Plasma Tau Levels in Cognitively Normal Middle-Aged and Older Adults.
Using an ultra-sensitive technique, an immunomagnetic reduction assay, the plasma tau level can be measured to a limit of quantification of pg/ml. In total 126 cognitively normal middle-aged and older adults (45-95 years old) were recruited. The plasma tau levels were significantly higher in the older group (aged 65-95 years) 18.14 ± 7.33 pg/ml than those in the middle-aged group (aged 45-64 years) 14.35 ± 6.49 pg/ml when controlled gender andApoEε4 carrier status (F= 3.102,P= 0.029). TheApoEε4 carriers had higher plasma tau levels than the non-carriers when controlled age and gender (F= 6.149,P= 0.001). Men had higher plasma tau levels than their women counterparts when controlledApoEε4 carrier status and gender (F= 6.149,P= 0.001). The plasma tau levels were found to be positively associated with their ages (r= 0.359,P< 0.001). Regression analysis showed that age explained approximately 13% of the variance in the plasma tau levels, and explained more than 10% of the variance in the volumes of the hippocampus and white matter hypodensity (R2change 0.123~0.167, allP< 0.001), and explained less than 10% of the variance in the volume of the amygdala, and central part of the corpus callosum (R2change 0.085~0.097, allP= 0.001). However, the plasma tau levels do not further explain any residual variance in the volume of brain structures. In conclusion, the effect of age on the plasma tau levels should always be considered in clinical applications of this surrogate biomarker to middle-aged and elderly subjects.
Department of Neurology, National Taiwan University Hospital, College of Medicine, National Taiwan UniversityTaipei, Taiwan; Graduate Institute of Brain and Mind Sciences, College of Medicine, National Taiwan UniversityTaipei, Taiwan; Department of Psychology, National Taiwan UniversityTaipei, Taiwan; Graduate Institute of Biomedical Engineering and Bioinformatics, National Taiwan UniversityTaipei, Taiwan.
Ming-Jang
MJ
Chiu
Graduate Institute of Brain and Mind Sciences, College of Medicine, National Taiwan UniversityTaipei, Taiwan; Section of Neurology, Department of Psychosomatic Medicine, Taipei City HospitalTaipei, Taiwan.
Ling-Yun
LY
Fan
Department of Neurology, National Taiwan University Hospital, College of Medicine, National Taiwan University Taipei, Taiwan.
Ta-Fu
TF
Chen
Department of Medical Imaging, National Taiwan University Hospital, College of Medicine, National Taiwan University Taipei, Taiwan.
Ya-Fang
YF
Chen
Institute of Electro-Optical Science and Technology, National Taiwan Normal University Taipei, Taiwan.
Jen-Jei
JJ
Chieh
Institute of Electro-Optical Science and Technology, National Taiwan Normal University Taipei, Taiwan.
Herng-Er
HE
Horng
age; biomarker; immunomagentic reduction assay; normal cognition; plasma tau