Impact of Family History of Depression on Cognitive Ability and Symptom Severity in Autism

Background: A link has been found between autism spectrum disorders and an increased amount of familial mood disorders.  Moreover, in an as yet unexplained set of findings, a possible link exists between familial depression and increased cognitive ability in autism.   

Objectives: The purpose of this study, in addition to replicating previous studies in a larger sample, will be to examine the possible explanations for the link between depression in families and increased cognitive abilities in autism by investigating the correlation between specific diagnosis on the autism spectrum (autistic disorder vs. Aspergers vs. PDD) and familial depression,  as well as between symptom severity and familial depression.   

Methods: Archival data collected in the course of clinical diagnostic evaluations for individuals diagnosed with an autism spectrum disorder will be examined. 

Results: Pilot data has been analyzed.  An ANOVA revealed a trend for IQ being higher in the group with a family history of depression, approaching significance, F(1,24) = 3.50, p=0.074.  Further analysis showed that the participants were equally represented each autism spectrum disorder, and that there was no significant difference in symptom severity  of those with and without familial history. 

Conclusions: Pilot analyses support previous findings of higher  mean IQ for participants with an ASD who have a family history of depression than for those without.  The results also imply that the difference in IQ cannot be attributed to differences in group membership and symptom severity.