Clinical study of a urinary competitve ELISA for neural thread protein in Alzheimer disease.

AD7C-NTP (neural thread protein) is a approximately 41-kD brain protein that is selectively elevated in Alzheimer disease (AD). AD7C-NTP is associated with the pathologic changes of AD, and overexpression of the AD7C-NTP gene is associated with cell death similar to that found in the AD brain. A newly developed competitive ELISA (enzyme-linked immunosorbent assay) was tested in urine samples from patients with AD, patients with non-AD dementia, and healthy normal individuals. Mean assay measurement in the AD group (30.1 +/- 10.8) was significantly higher than in the non-AD dementia control group (13.4 +/- 3.4) and in the nondementia control group (14.8 +/- 5.2) (P <.001). Mean assay measurement in early-AD cases (25.3 +/- 7.6) was significantly lower than in other AD cases (33.9 +/- 11.4). Levels of more than 18 units were found in 89% of overall AD cases and in 10% of overall controls. The results further validate urinary AD7C-NTP as a biochemical marker for AD and indicate that the competitive ELISA-format AD7C-NTP test in urine is an accurate method for determining AD7C-NTP levels in AD.