Adult ADHD Self-Report Scale (ASRS-18): Validity evidence, a proposed factor structure, measurement invariance, and screening utility in Brazilian adults

= .50). Receiver operating characteristic (ROC) analyses indicated discrimination of reported ADHD diagnosis status by total score (AUC = .83), Inattention factor (AUC = .83), and six-item Part A screener (AUC = .82). Positive predictive values fell under realistic base rates, so a positive result indicates further assessment; cutoffs were stable but remain preliminary and sample-specific. Significant correlations between ASRS-18 domains and measures of anxiety, depression, perceived stress, and impulsive buying supported validity based on relations with external variables. Findings provide evidence for validity and score reliability of the ASRS-18 in Brazilian adults.