The forgotten population: Early-onset Alzheimer's in people with Down syndrome.

In recent decades, Alzheimer's disease has increasingly been discussed through narratives of prevention, resilience, and delayed onset. For individuals with Down syndrome, however, Alzheimer's disease is not a distant possibility, but an almost predictable consequence of increased longevity. The substantial rise in life expectancy in this population represents one of the greatest achievements of modern medicine. At the same time, it has exposed a profound biological vulnerability, as most individuals with Down syndrome will develop Alzheimer's disease-related neuropathology decades earlier than the general population. Although Down syndrome constitutes the most common genetic cause of Alzheimer's disease, these individuals remain largely excluded from prevention strategies, clinical trials, and global dementia agendas. This Viewpoint argues that such persistent invisibility does not reflect a lack of scientific relevance, but rather a systemic failure to align biological certainty with ethical responsibility. By highlighting the unique trajectory of Alzheimer's disease in Down syndrome, as well as the social, familial, and caregiving implications of early cognitive decline, this article calls for a necessary shift in perspective: from longevity celebrated as an endpoint to longevity recognized as an obligation to ensure inclusion, dignity, and meaningful support. If efforts to confront Alzheimer's disease are to be genuine, they must begin by including those who have lived with its burden the longest, often in silence.