Time is of the essence: Age at autism diagnosis, sex assigned at birth, and psychopathology
Authors: Smith Jessica V , McQuaid Goldie A , Wallace Gregory L , Neuhaus Emily , Lopez Andrea , Ratto Allison B , Jack Allison , Khuu Alexis , Webb Sara J , Verbalis Alyssa , Pelphrey Kevin A , Kenworthy Lauren 
Published: May 2024

Age at autism diagnosis is associated with sex assigned at birth (hereafter, “sex”), such that girls/women are more likely to be delayed or “missed” entirely in the diagnostic process compared to boys/men. Later diagnosed individuals, especially girls/women, demonstrate increased anxious/depressive symptoms. Data on autistic youth from clinic-based ( n = 1035; 22.9% assigned female) and sex-balanced research-based ( n = 128; 43% assigned female) samples were probed via regression-based mediation models to understand relationships between diagnostic age, sex, and symptoms of anxiety/depression. We hypothesized diagnostic age would mediate the relationship between sex and anxious/depressive symptoms. In both samples, later diagnostic age predicted greater anxious and depressive symptoms, and sex did not directly predict anxious symptoms. In the clinic-based but not the research-based sample, individuals assigned female at birth were later diagnosed than those assigned male, and there was a significant indirect effect of sex on anxious and depressive symptoms through diagnostic age, such that those assigned female and later diagnosed experienced greater symptoms. Within the research-based sample only, sex predicted depressive symptoms. The present study provides an important impetus for further evaluating the implications of diagnostic timing, enhancing tools for recognizing autism in individuals assigned female at birth, and grounding research with real-world ascertainment strategies. Lay Abstract Previous research has shown that girls/women are diagnosed later than boys/men with autism. Individuals who are diagnosed later in life, especially girls/women, have greater anxious and depressive symptoms. Previous research has been limited due to narrow inclusionary criteria for enrollment in studies. The present study uses two samples—one clinic-based, large “real-world” sample and another research-based sample with strict criteria for autism diagnosis—to understand the relationships between diagnostic age, sex assigned at birth, and symptoms of anxiety/depression. In both samples, those who were diagnosed later had greater anxious/depressive symptoms, and anxiety was not predicted by sex. In the clinic-based but not research-based sample, those assigned female at birth were diagnosed later than those assigned male at birth. In the clinic-based sample only, individuals assigned female at birth and who were later diagnosed experienced greater symptoms of anxiety/depression compared to those assigned male who benefited from earlier diagnostic timing. Within the research-based sample, those assigned female at birth had greater depressive symptoms than those assigned male. These findings highlight the importance of timely identification of autism, especially for girls/women who are often diagnosed later. Community-based samples are needed to better understand real-world sex-based and diagnostic age-based disparities in mental health.