Sex differences in psychiatric diagnoses preceding autism diagnosis and their stability post autism diagnosis.

Abstract

Background: Autistic individuals often receive psychiatric diagnoses prior to their autism diagnosis. It remains unclear to what extent autistic females and males differ in their likelihood of receiving psychiatric diagnoses prior to their autism diagnosis and continue seeking care for them after an autism diagnosis.

Methods: In a nationwide cohort of all individuals born in Sweden 1990-2015 with a clinical autism diagnosis (N = 72,331, n_females = 24,110), we used linear and logistic regression to estimate the association between sex and (a) psychiatric diagnoses before autism diagnosis, including time trends by autism diagnosis year (2010-2020), (b) autism diagnosis age in those with preceding diagnoses, (c) stability of preceding diagnoses (defined as continued care utilization indicated through diagnosis or medication in the 5 years following autism diagnosis).

Results: In total 54.2% of autistic females and 40.9% of autistic males received at least one preceding psychiatric diagnosis (most common: ADHD, anxiety, depression). Autistic females showed higher odds than males for most preceding psychiatric diagnoses (OR_range = 1.29 [1.18, 1.41]-10.69 [8.06, 14.17]), except psychotic disorders (OR = 0.91 [0.78, 1.06]) and ADHD (OR = 0.69 [0.66, 0.71]). Sex differences in preceding diagnoses were persistent across different autism diagnosis years (2010-2020). For most conditions, females with a preceding diagnosis were diagnosed with autism later than males with the same condition. For both sexes, the stability of preceding diagnoses varied considerably (23.1%-88.9%) and was less than 50% for most diagnoses. Females showed a higher stability for anxiety, sleep disorders and self-harm (OR_range = 1.45 [1.30, 1.62]-2.37 [1.93, 2.90]), and males for psychotic disorders (OR = 0.60 [0.44, 0.81]).

Conclusions: Autistic females are more likely to be diagnosed with psychiatric conditions prior to an autism diagnosis and receive care for them post autism diagnosis. Our findings emphasize the variability of clinical presentation and importance of disentangling persistent support needs from overlapping diagnostic presentations, particularly in autistic females, to provide appropriate and timely care.