• Alzheimer's disease;
  • amyloid precursor protein;
  • neuropsychological correlates

The comprehensive cognitive screens for dementia, the Cambridge Cognitive screen (CAMCOG) and the Informant Questionnaire for Cognitive Decline in the Elderly (IQCODE) were used for assessing use of the putative Alzheimer's disease biological marker, plasma amyloid precursor protein (APP), in Alzheimer's disease and Down syndrome. The analysis suggested that there were significant correlations between amyloid precursor protein and cognitive decline as assessed by the IQCODE. Preliminary investigations of Down syndrome suggest amyloid precursor protein levels are associated with duration of dementia in the group. The findings imply circulating amyloid precursor protein has a more central role in the pathogenesis of Alzheimer's disease.