Amyloid β concentrations in older people with Down syndrome and dementia

People with Down syndrome develop Alzheimer's disease with an early age of onset. Plasma amyloid beta (A beta) levels were measured in individuals with Down syndrome who were over the age of 40. No associations between age and A beta 1-40 and A beta 1-42 concentrations were found and nor were A beta 1-40 and A beta 1-42 levels found to vary between those with Alzheimer's-type dementia and those without dementia. The APOE genotype was not found to have an impact upon A beta 1-40 or A beta 1-42 concentrations. These data suggest that other factors play important roles in determining the onset and progression of dementia in the Down syndrome population. (C) 2008 Elsevier Ireland Ltd. All rights reserved.