Mixed Neuropathologies in Adults with Down Syndrome: Frequency of Alzheimer's Disease and Co-pathologies

This neuropathological study of 63 adults with Down syndrome (age >40 years) examined the prevalence of Alzheimer's disease neuropathological change and co-existing pathologies including cerebral amyloid angiopathy, Lewy pathology, and TDP-43 encephalopathy. Pure Alzheimer's pathology was found in only 29% of cases, while cerebral amyloid angiopathy was present in 84%, and individuals with dementia showed significantly lower brain weight and more severe hippocampal atrophy than those without dementia.