Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by deficits in social communication and restricted, repetitive behaviour. Symptoms arise in the first years of life and, although treatment often improves functioning and daily living, ASD is generally a life-long disorder, and can be very disabling and cause significant economic costs for society.

Although ASD affects 1-2 % of children, it is still relatively rare compared to more common chronic child health conditions like asthma or obesity. Therefore, large, population-based studies with complete information on pregnancy and early life are needed in order to accurately identify important risk factors and discover the causes of ASD. Large, population-based studies with complete longitudinal information are also needed to better understand the life course of persons with ASD in order to develop interventions and improve quality of life.

NCRR has the data resources to make important and unique contributions to epidemiological research in ASD. Examples of research focusing on ASD specifically include work on family and pregnancy risk factors, such as parental age and occupational exposures during pregnancy, obstetric, pregnancy and new-born complications, family medical history and urbanity at birth or through childhood. Studies of ASD along with other severe mental disorders include contrasting time trends in incidence, risk factors such as parental age, antidepressant use in pregnancy and family history of related disorders.

Both genetic and non-genetic environmental factors, like maternal illness during pregnancy, are important contributors to ASD. It is likely that the interplay between genetics and environmental factors during critical periods of development is a key factor. Future investigations of ASD will need to combine genetic and environmental factors in the same studies. NCRR houses the largest assembly of genetic, biological and longitudinal data on persons with ASD in the world. Therefore, NCRR will be a crucial partner in ASD etiologic studies in the years to come.

Currently, NCRR is involved in projects that examine questions like:

• How do genes influence the risk for ASD from exposures like traffic-related air pollution? Are risk patterns different or the same for ASD and ADHD?
• Is risk for ASD influenced by environmental factors during pregnancy that can change the ways genes are expressed?
• Are there any significant gene-environment interactions in the risk of ASD from pregnancy conditions like maternal smoking or diabetes?
• What is the overlap between genes increasing risk for ASD and disorders like schizophrenia and ADHD? Do any shared genes belong to a biologic pathway that sheds light on shared causes across these disorders?

For further reading

Singer AB, et al. (2017) ”Parental exposure to occupational asthmagens and risk of autism spectrum disorder in a Danish population-based case-control study.” Environmental Health: https://doi.org/10.1186/s12940-017-0230-8

St Pourcain B., et al (2017) “ASD and schizophrenia show distinct developmental profiles in common genetic overlap with population-based social communication difficulties.” Mol Psychiatry: 10.1038/mp.2016.198

Robinson, E. B., et al (2016) “Genetic risk for autism spectrum disorders and neuropsychiatric variation on the general population.” Nat Genet: 10.1038/ng.3529

Schendel DE., et al (2016) “”Association of psychiatric and neurologic comorbidity with mortality among persons with autism spectrum disorder in a Danish Population.” Jama Pediatrics: 10.1001/jamapediatrics.2015.3935

Christensen J et al. (2016) “Risk of epilepsy and autism in full- and half-siblings – a population-based cohort study.” Epilepsia: 10.1111/epi.13595

Sandin S, et al. (2015) “A. Autism risk associated with parental age and with increasing difference in age between the parents.” Molecular Psychiatry: 10.1038/mp.2015.70

Hansen, S. N., Schendel D.E. and Parmer E.T. (2015)” Explaining the increase in the prevalence of autism spectrum disorders: the proportion attributable to changes in reporting practices”. Jama Pediatrics: 10.1001/jamapediatrics.2014.1893

Atladottir HO, et al (2014)” The increasing prevalence of reported diagnoses of childhood psychiatric disorders: a descriptive multinational comparison.” Eur Child Adoles Psychiatry: 10.1007/s00787-014-0553-8

Christensen J, et al (2013) “Prenatal valproate exposure and risk of autism spectrum disorders and childhood autism – a population-based study.” JAMA Pediatrics: 10.1001/jama.2013.2270

Grønborg TK, et al (2013) “The recurrence of autism spectrum disorders in Danish families: a population-based cohort study.” Jama Pediatrics: 10.1001/jamapediatrics.2013.2259