Mapping geographical variation in the genetic and environmental aetiology of autism spectrum disorder and attention deficit hyperactivity disorder in Sweden

Observational studies suggest that the prevalence of autism spectrum disorder (ASD) risk varies geographically between urban and rural areas, with increased urbanicity associated with greater risk (1). In contrast, attention... [ view full abstract ]

Observational studies suggest that the prevalence of autism spectrum disorder (ASD) risk varies geographically between urban and rural areas, with increased urbanicity associated with greater risk (1). In contrast, attention deficit hyperactivity disorder (ADHD) has shown less evidence of urban-rural prevalence differences (1). We applied our spACE spatial analysis approach (2) to explore whether the genetic and environmental aetiology of these disorders varies in a similar way, using data from 8,612 twin pairs from the Swedish Twin Registry (3). Information on ASD and ADHD was collected using the A-TAC questionnaire administered via telephone interview with parents when the twins were either nine or twelve years old. Twin pairs were matched to Small Area Marketing Statistics (SAMS) locations by Statistics Sweden and we assigned the twin pairs to the centroids of these areas. By running a series of twin structural equation models in OpenMx while weighting the contribution of the twin pairs by the inverse of their distance from the point of estimation, we were able to produce maps of the variation in the genetic and environmental influences on ASD and ADHD. We will present these maps, and discuss their implications for our understanding of the aetiology of these disorders.

1. Vassos, E., Agerbo, E., Mors, O. & Pedersen, C. B. Urban-rural differences in incidence rates of psychiatric disorders in Denmark. Br J Psychiatry 208, 435–440 (2016).

2. Davis, O. S. P., Haworth, C. M. A., Lewis, C. M. & Plomin, R. Visual analysis of geocoded twin data puts nature and nurture on the map. Mol Psychiatr 17, 867–874 (2012).

3. Magnusson, P.K.E. et al. The Swedish Twin Registry: establishment of a biobank and other recent developments. Twin Res and Hum Genet, 16, 317-329 (2012).