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Title: Adolescent autistic traits and internalising traits : quantitative genetic investigations of co-occurrence patterns
Author: Scherff, Aline D.
ISNI:       0000 0004 5357 6185
Awarding Body: Birkbeck (University of London)
Current Institution: Birkbeck (University of London)
Date of Award: 2014
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Autism spectrum disorders (ASD) are characterised by social-communication difficulties and non-social symptoms such as restricted and repetitive behaviours and interests. ASD characteristics can be investigated at the subclinical trait level within the general population, and these quantitative autistic traits have been shown to have a smooth distribution. Adolescence is an important developmental stage, particularly for the emergence of internalising problems. However, few studies to date have investigated the causes of co-occurring autistic traits and internalising traits during adolescence. The aim of this thesis is to explore the aetiological causes of this trait association between the ages of 12 to 16 years using a quantitative genetic approach. This thesis employs a classic twin design and the sample came from the Twins Early Development Study (TEDS). The causes of the association between autistic and internalising traits in early adolescence are the first focus of this thesis. The analyses in Chapter 4 explore this aetiological association at ages 12-14 years, revealing a moderate phenotypic trait association and at the aetiological level moderate genetic overlap, substantial shared environmental and modest nonshared environmental overlap. Teasing apart these associations further, Chapter 5 identifies specific autistic-like behaviours by means of factor analysis. Relating these factor-derived autistic trait subdomains to the internalising trait measure demonstrated distinguishable patterns of phenotypic and aetiological associations. A factor named autistic-like ‘Social Unease’ showed the most phenotypic and genetic overlap with internalising traits. Secondly, this thesis investigates in Chapter 6 the role of childhood nonshared environment on internalising and autistic traits in early adolescence using the monozygotic twin differences design. Analyses showed that birth weight, childhood hyperactivity and peer problems played a role, via the nonshared environment, in influencing individual differences in internalising and autistic traits in early adolescence. Finally, Chapter 7 presents findings on later adolescence, at age 16 years, exploring the association of autistic traits with anxiety traits and depression traits separately and drawing on both parent and self ratings. The implications of these findings, their limitations and their contribution to the current literature are considered in the Discussion (Chapter 8).
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available