Urine neural thread protein measurements in Alzheimer disease.

OBJECTIVES: Neural thread protein (NTP), a membrane-associated phosphoprotein, was selectively elevated in the urine of patients with Alzheimer disease (AD). To demonstrate the potential utility of urine NTP assays for the diagnosis of AD, we performed this study.

DESIGN: A prospective blinded multicentered study.

PARTICIPANTS: Individuals diagnosed as having probable AD (n = 49), Parkinson's disease (PD) (n = 20), and healthy controls (n = 22) were enrolled consecutively in 4 neurology centers.

MEASUREMENTS: A first morning urine sample was obtained from each subject. Urine NTP measurement using competitive ELISA was tested at the central laboratory and compared with AD and PD patients and healthy controls (HC). The testing laboratory was blinded to clinical information.

RESULTS: The mean assay value in AD (n = 49, 26.8 ± 9.4 μg/mL) was significantly higher than in HC (n = 22, 18.1 ± 6.7 μg/mL) (P ≤ .001) and than in PD (n = 20, 21.0 ± 8.5 μg/mL) (P ≤ .05). Levels of 21.6 μg/mL or higher were found in 81.6% of all AD cases, in 30.0% of PD cases, and in 13.6% of HC. Urine NTP assay measurements of AD with a Clinical Dementia Rate (CDR) of 0.5 (n = 10, 24.2 ± 5.9 μg/mL, P = .063) or of 1.0 (n = 24, 30.1 ± 10.9 μg/mL, P = .000) were significantly higher than in HC. However, the AD patients with CDR of 2.0 (n = 9, 23.1 ± 7.3 μg/mL, P = .136) were not significant.

CONCLUSION: Urine NTP could be used as a safe and promising biochemical marker of early AD.