Changes in Characteristics Associated With ADHD and ASD Diagnoses Over Time.

From 2012–2022 in Danish registry data, prediagnostic risk profiles for ADHD and ASD attenuated toward controls, with low birth weight OR dropping from 1.54 to 1.17.

• Why it matters: Rising ADHD and ASD diagnoses may reflect shifts in diagnostic practices, but it was unclear whether links between prediagnostic characteristics and later diagnoses changed over time.
• What they did: In a nationwide matched case-control design, cases diagnosed before age 18 (2012–2022) were matched 1:10 to controls without ADHD/ASD by sex, birth year, municipality, and country of birth, using conditional logistic regression across diagnosis years.
• The result: Associations differed across all 19 characteristics but weakened over time, especially for socioeconomic and perinatal factors, with greater attenuation for ADHD than ASD and more pronounced effects for diagnoses at ages 10–17.

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