Related Experiment Video
Updated: Nov 21, 2025

Use of a Video Scoring Anchor for Rapid Serial Assessment of Social Communication in Toddlers
Published on: March 14, 2018
General Cognitive Abilities and Psychosocial Development in Children and Adolescents Having a Co-Twin with Down
Gisa Aschersleben1, Katarzyna Hoffmann1, Wolfram Henn2
1Developmental Psychology Unit, Saarland University, Saarbrücken, Germany.
Objective:
To examine the general cognitive and psychosocial development in children and adolescents having a co-twin with Down syndrome.
Study Design:
A case control study with an individually matched control group was conducted. Participants included families with twins discordant for Down syndrome as well as with typically developing twins. The group of unaffected co-twins aged 4-16 years was compared with a control group of typically developing twins in terms of general cognitive abilities, behavioral problems, and prosocial behavior. The age and sex and the sex composition of the twins were individually matched. The Sijnders-Oomen nonverbal intelligence test was applied to assess children's IQ, and parents completed the Strength and Difficulties Questionnaire.
Results:
The unaffected co-twins did not differ from typically developing twins with respect to their IQ. Concerning the psychosocial development, significantly heightened values in unaffected co-twins twins were only obtained for the conduct problems scale (P = .01; r = 0.45), neither for the total difficulties score nor for the other behavioral problem scales significant differences were found.
Conclusions:
The general cognitive development of the unaffected co-twin of children with Down syndrome is not affected by the presence of their Down syndrome twin. Unaffected co-twins showed increased conduct problems, which is most pronounced in the younger children.
More Related Videos
Related Concept Videos
Cognitive Development During Adolescence
Information Processing Approach
Intellectual Disability
Autism Spectrum Disorder
These core symptoms manifest differently among individuals, ranging from mild to severe. The disorder's complexity extends beyond its clinical presentation, encompassing a diverse range of biological, cognitive, and sociocultural influences.
Language and Cognition
Introduction to Developmental Psychology

