND DIVERGENT PATHWAYS IN INFANTS AT RISK
Autism and Attention-Deficit/Hyperactivity Disorder (ADHD) are prevalent developmental conditions, associated with individual burden and substantial societal costs. No cure is available and progress in intervention research is hampered by poor etiological insight. We propose that the discipline of developmental psychology is in a unique position to change this situation. The reason for this is that it can define processes early in life that precede the emergence of symptoms, and hence reveal targets for future early intervention. In this program, we will study high risk infant cohorts (siblings of children with autism and ADHD) to test the hypothesis that in addition to condition-specific early signs, attentional impairment constitutes a condition-general risk marker in infancy. We will combine the familial-risk approach with a study of infant twins, in order to map the contribution of genetic and environmental factors to differences in infant behaviors associated with risk for later autism or ADHD. The program spans across the humanities and social sciences, medicine and health as well as engineering sciences, and includes experts from several Swedish and foreign universities. It is ambitious, but because it builds on and expands ongoing projects and infrastructure, it is fully feasible. The program will inform psychological theories of early normal and abnormal development and facilitate early screening and intervention.
Final report
The project’s focus and development.
Autism and Attention-Deficit/Hyperactivity Disorder (ADHD) are common developmental disorders. Lack of knowledge regarding causes and early development is a challenge for treatment research. The goal of the project has been to shed light on processes that precede the behavioral symptoms, and can thereby pave the way for early targeted treatment interventions. A focus of the study is on advanced and child-friendly methods such as eye tracking (measurement of infants’ gaze behavior) and electroencephalography (EEG; measurement of brain activity). At the same time, we have measured more qualitative aspects, such as parent-child interaction, and clinical measures, namely symptoms of autism and ADHD. The project’s development has largely followed the plan described in the application, and has already led to several important findings and scientific publications, including in leading journals such as Nature Communications and Biological Psychiatry.
Briefly about implementation.
In accordance with the application, the work has been divided into three parts:
1. A longitudinal study of infant twins. The purpose of this has been to create a normative database with which we can compare the results from clinical groups, and to assess the significance of genetic and environmental factors through behavioral genetic analyses for any differences in various behaviors/phenotypes. This study is unique in its kind. We have also created an application that collects eye tracking data through private iPads, and have conducted a study that has validated this method on infants.
2. A longitudinal study of infants whose siblings have autism or ADHD. The purpose of this has been to map early developmental processes that prelude diagnoses/symptoms later in childhood.
3. A follow-up study of a previous infant cohort, which we have tested within the framework of this RJ project, at the age of 6 years. The purpose of this is to examine the stability of early diagnoses, such as autism and ADHD, over preschool age.
All parts have been carried out according to plan, although the Covid19 pandemic has caused some delays during these last two years. We have, in total, completed testing on more than 1000 children within the scope of the project, and each child has usually participated in a number of different examination opportunities. Therefore, a significant database has been built up which can be used in the future for various types of analyses and follow-ups. The first years were focused on recruiting staff and participants, the ethics application, and practical preparations. Later in the project, the focus has shifted to more analyzing and reporting, and this phase will continue for several more years based on the generated data.
The project’s three most important results.
Parts of the project’s important results have not yet been published; here we focus on what has already been published:
1. A deeper understanding of the developmental processes that prelude an autism diagnosis. We have been able to show in several publications that children who later receive an autism diagnosis already in infancy process sensory stimuli in a different way compared to other children. They seem to be more sensitive to both light (Nyström et al 2018) and sound (Rudling et al 2021) in combination with difficulties in perceiving the temporal connections between information from various senses (Falck-Ytter et al, 2018). These findings suggest that although autism is defined by symptoms in the field of social communication, the earliest signs of autism are not specifically tied to social functions but seem to relate to basic attention/perception.
2. It is possible to complete large-scale twin studies of infants using eye-tracking and EEG method (Falck-Ytter et al 2021), and this type of data can lead to completely new results and issues (Portugal et al 2022). For example, we have shown that individual differences in infant pupil size largely reflects genetic variation, and is correlated with risk for psychiatric diagnoses that appear much later in life (Portugal et al 2022). The twin study leads the path to completely new questions/analyses of relevance for our understanding of typical and atypical development.
3. Deepened understanding of the similarities and differences between signs of autism and ADHD during infancy, in terms of attentional functions and temperamental traits (Hendry et al 2020; Konke et al 2021). These findings may be of importance for future treatment research regarding each diagnosis, for example, to what extent it is necessary to differentiate between different diagnoses when developing strategies for early intervention.
New research questions.
The project has led to new research questions, for example:
1. How do problems with attention and perception during early infancy relate to later problems with social communication (symptoms of autism)? What developmental events can explain this relationship? We are working actively on this question and will use this to form the basis for future grant applications.
2. What significance does the difference in infant gut microbiome play in brain development and behavior? This issue is now being studied within the framework of an interdisciplinary research environment grant funded by VR.
How the project has spread research and results, and if and how collaboration has taken place.
The results have been spread primarily through publication in scientific journals with Open Access (see separate publication list). We have also presented the study/results at international and national conferences (e.g. Autism Winter Days, Yväskylä (2016), Congress of the European Society of Child Neurolody, Lugano (2016), SIKON, Odense (2016), Attention-Riks, Stockholm (2016), ASFAR, Perth (2016), Autismus Deutschland Dortmund (2017), International Summit and Conference Behavior Analysis and Autism in Higher Education, Stockholm (2018), Swedish Physiotherapy Meeting, Stockholm (2018), EUNETHYDIS, Edinburgh (2018), NordCAP, Turku (2018), Autism Germany ICF Conference, Stuttgart (2018), Meeting of Minds, Copenhagen (2018), EUNETHYDIS, Lisbon (2019), Aktiv & Ung, Bergen (2019), Autism Europe (2019), Focus on Autism and other NPF, Stockholm (2019), Swiss Pediatric Society, Bellinzona (2019), Swedish Child and Adolescent Psychiatry Annual Meeting, Stockholm (2020), International Society for Autism Research, Seattle (2020), Behavior Genetics Annual Meeting, virtual meeting (2021), International Congress on Twin Studies, Budapest (2021)), as well as through interaction with other stakeholders (via social media, training opportunities for clinics, etc.). Regarding the latter, we have had several collaborations with the Autism Center for Young Children and the ADHD Center in Stockholm, both to stimulate recruitment to the study and facilitate the knowledge exchange between researchers and clinics. We also have regular communication with the parents of children with autism/ADHD, mainly through our Facebook page.
Autism and Attention-Deficit/Hyperactivity Disorder (ADHD) are common developmental disorders. Lack of knowledge regarding causes and early development is a challenge for treatment research. The goal of the project has been to shed light on processes that precede the behavioral symptoms, and can thereby pave the way for early targeted treatment interventions. A focus of the study is on advanced and child-friendly methods such as eye tracking (measurement of infants’ gaze behavior) and electroencephalography (EEG; measurement of brain activity). At the same time, we have measured more qualitative aspects, such as parent-child interaction, and clinical measures, namely symptoms of autism and ADHD. The project’s development has largely followed the plan described in the application, and has already led to several important findings and scientific publications, including in leading journals such as Nature Communications and Biological Psychiatry.
Briefly about implementation.
In accordance with the application, the work has been divided into three parts:
1. A longitudinal study of infant twins. The purpose of this has been to create a normative database with which we can compare the results from clinical groups, and to assess the significance of genetic and environmental factors through behavioral genetic analyses for any differences in various behaviors/phenotypes. This study is unique in its kind. We have also created an application that collects eye tracking data through private iPads, and have conducted a study that has validated this method on infants.
2. A longitudinal study of infants whose siblings have autism or ADHD. The purpose of this has been to map early developmental processes that prelude diagnoses/symptoms later in childhood.
3. A follow-up study of a previous infant cohort, which we have tested within the framework of this RJ project, at the age of 6 years. The purpose of this is to examine the stability of early diagnoses, such as autism and ADHD, over preschool age.
All parts have been carried out according to plan, although the Covid19 pandemic has caused some delays during these last two years. We have, in total, completed testing on more than 1000 children within the scope of the project, and each child has usually participated in a number of different examination opportunities. Therefore, a significant database has been built up which can be used in the future for various types of analyses and follow-ups. The first years were focused on recruiting staff and participants, the ethics application, and practical preparations. Later in the project, the focus has shifted to more analyzing and reporting, and this phase will continue for several more years based on the generated data.
The project’s three most important results.
Parts of the project’s important results have not yet been published; here we focus on what has already been published:
1. A deeper understanding of the developmental processes that prelude an autism diagnosis. We have been able to show in several publications that children who later receive an autism diagnosis already in infancy process sensory stimuli in a different way compared to other children. They seem to be more sensitive to both light (Nyström et al 2018) and sound (Rudling et al 2021) in combination with difficulties in perceiving the temporal connections between information from various senses (Falck-Ytter et al, 2018). These findings suggest that although autism is defined by symptoms in the field of social communication, the earliest signs of autism are not specifically tied to social functions but seem to relate to basic attention/perception.
2. It is possible to complete large-scale twin studies of infants using eye-tracking and EEG method (Falck-Ytter et al 2021), and this type of data can lead to completely new results and issues (Portugal et al 2022). For example, we have shown that individual differences in infant pupil size largely reflects genetic variation, and is correlated with risk for psychiatric diagnoses that appear much later in life (Portugal et al 2022). The twin study leads the path to completely new questions/analyses of relevance for our understanding of typical and atypical development.
3. Deepened understanding of the similarities and differences between signs of autism and ADHD during infancy, in terms of attentional functions and temperamental traits (Hendry et al 2020; Konke et al 2021). These findings may be of importance for future treatment research regarding each diagnosis, for example, to what extent it is necessary to differentiate between different diagnoses when developing strategies for early intervention.
New research questions.
The project has led to new research questions, for example:
1. How do problems with attention and perception during early infancy relate to later problems with social communication (symptoms of autism)? What developmental events can explain this relationship? We are working actively on this question and will use this to form the basis for future grant applications.
2. What significance does the difference in infant gut microbiome play in brain development and behavior? This issue is now being studied within the framework of an interdisciplinary research environment grant funded by VR.
How the project has spread research and results, and if and how collaboration has taken place.
The results have been spread primarily through publication in scientific journals with Open Access (see separate publication list). We have also presented the study/results at international and national conferences (e.g. Autism Winter Days, Yväskylä (2016), Congress of the European Society of Child Neurolody, Lugano (2016), SIKON, Odense (2016), Attention-Riks, Stockholm (2016), ASFAR, Perth (2016), Autismus Deutschland Dortmund (2017), International Summit and Conference Behavior Analysis and Autism in Higher Education, Stockholm (2018), Swedish Physiotherapy Meeting, Stockholm (2018), EUNETHYDIS, Edinburgh (2018), NordCAP, Turku (2018), Autism Germany ICF Conference, Stuttgart (2018), Meeting of Minds, Copenhagen (2018), EUNETHYDIS, Lisbon (2019), Aktiv & Ung, Bergen (2019), Autism Europe (2019), Focus on Autism and other NPF, Stockholm (2019), Swiss Pediatric Society, Bellinzona (2019), Swedish Child and Adolescent Psychiatry Annual Meeting, Stockholm (2020), International Society for Autism Research, Seattle (2020), Behavior Genetics Annual Meeting, virtual meeting (2021), International Congress on Twin Studies, Budapest (2021)), as well as through interaction with other stakeholders (via social media, training opportunities for clinics, etc.). Regarding the latter, we have had several collaborations with the Autism Center for Young Children and the ADHD Center in Stockholm, both to stimulate recruitment to the study and facilitate the knowledge exchange between researchers and clinics. We also have regular communication with the parents of children with autism/ADHD, mainly through our Facebook page.