Background. Previous studies have shown that individuals
with autism show impaired
performance on tests of executive function (Ozonoff et al. 1991, 1993;
Hughes & Russell, 1993;
Hughes et al. 1994). There is also strong evidence for genetic involvement
in autism (see Rutter,
1991 for review). If executive dysfunction is a core impairment in autism,
then similar
impairments are hypothesized to exist in a subtler form among the parents
of autistic children.
Methods. Forty parents of autistic children were compared with
40 parents of learning disabled
children and 36 adults from unaffected families on three computerized tests
of executive
function. These tasks tapped attentional-shifting skills, visuospatial
planning and working
memory. Participants also received a computerized control test of spatial
memory-span. In
addition, the interviewer's initial impressions of family members
were coded using a new 33-item
questionnaire.
Results. A significant proportion of parents of autistic children
(especially fathers) showed
impaired executive function. By contrast, parents did as well as both comparison
groups on a
control test of spatial span, and on other ‘non-executive’
measures from the tasks, indicating
that the autism group were as able and motivated as comparison groups.
Interestingly,
impairment of executive function was significantly correlated with the
interviewer's pre-test impression
of social abnormality among parents of autistic children.
Conclusions. The hypothesis that a significant proportion of
parents of autistic children show
impaired executive function was supported. Parents showed good memory ability,
but relatively
poor planning skills and attentional flexibility. The extent to which this
is an inherent trait in
family members, rather than a reflection of the difficulties involved in
caring for an autistic
child, remains to be examined.