Theory of Mind in children and adolescents with Down syndrome.

Introduction: To date, the evidence regarding False Belief (FB) abilities in individuals with Down syndrome (DS) has been both sparse and contradictory. Our study is the first systematic investigation targeting the relation between FB, mental age (MA), syntactic abilities (SA) and verbal short-term memory (VSTM) in individuals with DS so far.

Method: 27 German-speaking children/adolescents with DS (aged 10;0-20;1 years) completed a location-change FB-task and four standardized measures assessing nonverbal intelligence & MA, VSTM, receptive and productive SA.

Results: 37.5 % (n = 9) of our participants passed the FB-task, whereas 62.5 % (n = 15) did not answer the target question correctly. While no significant differences emerged for MA and language abilities in individuals who passed and those who failed FB-testing, VSTM came out as a significantly associated factor for FB-performance in a median split analysis of raw-scores.

Discussion: The results suggest that a substantial proportion of individuals with DS is impaired in FB-understanding. In contrast to previous findings on children with developmental disorders such as autism, developmental language deficit or hearing impairment, general and specific SA related to sentence complementation turned out to be of limited relevance for FB-understanding in individuals with DS.