Cross-sectional analysis finds age-related measurement bias in ADHD screening tool across adulthood

This cross-sectional analysis examined age-related measurement bias in the 18-item Adult ADHD Self-Report Scale (ASRS) across adulthood. The study included 600 adults, with 100 participants per decade from ages 20 to 80. The primary outcome was Differential Item Functioning (DIF), which assesses whether items function differently across groups (here, age) at equivalent levels of the latent trait (ADHD severity). The analysis found that 5 of the 18 items exhibited significant uniform DIF, indicating measurement bias. Latent ADHD trait scores showed high reliability (ωH = .895). Regarding symptom patterns, older adults were less likely to endorse hyperactivity symptoms in the ASRS Part A. Specifically, Part A scores decreased by 1.36 points from ages 20 to 80, or approximately 0.27 points per decade. Conversely, older adults were more likely to endorse specific symptoms in Part B, with scores increasing by 1.15 points from ages 20 to 80, or about 0.23 points per decade. No safety or tolerability data were reported, as this was a psychometric analysis of a screening tool. A key limitation is that the psychometric equivalence of the ASRS remains unverified for older adult populations. The study's practice relevance is restrained but notable: standard screening practice using the ASRS may systematically underestimate ADHD symptom severity in older adults due to this measurement bias. The authors recommend using the full 18-item ASRS when screening older populations and suggest that developing age-adjusted norms would improve diagnostic accuracy.