Brief report: Autism spectrum disorder diagnostic persistence in a 10-year longitudinal study

Background: The aim was to examine diagnostic persistence of Autism Spectrum Disorder (ASD) in individuals without intellectual disability from childhood to emerging adulthood. Method: We assessed 38 children with estimated full-scale intelligence quotient (IQ) >70 who were diagnosed with ASD at baseline (Mage=12.0, SD=2.3, 84% male), and re-assessed two (n=37, Mage=14.2, SD=2.4, 84% male) and 10 years (n=23, Mage=21.7, SD=2.4, 78% male) later. Results: At two-year follow-up, all participants still met diagnostic criteria for ASD according to the Diagnostic and Statistical Manual for Mental Disorders – fourth version (DSM-IV). At 10-year follow-up, 65% met diagnostic criteria for ASD according to DSM-IV, 48% met diagnostic criteria according to the Diagnostic and Statistical Manual for Mental Disorders – fifth version (DSM-5), 57% met the ASD cut-off on the Autism Spectrum Quotient 10-item (AQ-10), and 78% met either DSM-IV criteria or cut-off on the AQ-10. Higher IQ in childhood predicted loss of ASD diagnosis according to DSM-IV criteria (Hedges g = 1.30). A higher proportion of girls compared to boys displayed loss of ASD diagnosis according to DSM-IV criteria. Conclusions: These findings suggest that ASD traits among individuals without intellectual disability may wane into emerging adulthood and that loss of ASD diagnosis is associated with higher IQ and being a girl. Diagnostic re-evaluations may be warranted for some individuals diagnosed with ASD as children or adolescents