HMN 2025: How Alzheimer’s changes appear early in patients with Down syndrome

Down syndrome is caused by an extra copy of chromosome 21. Because of genes present on this chromosome that are known to contribute to Alzheimer’s disease, patients with Down syndrome often develop the disease, sometimes at a relatively young age. However, few studies have examined Alzheimer’s-related pathological changes in the brains of people with Down syndrome, especially pediatric patients and those who are Black or Hispanic. Studies also hadn’t explored other neurodegenerative conditions in those with Down syndrome.

In a study published in the Journal of Alzheimer’s Disease, researchers led by a team at UT Southwestern examined 34 postmortem brains donated by patients with Down syndrome who underwent autopsies at UTSW between 1986 and 2023. They also incorporated findings from four previous studies, along with data from the National Alzheimer’s Coordinating Center (NACC), which collectively included an additional 126 brains from individuals with Down syndrome. The combined data encompassed a wide range of ages and races.

The findings showed that pathological changes associated with Alzheimer’s disease, such as amyloid plaques appearing as early as age 11, and tau tangles emerging by the mid-30s, were present in people with Down syndrome and increased with age, regardless of race. Other neurodegenerative conditions that frequently occur with Alzheimer’s disease were relatively rare in individuals with Down syndrome. These findings could help researchers develop unique diagnostic and therapeutic strategies for this population, the researchers concluded.

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