Plasma Core Alzheimer's Disease Biomarkers Predict Amyloid Deposition Burden by Positron Emission Tomography in Chinese Individuals with Cognitive Decline.

Blood-based biomarkers have been considered as a promising method for the diagnosis of Alzheimer's disease (AD). The reliability and accuracy of plasma core AD biomarkers, including phosphorylated tau (P-tau181), total tau (T-tau), Aß42, and Aß40, have also been confirmed in diagnosing AD and predicting cerebral ß-amyloid (Aß) deposition in Western populations, while fewer research studies have ever been conducted in China's Han population. In this study, we investigated the capability of plasma core AD biomarkers in predicting cerebral Aß deposition burden among the China Aging and Neurodegenerative Disorder Initiative (CANDI) cohort consisting of cognitively normal (CN), mild cognitive impairment (MCI), AD dementia, and non-Alzheimer's dementia disease (Non-ADD). Body fluid (plasma and CSF) AD core biomarkers were measured via single-molecule array (Simoa) immunoassay. The global standard uptake value ratio (SUVR) was then calculated by 18F-florbetapir PET, which was divided into positive (+) and negative (-). The most significant correlation between plasma and CSF was plasma P-tau181 (r = 0.526, P < 0.0001). Plasma P-tau181 and P-tau181/T-tau ratio were positively correlated with global SUVR (r = 0.257, P < 0.0001; r = 0.263, P < 0.0001, respectively), while Aß42 and Aß42/Aß40 ratio were negatively correlated with global SUVR (r = -0.346, P < 0.0001; r = -0.407, P < 0.0001, respectively). Interestingly, voxel-wise analysis showed that plasma P-tau181 and P-tau181/T-tau ratio were negatively related to 18F-florbetapir PET in the hippocampus and parahippocampal cortex. The optimal predictive capability in distinguishing all Aß+ participants from Aß- participants and MCI+ from MCI- subgroups was the plasma P-tau181/T-tau ratio (AUC = 0.825 and 0.834, respectively). Our study suggested that plasma P-tau181 and P-tau181/T-tau ratio possessed better diagnostic and predictive values than plasma Aß42 and Aß42/Aß40 in this cohort, a finding that may be useful in clinical practices and trials in China.

Correlation between Cerebrospinal Fluid Core Alzheimer's Disease Biomarkers and ß-Amyloid PET in Chinese Dementia Population.

The current diagnoses of Alzheimer's disease (AD) mainly rely on such measures as amyloid-ß (Aß) and tau neuropathology biomarkers in vivo via cerebrospinal fluid (CSF) and positron emission tomography (PET) imaging, which had been systematically studied in Caucasian individuals, whereas diagnostic performances of these approaches in Chinese dementia population still remain unclear. This study investigated the associations between the levels of CSF core AD biomarkers, including phosphorylated tau (p-Tau181), total tau (t-Tau), Aß42, and Aß40 measured by the single-molecule array (Simoa) and cerebral Aß deposition status assessed by 18F-Florbetapir PET (Aß PET), and evaluated the predictive values of CSF core AD biomarkers in discriminating Aß PET status in a clinical dementia cohort of the Chinese population, which consisted of patients with mild cognitive impairment (MCI), AD dementia, and non-Alzheimer's dementia disease (Non-ADD). Global standard uptake value ratios (SUVRs) were calculated by Aß PET, which was divided into positive (Aß+) and negative (Aß-) through visual analysis. CSF p-Tau181 and p-Tau181/t-Tau ratio were positively correlated with the global SUVR, while CSF Aß42 and Aß42/Aß40 ratio were negatively correlated with the global SUVR. CSF Aß40 has the highest predictive value in discriminating the MCI group from the AD group, while CSF p-Tau181 was applied to discriminate the AD group from the non-ADD group. CSF Aß42/Aß40 ratio, as the optimal predictive factor, was combined with APOE ε4 status rather than age and education, which could improve the predictive ability in differentiating the Aß+ group from the Aß- group. The results reveal the universal applicability of CSF core AD biomarkers and Aß PET imaging in Chinese dementia population, which is helpful in clinical practice and drug trials in China.