The Project RATSS

RATSS - The Roots of Autism Spectrum Disorder and ADHD

The study Roots of Autism and ADHD Twin Study in Sweden (RATSS) explore causal mechanisms for Autism Spectrum Disorder (ASD) and ADHD by examinations of discordant twin pairs.

Research shows that ASD and ADHD have biological causes, with complex genetic background components. However, recent studies also show that environmental factors might have a more important role in the etiology of these disorders than previously assumed. Still, the exact mechanisms and processes driving the phenotypes are unknown. Neither biological tests for diagnoses nor effective treatments are available.

The aim of the RATSS project is to do preclinical research to find new leads for ASD and ADHD etiology. The project is aiming to find biomarkers and to generate hypotheses that can be used to develop diagnostic tests and medical treatment options. The recruitment is focusing on twin pairs discordant for ASD or ADHD, i.e. one twin within a pair has an ADHD and/or ASD diagnosis while and the other twin do not. To rule out unspecific interpretations of the results, twin pairs typically developed, concordant for ASD and ADHD, and twin pairs with other neurodevelopmental disorders are included in the study. Since MZ twin pairs are genetically very similar, all differences in e.g. behavior, neurobiology, and (epi) genetics within the discordant pairs, can be informative for origin, diagnoses and the development of therapies, and might point to overseen non-shared environmental factors.

This research program is conducted at the Karolinska Institutet Center for Neurodevelopmental disorders (KIND) with Professor Sven Bölte being the principal investigator. Several other departments at KI, the Swedish Twin Registry and international collaborators are involved in the project. The RATSS is also a part of a larger European project called EU-AIMS.

The examinations of the twins are done at the clinical unit of KIND and at Karolinska Hospital in Solna. For more information about the examinations, please see our information booklet (in Swedish).


Research nurse

Anna Pilfalk

Mobil: 070 - 755 96 80

Division of Neuropsychiatry

Psychologist, PhD student

Karl Lundin


Division of Neuropsychiatry