The main aims of this study were to investigate if children with
high-functioning autism (HFA) and children with Tourette syndrome (TS) can
be differentiated in their executive functioning (EF) profile compared to
normal controls (NCs) and compared to each other and to investigate
whether children with HFA or children with TS and a comorbid group of
children with both disorders are distinct conditions in terms of EF. Four
groups of children participated in this study: HFA, TS, comorbid HFA + TS,
and a NC group. All children were in the age range of 6 to 13 years. The
groups were compared on five major domains of EF: inhibition, visual
working memory, planning, cognitive flexibility, and verbal fluency.
Children with HFA scored lower than NC children on all the EFs measured.
Children with TS and NC children showed the same EF profile. The HFA group
scored lower than the TS group for inhibition of a prepotent response and
cognitive flexibility. Children with HFA performed poorer than children
with comorbid HFA + TS on all functions, with the exception of inhibiting
an ongoing response, interference control, and verbal fluency. Children
with TS and children with comorbid HFA + TS could not be differentiated
from one another in terms of EF. This study indicates that EF deficits are
highly characteristic of children with HFA in comparison to children with
TS and NC. The results suggest that for the comparison between HFA and TS
groups, it is important to take into account comorbidity. A reevaluation
of the EF hypothesis in children with TS is suggested.We thank the children and parents without whose participation
this research would not have been possible.