The Role of Genetic Alterations in the Emergence of Alzheimer's Disease in Down Syndrome: A Review.

Down syndrome (DS), the most common chromosomal disorder, is associated with an accelerated aging process, increasing the risk of early-onset Alzheimer's disease. This review examines genetic factors involved in the development of Alzheimer's disease (AD) in people with DS. A systematic search in major databases was conducted, and articles from 2020 to 2025 that met the predefined inclusion criteria were included. The results showed that the prevalence of AD was above 60% in people with DS older than 65 years, the mean age at diagnosis was 53 years, and the mortality occurred around 59 years. The main genetic factor identified was the overexpression of the APP gene, along with other genes such as DYRK1A, RCAN1, SOD1, APOEε4, and genes involved in the immune response, as well as posttranscriptional dysregulation. Diagnosis remains a challenge due to the pre-existent intellectual disability and the atypical clinical presentation of the disease; however, the development of adapted neuropsychological tests, biomarkers, and neuroimaging techniques is expected to facilitate early diagnosis. The connection between both diseases is the result of multiple genetic factors that lead to early onset and accelerated progression of AD. It is essential to achieve timely diagnosis and provide early treatment to improve quality of life of both patients and their caregivers.