Clinical Study Alzheimer-associated urine neuronal thread protein level increases with age in a healthy Chinese population Lina Ma a,b , Juan Chen a , Rong Wang a,⇑ , Ying Han c , Jingshuang Zhang a , Wen Dong a , Zhiwei Zhao a , Youqin Liu d , Xi Chu d a Central Laboratory, Xuanwu Hospital of Capital Medical University, Key Laboratory for Neurodegenerative Disease of Ministry of Education, Center of Alzheimer’s Disease, Beijing Institute for Brain Disorders, #45 Changchun Street, Xicheng District, Beijing 100053, China b Department of Geriatrics, Xuanwu Hospital of Capital Medical University, Beijing, China c Department of Neurology, Xuanwu Hospital of Capital Medical University, Beijing, China d Department of Medical Center, Xuanwu Hospital of Capital Medical University, Beijing, China article info Article history: Received 28 January 2014 Accepted 23 April 2014 Keywords: Age Alzheimer-associated neuronal thread protein ELISA Urine abstract Alzheimer-associated neuronal thread protein (AD7c-NTP) has been found to be a biomarker for Alzhei- mer’s disease (AD) with elevated levels in the cerebrospinal fluid and urine from AD patients in the early stage of the disease. Whether the urine level of AD7c-NTP in healthy people is age-related is still unclear. We aimed to measure the level of urine AD7c-NTP in a healthy Chinese population of different ages. Urine samples of 294 subjects were collected from the Department of Health Examination Center at Xuanwu Hospital of Capital Medical University, China. The samples were divided into five groups by age: Group 1 (20–29 years), Group 2 (30–39 years), Group 3 (40–49 years), Group 4 (50–59 years) and Group 5 (P60 years). The Mini Mental State Examination and Montreal Cognitive Assessment were carried out. The level of AD7c-NTP in the urine specimen was detected by enzyme-linked immunosorbent assay. The urine AD7c-NTP levels in Group 1, 2, 3, 4 and 5 were 0.3012 ± 0.2373, 0.3702 ± 0.2422, 0.3914 ± 0.2442, 0.4844 ± 0.2908 and 0.5880 ± 0.2638 ng/ml (mean ± standard error of the mean), respec- tively. The urine AD7c-NTP levels among the five groups differed significantly (F = 6.181, p = 0.00). Females had a higher urine AD7c-NTP content than males, and the urine AD7c-NTP level increased with age (r = 0.28, p = 0.00). To our knowledge this study is the first to show that urine AD7c-NTP level increases with age in a healthy Chinese population without cognitive dysfunction. This study suggests that different cut-off values aimed at different age groups should be established for diagnosing cognitive impairments in clinical practice. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction Alzheimer’s disease (AD) is an age-related chronic degenerative disease that damages the nervous system, but its etiology is still unknown [1,2]. Currently available AD therapies can only alleviate or delay clinical symptoms [3]. The diagnosis of AD is mainly based on medical history, clinical symptoms, psychological tests, and the exclusion of other types of dementia. A definitive diagnosis of AD can only be achieved after autopsy [4]. Thus, simple and non-inva- sive biomarker tests for early detection of AD are urgently required. To our knowledge no extracerebral diagnostic biomarkers in the urine, serum or connective tissue have been validated for the diagnosis of AD [5]. Alzheimer-associated neuronal thread protein (AD7c-NTP) is a biomarker for AD that has been found at elevated levels in the cerebrospinal fluid (CSF) and urine from AD patients in the early stage of the disease [6]. Studies have found that the level of AD7c-NTP in CSF and urine is related to the severity of dementia [7,8]. Further studies have shown that in patients with AD, exam- ination of AD7c-NTP in urine can give similar results to that in CSF [9,10]. Examination is more easily performed in urine than CSF. The urine AD7c-NTP test is non-invasive, and the development of urine AD7c-NTP diagnostic kits would make screening and early diagno- sis of AD more convenient. Two issues, however, remain unclear. First, it is unknown whether the level of urine AD7C-NTP increases with age in healthy people. Second, it is unknown whether there are different cut-off values of urine AD7C-NTP level for different age groups. Thus, we aimed to investigate the level of urine AD7c-NTP in different age groups of healthy Chinese people. http://dx.doi.org/10.1016/j.jocn.2014.04.028 0967-5868/Ó 2014 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. Tel./fax: +86 10 6315 9572. E-mail address: rong_wang72@aliyun.com (R. Wang). Journal of Clinical Neuroscience 21 (2014) 2118–2121 Contents lists available at ScienceDirect Journal of Clinical Neuroscience journal homepage: www.elsevier.com/locate/jocn