Investigations of Memory Monitoring in Individuals With Subjective Cognitive Decline and Amnestic Mild Cognitive Impairment.

BACKGROUND: Subjective cognitive decline (SCD) has been called the prodromal stage of amnestic mild cognitive impairment (aMCI); however, further investigation is needed to confirm this observation. OBJECTIVE: To define the relationship between SCD and aMCI. METHOD: In this case-control study, we used the feeling-of-knowing in episodic memory (FOK-EM) test to measure the memory-monitoring function of 40 adults with aMCI, 60 with SCD, and 55 healthy controls. RESULTS: The recognition rates of FOK-EM (53.53% ± 7.82%; 55.12% ± 6.08%) and judgment accuracy of the aMCI and SCD groups (γ values 0.21 ± 0.11; 0.30 ± 0.16) were significantly lower than those of the control group (72.32% ± 5.14%; 0.57 ± 0.16) (F = 116.24, P < 0.01; F = 128.57, P < 0.01; F = 73.33, P < 0.01). The scores for correct decision/correct recognition (RR; 27.2 ± 6.43; 29.36 ± 5.16) and correct decision/false recognition (RF; 30.41 ± 5.06; 27.26 ± 4.37) of the aMCI and SCD groups were also significantly lower than those of the control group (49.35 ± 7.13; 11.16 ± 4.35) (FRR = 132.67, P < 0.01; FRF = 131.8, P < 0.01). CONCLUSION: Mild clinical impairments in memory-monitoring function may precede clinically confirmed objective memory impairment in individuals with SCD.

CHOP/ORP150 ratio in endoplasmic reticulum stress: a new mechanism for diabetic peripheral neuropathy.

BACKGROUND/AIMS: Peripheral neuropathy is a frequent and severe diabetic complication characterized by progressive loss of peripheral nerve axons and manifested by pain and eventually complete loss of sensation. Effective therapy for diabetic peripheral neuropathy (DPN) is still lacking due to our limited understanding of the mechanisms for nerve injury. METHODS: Here we tested the roles of endoplasmic reticulum (ER) stress and the ER stress-activated pro-apoptotic protein CHOP and anti-apoptotic protein ORP150 in DPN in a rat model of high-fat/streptozotocin diabetes and in cultured Schwann cells (SCs). RESULTS: No significant DPN was seen in the early stage of diabetes (4 weeks following verification of diabetes). However, after prolonged diabetes (16 weeks following verification of diabetes), DPN was severely developed as reflected by slowed motor and sensory nerve conduction velocity, blunted thermal nociception, and decreased intraepidermal nerve fiber profiles in the hindpaw. Meanwhile, while it was not noticed in sciatic nerves of early diabetes, ER stress in prolonged diabetic rats was indicated by robust increases in H2O2 production and expression of the ER chaperon glucose-regulated protein 78 (GRP78). ORP150 expression was substantially upregulated, accompanied by mild increase in CHOP expression, resulting in a low CHOP/ORP150 ratio, in early diabetes. In contrast, with prolonged diabetes, CHOP expression exceeded ORP150 expression, resulting in an increased CHOP/ORP150 ratio. In vivo knockdown of ORP150 induced DPN in early diabetes and exacerbated the DPN after prolonged diabetes, whereas knockdown of CHOP ameliorated DPN in rats with prolonged diabetic. On the other hand, in vitro knockdown of ORP150 promoted high glucose-induced SC apoptosis, whereas knockdown of CHOP protected SCs from apoptosis. CONCLUSION: Taken together, we have provided evidence for the critical role of ER stress in the development of DN and also uncovered CHOP/ORP150 ratio as an important mechanism for determining neuronal apoptosis during ER stress. In the early stage of diabetes, CHOP/ORP150 ratio was relatively low favoring neuronal cell survival, whereas after prolonged diabetes, CHOP/ORP150 ratio increased resulting in apoptotic cell death leading to accelerated DPN.

Features of Cerebral Small Vessel Disease Contributes to the Differential Diagnosis of Alzheimer's Disease.

BACKGROUND: Cerebral small vessel disease (CSVD), which comprises the typical features of white matter hyperintensity (WMH) and Vichor-Robin spaces (VRSs) in the brain, is one of the leading causes of aging-related cognitive decline and, ultimately, contributes to the occurrence of dementia, including Alzheimer's disease (AD). OBJECTIVE: To investigate whether CSVD imaging markers modify the pathological processes of AD and whether these markers improve AD diagnosis. METHODS: 208 participants were enrolled in the China Aging and Neurodegenerative Initiative (CANDI). Fluid AD biomarkers were detected using a single-molecule array, and cerebral small vessel dysfunction was determined using magnetic resonance imaging. RESULTS: WMH contributed to AD pathology only within the NC and MCI groups (CDR ≤0.5), whereas VRSs had no effect on AD pathology. The associations between AD biomarkers and cognitive mental status were consistent with the presence of CSVD pathology. That is, within individuals without CSVD pathology, the MMSE scores were correlated with AD fluid biomarkers, except for plasma Aß42 and Aß40. Increased plasma p-Tau levels were associated with worse cognitive performance in individuals with WMH (ß= -0.465, p = 0.0016) or VRSs (ß= -0.352, p = 0.0257) pathology. Plasma AD biomarkers combined with CSVD markers showed high accuracy in diagnosing dementia. CONCLUSION: Findings from this cross-sectional cohort study support the notion that CSVD is a risk factor for dementia and highlights that vascular pathology can promote AD biomarker levels, especially in the early course of the disease. Moreover, our results suggest that adding a vascular category to the ATN framework improves the diagnostic accuracy of AD.

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.