Olenka Xiomara Valverde-Lopez, Brandon Lee Gutarra-García
Justification: The neurobiological basis of attention-deficit/hyperactivity disorder (ADHD) highlights the complexity of this disorder and the importance of timely diagnosis, particularly in older adults, a population in which its clinical identification remains challenging. Objective: Given the growing relevance of this condition in the fields of neuropsychology and neuroscience, this study aimed to review and synthesize the available scientific evidence on the neurobiological basis and clinical implications of undiagnosed ADHD in older adults. Methodology: A narrative review of the scientific literature was conducted. A total of 58 studies were identified, of which 19 were selected for analysis based on their relevance to the research topic. Results: The findings indicate that ADHD in older adults has a complex neurobiological basis, characterized by structural and functional alterations in frontostriatal and frontocerebellar circuits, dysfunction of the dopaminergic and noradrenergic systems, and a significant genetic contribution. Furthermore, underdiagnosis is associated with diagnostic errors, delayed treatment, and an increased risk of neuropsychiatric comorbidities. Conclusion: Undiagnosed ADHD in older adults is a complex and heterogeneous disorder. Strengthening detection and diagnostic strategies is therefore essential to promote timely clinical management and to distinguish ADHD from other neurocognitive disorders associated with aging.