Study Design: Retrospective case series. Objectives: The objective of this study was to provide naturalistic data on the use of guanfacine for the treatment of attention-deficit/hyperactivity disorder (ADHD) in a clinically referred sample of youth with Down syndrome (DS). Methods: The medical records of children and adolescents with DS who received guanfacine for the treatment of ADHD from a multidisciplinary neurodevelopmental disorder clinic between September 1, 2011, and September 10, 2021, were reviewed. Demographic and clinical characteristics, guanfacine dose and treatment duration, and adverse effects were recorded. Clinical Global Impression Scale (CGI) scores for ADHD symptom severity (S) and improvement (I) were retrospectively assigned by a child and adolescent psychiatrist based on review of the clinic notes. Response to guanfacine was defined as completion of at least 12 weeks of treatment and a Clinical Global Impression Improvement subscale rating ≤2 (1 = "very much improved" or 2 = "much improved"). Results: Twenty-one patients were eligible for inclusion, of whom 17 (81%) completed at least 12 weeks of guanfacine. Ten of the 21 patients (48%; 95% confidence interval [CI]: 28%-68%) responded to treatment. The median time on guanfacine treatment covered by the clinic notes was 50.4 weeks, with a range of 0.3 weeks to 7.5 years. Thirteen patients (62%) remained on guanfacine at the time of their most recent clinic note. Nine patients had adverse events documented in their clinic notes (43%; 95% CI: 24%-63%), most commonly sleepiness (n = 7) and constipation (n = 2). Conclusion: About half of patients with DS responded to guanfacine for the treatment of ADHD and many tolerated long-term use. Study limitations primarily relate to the retrospective nature of the study and small sample size.
Keywords: Down syndrome; attention-deficit/hyperactivity disorder; guanfacine.