Abstract
Dementia in Alzheimer's disease (AD) is ultimately due to cell loss mediated by several mechanisms including, apoptosis, impaired mitochondrial function, and possibly necrosis. A second major neuroanatomic correlate of dementia is aberrant cortical neuritic sprouting with abundant proliferation of dystrophic neurites. Early in vivo detection of AD will require non-invasive assays of highly sensitive and relatively specific biomarkers that reflect these fundamental abnormalities in cellular function. The AD-associated neuronal thread protein (AD7c-NTP) gene encodes a ~ kD membrane-spanning phosphoprotein that causes apoptosis and neuritic sprouting in transfected neuronal cells. The AD7c-NTP gene is over-expressed in AD beginning early in the course of disease. In the brain, increased AD7c-NTP immunoreactivity is associated with phospho-tau-immunoreactive cytoskeletal lesions, but not with amyloid-β accumulations. The levels of AD7c-NTP in postmortem brain tissue correlate with the levels measured in paired ventricular fluid samples, suggesting that the protein is secreted or released by dying cells into cerebrospinal fluid (CSF). In this regard, elevated levels of AD7c-NTP can be detected in both CSF and urine of patients with early or moderately severe AD, and the CSF and urinary levels of AD7c-NTP correlate with the severity of dementia. The newest configuration of the AD7c-NTP assay, termed ``7c Gold'', has greater than 90% aggregate results from a number of studies suggest that AD7c-NTP is an excellent biomarker that could be helpful in the routine clinical evaluation of elderly patients at risk for AD.