Adults with Down syndrome develop the neuropathological hallmarks of Alzheimer's disease and are at very high risk of developing early-onset dementia, which is now the leading cause of death in this population. Diagnosis of dementia remains a clinical challenge because of the lack of validated diagnostic criteria in this population, and because symptoms are overshadowed by the intellectual disability associated with Down syndrome. In people with Down syndrome, fluid and imaging biomarkers have shown good diagnostic performances and a strikingly similar temporality of changes with respect to sporadic and autosomal dominant Alzheimer's disease. Most importantly, there are no treatments to prevent Alzheimer's disease, even though adults with Down syndrome could be an optimal population in whom to conduct Alzheimer's disease prevention trials. Unprecedented research activity in Down syndrome is rapidly changing this bleak scenario that will translate into disease-modifying therapies that could benefit other populations.

患有唐氏综合症的成年人会出现阿尔茨海默氏病的神经病理学特征，并且患早发性痴呆的风险非常高，而早发性痴呆现在是该人群的主要原因。痴呆症的诊断仍然是一个临床挑战，因为该人群缺乏经过验证的诊断标准，而且唐氏综合症相关的智力障碍掩盖了症状。在唐氏综合症患者中，液体和成像生物标志物显示出良好的诊断性能，并且与散发性和常染色体显性阿尔茨海默氏病的变化时间惊人相似。最重要的是，尽管患有唐氏综合症的成年人可能是进行阿尔茨海默病预防试验的最佳人群，但目前还没有预防阿尔茨海默病的治疗方法。唐氏综合症前所未有的研究活动正在迅速改变这种黯淡的情况，这将转化为可以造福其他人群的疾病缓解疗法。