Biochemical assay for amyloid β deposits to distinguish Alzheimer's disease from other dementias

Biochemical markers for Alzheimer's disease (AD) are of great value for precise diagnosis and in studies of the pathogenetic processes of this disease. A new biochemical assay allowing to differentiate AD from other forms of dementia is described. The assay is based on the extraction of amyloid β (Aβ) from milligram amounts of brain tissue by using 20% acetonitrile in 0.1% trifluoroacetic acid and its detection by Western blotting. The presence of the 4 kDa Aβ was demonstrated in all cases of AD (n=8) that were diagnosed by the independent histopathological examination of the postmortem tissues. No Aβ was found in tissue extracts from seven out of eight cases of other forms of dementia. In contrast to other biochemical techniques of Aβ detection in brain, the developed assay is simple; it does not require any special equipment and allows detection of Aβ using milligram amounts of brain tissue.