The EU-AIMS Longitudinal European Autism Project (LEAP): Clinical characterisation

Tony Charman, Eva Loth, Julian Tillmann, Daisy Crawley , Caroline Wooldridge, David Goyard, Jumana Ahmad, Bonnie Auyeung, Sara Ambrosino, Tobias Banaschewski, Simon Baron-Cohen, Sarah Baumeister, Christian Beckmann, Sven Bölte, Thomas Bourgeron, Carsten Bours, Michael Brammer, Daniel Brandeis, Claudia Brogna, Yvette de BruijnBhismadev Chakrabarti, Ineke Cornelissen, Flavio Dell’ Acqua, Guillaume Dumas, Sarah Durston, Christine Ecker, Jessica Faulkner, Vincent Frouin, Pilar Garces, Lindsay Ham, Hannah Hayward, Joerg Hipp, Rosemary J. Holt, Johan Isaksson, Mark H. Johnson, Emily J H Jones , Prantik Kundu, Meng-Chuan Lai, Xavier Liogier D’ardhuy, Michael V. Lombardo, David J Lythgoe, René Mandl, Luke Mason, Andreas Meyer-Lindenberg, Carolin Moessnang, Nico Mueller, Laurence O’Dwyer, Marianne Oldehinkel , Bob Oranje, Gahan Pandina, Antonio M Persico, Barbara Ruggeri, Amber N. V. Ruigrok, Jessica Sabet, Roberto Sacco, Antonia San Jóse Cacéres , Emily Simonoff, Roberto Toro, Heike Tost, Jack Waldman, Steve C R Williams, Marcel P Zwiers, Will Spooren, Declan G M Murphy, Jan K Buitelaar

Research output: Contribution to journalArticlepeer-review


The EU-AIMS Longitudinal European Autism Project (LEAP) is the to-date largest multi-centre, multi-disciplinary observational study on biomarkers for autism spectrum disorder (ASD). The current paper describes the clinical characteristics of the LEAP cohort and examines age, sex and IQ differences in ASD and common co-occurring psychiatric symptoms. A companion paper describes the overall design and experimental protocol and outlines the strategy to identify stratification biomarkers (Loth et al., under review).

Methods: From six research centres in four European countries we recruited 437 children and adults with ASD and 300 controls between the ages of 6 and 30 years with IQs varying between 50 and 148. We conducted in-depth clinical phenotyping including IQ and a wide range of observational, interview and questionnaire measures of the ASD phenotype, as well as co-occurring psychiatric symptoms. We examined whether there are sex, age, and IQ differences in the severity of ASD symptoms and co-occurring psychiatric symptoms.

Results: The cohort showed heterogeneity in ASD symptom presentation, with only minimal to moderate site differences on core clinical and cognitive measures. On both interview and observational measures, ASD symptom severity was lower in adults compared to children and adolescents. The precise pattern of differences varied across measures but there was some evidence of both lower social symptoms and lower repetitive behaviour severity in adults. Males had higher ASD symptom scores than females on clinician-rated but not on parent-reported dimensional measures of ASD symptoms. In contrast, self-reported ASD symptom severity was higher in adults compared to adolescents, and in females than males (in adults only). Scores on ASD symptom measures were moderately negatively associated with IQ. Males with ASD had higher levels of Inattentive ADHD symptoms than females and both Inattentive and Hyperactive/Impulsive ADHD symptoms were lower in adults than children and adolescents.

Conclusions: The well-established phenotypic heterogeneity in ASD is well captured in the LEAP cohort. Variation both in core ASD symptom severity and in commonly co-occurring psychiatric symptoms were systematically associated with sex, age, IQ – and whether clinician, parent or self-reported. The accelerated longitudinal design of the LEAP cohort will enable us to track trajectories of the ASD phenotype and co-occurring conditions over development and relate these to the wide range of candidate biomarkers also tested in the sample.
Original languageEnglish
Pages (from-to)1-21
Number of pages21
JournalMolecular Autism
Issue number27
Early online date23 Jun 2017
Publication statusE-pub ahead of print - 23 Jun 2017


  • autism
  • autism spectrum disorder
  • phenotype
  • behaviours
  • heterogeneity
  • sex
  • age
  • IQ


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