Thursday, July 31, 2008

Autism and ADHD are not so different after all

More evidence that our current categorization of early onset cognitive disorders needs a rewrite.
Evidence for overlapping genetic influences on aut...[J Child Psychol Psychiatry. 2008] - PubMed Result

BACKGROUND: High levels of clinical comorbidity have been reported between autistic spectrum disorders (ASD) and attention deficit hyperactivity disorder (ADHD). This study takes an individual differences approach to determine the degree of phenotypic and aetiological overlap between autistic traits and ADHD behaviours in the general population.

METHODS: The Twins Early Development Study is a community sample born in England and Wales. Families with twins born in 1994-6 were invited to join; 6,771 families participated in the study when the twins were 8 years old. Parents completed the Childhood Asperger Syndrome Test and the Conners' DSM-IV subscales....

RESULTS: Significant correlations were found between autistic and ADHD traits in the general population (.54 for parent data, .51 for teacher data). In the bivariate models, all genetic correlations were >.50, indicating a moderate degree of overlap in genetic influences on autistic and ADHD traits...

CONCLUSIONS: These results suggest there are some common genetic influences operating across autistic traits and ADHD behaviours throughout normal variation and at the extreme. This is relevant for molecular genetic research, as well as for psychiatrists and psychologists, who may have assumed these two sets of behaviours are independent.
I suspect all clinicians with significant experience with autism are accustomed to children who have features of both ADHD and autism. So no surprises there. Unfortunately, most studies of ADHD or autism focus on "pure" subjects, so they exclude children who have features of both.

That means there's very little research about children with both ADHD and autism spectrum disorder -- we don't know what medications, behavioral or educational interventions are most effective.

These results may justify research on the large number of children and adults who aren't "pure" examples.

1 comment:

Mindsite said...

Interesting - I've often wondered about correlations/overlap here as well.