Plasma oxytocin levels in relation to social and cognitive functioning in individuals with autism spectrum disorders

Date of Completion

January 2006


Psychology, Clinical




The autism spectrum disorders (ASDs) are characterized by significant impairments in social relatedness, which some have argued is at the core of the clinical presentation associated with the disorder. Recent research has suggested a link between the neuropeptide oxytocin and behaviors and traits rebated to affiliation and attachment. Studies investigating the potential role of oxytocin in ASDs have found lower levels of plasma OT (Modahl et al., 1998) and higher levels of the precursor to OT (Green et al., 2001) in children diagnosed with ASDs compared to typically developing children matched for age. In addition, levels of OT were inversely related to social and cognitive functioning in the children with ASD but not in the typically developing children. The present study was designed to replicate and expand upon the existing research in this area. Levels of plasma OT and its extended peptide form (OT-X) were explored in 44 individuals diagnosed with an ASD and 27 typically developing individuals. Results suggested that there was far greater variability in both OT and OT-X in the ASD compared to the control group. Independent samples t-tests revealed no significant between-group difference in levels of OT. However, there was a one-tailed trend (p=.06) toward a significantly higher level of OT-X in the ASD group. When outliers were excluded from statistical analyses, the ASD group had a significantly higher level of OT than the control group, but there was no significant between group difference in OT-X and variability continued to be significantly greater in the ASD group. Levels of OT and OT-X were negatively correlated with intellectual, adaptive, and social functioning in the ASD group. Potential implications and directions for future research are discussed.^