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Autistic-like traits

Lundström, Sebastian LU (2011) In Lund University, Faculty of Medicine Doctoral Dissertation Series 2011:48.
Abstract
Introduction

Autism spectrum disorders (ASDs) are neurodevelopmental disorders characterized by restrictions in social interaction, understanding, and communication, by stereotyped patterns of repetitive behaviors, and by narrow interests. ASDs, which affect about 1% of the population, are predominantly genetic, but no single explanation has been found.

On the contrary, a multitude of developmental trajectories are possible. In relatives of individuals with ASDs, autistic-like traits (ALTs, i.e. traits that are less pronounced than, but qualitatively similar to, ASD symptoms) occur more frequently than expected by chance. When studied in the general population, ALTs have shown high internal consistency, dimensional... (More)
Introduction

Autism spectrum disorders (ASDs) are neurodevelopmental disorders characterized by restrictions in social interaction, understanding, and communication, by stereotyped patterns of repetitive behaviors, and by narrow interests. ASDs, which affect about 1% of the population, are predominantly genetic, but no single explanation has been found.

On the contrary, a multitude of developmental trajectories are possible. In relatives of individuals with ASDs, autistic-like traits (ALTs, i.e. traits that are less pronounced than, but qualitatively similar to, ASD symptoms) occur more frequently than expected by chance. When studied in the general population, ALTs have shown high internal consistency, dimensional distributions, and hereditary influence. It is, however, unclear if ASDs are the extreme end of a continuum of ALTs, if ALTs are psychiatrically relevant, and if ALTs share etiological factors with ASDs.



Methods

This thesis employs three nation-wide twin studies to pursue the following aims:

1. To establish the distribution of ALTs and provide estimates of the genetic and

environmental effects involved.

2. To describe the relationships between ALTs and other types of mental problems,

including shared etiology.

3. To clarify whether ALTs are influenced by increasing paternal age, which is a known

risk factor for ASDs.

4. To determine whether there is a demarcation in the genetic effects between ASDs

and ALTs.



Results

1. ALTs are dimensionally distributed in 46% of all 9- and 12-year-old twins, and genetic effects account for 68% of the variation in ALTs.

2. Increasing levels of ALTs are related to an increased risk of concomitant mental health problems in both adults and children. In addition, common genetic and environmental etiological factors were found behind ALTs and phenotypically different mental health problems.

3. Increasing paternal age increases the risk for ALTs and ASDs alike.

4. No demarcation could be discerned between the genetic effects on ASDs and ALTs, implying a continuum from ASDs to ALTs predominantly affected by genes.



Conclusion

Taken together, the results of this thesis suggest that ASDs can be viewed as the extreme end of ALTs, or that ALTs are truly a ‘shadow’ of ASDs in persons with sub-threshold problems with social interaction, communication, and behavioral flexibility, and that

ALTs may be crucial for understanding mental health problems and for scientific attempts to identify etiological factors behind ASDs. (Less)
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author
supervisor
opponent
  • Professor Bilenberg, Niels, Institute of Clinical Research, University of Southern Denmark
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Autism, twin, genetics, Autistic-like traits
in
Lund University, Faculty of Medicine Doctoral Dissertation Series
volume
2011:48
pages
103 pages
publisher
Department of Clinical Sciences, Lund University
defense location
Lilla Aulan, MFC, SUS
defense date
2011-05-20 13:00
ISSN
1652-8220
ISBN
978-91-86671-96-9
language
English
LU publication?
yes
id
9bd37ef1-2b3c-4786-aa3b-5ab6e531dacd (old id 1897931)
date added to LUP
2011-05-04 08:36:49
date last changed
2016-09-19 08:44:48
@phdthesis{9bd37ef1-2b3c-4786-aa3b-5ab6e531dacd,
  abstract     = {Introduction<br/><br>
Autism spectrum disorders (ASDs) are neurodevelopmental disorders characterized by restrictions in social interaction, understanding, and communication, by stereotyped patterns of repetitive behaviors, and by narrow interests. ASDs, which affect about 1% of the population, are predominantly genetic, but no single explanation has been found.<br/><br>
On the contrary, a multitude of developmental trajectories are possible. In relatives of individuals with ASDs, autistic-like traits (ALTs, i.e. traits that are less pronounced than, but qualitatively similar to, ASD symptoms) occur more frequently than expected by chance. When studied in the general population, ALTs have shown high internal consistency, dimensional distributions, and hereditary influence. It is, however, unclear if ASDs are the extreme end of a continuum of ALTs, if ALTs are psychiatrically relevant, and if ALTs share etiological factors with ASDs.<br/><br>
<br/><br>
Methods<br/><br>
This thesis employs three nation-wide twin studies to pursue the following aims:<br/><br>
1. To establish the distribution of ALTs and provide estimates of the genetic and<br/><br>
environmental effects involved.<br/><br>
2. To describe the relationships between ALTs and other types of mental problems,<br/><br>
including shared etiology.<br/><br>
3. To clarify whether ALTs are influenced by increasing paternal age, which is a known<br/><br>
risk factor for ASDs.<br/><br>
4. To determine whether there is a demarcation in the genetic effects between ASDs<br/><br>
and ALTs.<br/><br>
<br/><br>
Results<br/><br>
1. ALTs are dimensionally distributed in 46% of all 9- and 12-year-old twins, and genetic effects account for 68% of the variation in ALTs.<br/><br>
2. Increasing levels of ALTs are related to an increased risk of concomitant mental health problems in both adults and children. In addition, common genetic and environmental etiological factors were found behind ALTs and phenotypically different mental health problems.<br/><br>
3. Increasing paternal age increases the risk for ALTs and ASDs alike.<br/><br>
4. No demarcation could be discerned between the genetic effects on ASDs and ALTs, implying a continuum from ASDs to ALTs predominantly affected by genes.<br/><br>
<br/><br>
Conclusion<br/><br>
Taken together, the results of this thesis suggest that ASDs can be viewed as the extreme end of ALTs, or that ALTs are truly a ‘shadow’ of ASDs in persons with sub-threshold problems with social interaction, communication, and behavioral flexibility, and that<br/><br>
ALTs may be crucial for understanding mental health problems and for scientific attempts to identify etiological factors behind ASDs.},
  author       = {Lundström, Sebastian},
  isbn         = {978-91-86671-96-9},
  issn         = {1652-8220},
  keyword      = {Autism,twin,genetics,Autistic-like traits},
  language     = {eng},
  pages        = {103},
  publisher    = {Department of Clinical Sciences, Lund University},
  school       = {Lund University},
  series       = {Lund University, Faculty of Medicine Doctoral Dissertation Series},
  title        = {Autistic-like traits},
  volume       = {2011:48},
  year         = {2011},
}