<b>Clinical Characteristics Associated with ASRS-Based Probable Adult ADHD Among Adults Receiving Treatment for Substance Use Disorders in Kenya</b>

Adult Attention-Deficit/Hyperactivity Disorder (ADHD) commonly co-occurs with Substance Use Disorders (SUDs), yet evidence on associated clinical characteristics among treatment-seeking adults in Kenya remains limited. This cross-sectional analytical study examined clinical characteristics associated with ASRS-based probable adult ADHD among 322 adults recruited through total enumeration of eligible patients in six purposively selected rehabilitation centres in Nairobi, Kenya. Data were collected using a socio-demographic questionnaire, the Adult ADHD Self-Report Scale Version 1.1 (ASRS v1.1), Alcohol Use Disorders Identification Test (AUDIT), and Drug Abuse Screening Test (DAST-10). Bivariate analyses and multivariable binary logistic regression were used to examine associations with ADHD screening classification. Overall, 28.0% of participants met criteria for ASRS-based probable ADHD. Probable ADHD was associated with greater alcohol use severity (r_pb = .301, p < .001), greater drug use severity (r_pb = .329, p < .001), earlier age at first substance use (r_pb = −.316, p  < .001), and polysubstance use (χ² = 22.11, p < .001). In the adjusted model, each additional year in age at first substance use was associated with 13% lower odds of probable ADHD (aOR = 0.87, 95% CI [0.81, 0.93]), while polysubstance use was associated with approximately fivefold higher odds (aOR = 5.10, 95% CI [2.05, 12.72]); both p < .001. Earlier substance- use initiation and polysubstance use were independently associated with probable ADHD. These findings support consideration of ADHD screening followed by comprehensive clinical assessment within SUD treatment settings.