RESUMEN
Introduction: Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental condition with severe and life-long consequences. Adolescents and young adults represent a particularly vulnerable subgroup because of the unique demands of their developmental stage. Despite the well-known efficacy of medication treatment for ADHD, there remains a notable concern regarding poor medication adherence in this population. Objectives: This systematic literature review aimed to synthesize the existing empirical evidence on the outcomes and consequences of medication nonadherence among adolescents and young adults with ADHD. Methods: An extensive database search was conducted on September 26, 2022, with no time limits applied. The databases included Scopus, PubMed, CINAHL, Cochrane, and PsycINFO. Results: Six studies met the inclusion criteria. Each study revealed that medication nonadherence was associated with a range of adverse outcomes, including decreased academic performance, heightened familial, and psychological stress, and an increased likelihood of substance use, pregnancy, obesity, and injury. Conversely, adherence led to improvements in at least one ADHD-related outcome. Conclusions: Research exploring the consequences of suboptimal medication adherence in adolescents and young adults with ADHD is currently limited, and effective strategies to address this issue remain scarce. A thorough understanding of such consequences is critical for developing interventions aimed at improving medication adherence and mitigating the risk of adverse outcomes, especially considering the susceptibility of this population.