Cerebrospinal beta-amyloid (1–42) in early Alzheimer's disease: association with apolipoprotein E genotype and cognitive decline

The concentration of beta-Amyloid (1–42) protein (Aβ42) in cerebrospinal fluid (CSF) was determined in 75 Alzheimer's disease (AD) patients, 35 patients with other causes of dementia and 30 cognitively healthy age-matched controls. A significant decrease of Aβ42 concentration was found in AD patients, even in 25 subjects with very mild dementia as compared to patients with other causes of dementia and controls. Within AD patients we observed a significant decline of Aβ42 from very mild to mild and moderate dementia. In addition, Aβ42 levels were negatively correlated with the severity of cognitive impairment and with the number of ε4 alleles inherited. We conclude that measurement of Aβ42 in CSF might be helpful for identifying AD at an early stage and also for tracking the clinical course.