Gender differences in parent-reported age at diagnosis of children with autism spectrum disorder

Background: Autism spectrum disorders (ASD) are more commonly observed in boys than in girls. There is growing awareness of ASD in girls and recognition that under-diagnosis is common. The current study aimed to investigate any evidence of reduction in the average age at diagnosis for girls by assessing whether: 1) girls' age at diagnosis has reduced, compared to boys', across two age cohorts - children born between 1996-1999 and 2002-2005; 2) age at diagnosis differed between boys and girls diagnosed across childhood; 3) any characteristics are associated with earlier age at diagnosis in girls. Methods: Data were available from large UK databases of children with ASD: The Database of Children with Autism Spectrum Disorder Living in the North East (http://daslne.org) and the Autism Spectrum Database-UK (www.asd-uk.com). Results: There was no differential reduction of parent-reported age at diagnosis for girls over time. For children receiving their diagnosis at age >= 60 months, boys received diagnoses an average of one year earlier than did girls (98.2 months, SD = 31.6 vs. 109.1 months, SD = 36.4). For boys and girls, earlier diagnosis was associated with toileting problems and temper problems. Having additional diagnoses (e.g., dyslexia, dyspraxia, and epilepsy) was associated with later diagnosis. Conclusions: Age at diagnosis has not decreased over time. Girls with ASD are diagnosed later than boys when aged 5 years or older. Health and education professionals would benefit from better understanding factors such as toileting problems, temper problems, and additional diagnoses that could potentially guide early identification of ASD in clinical practice for school-age girls.