Complement activation mainly mediates the association of heart rate variability and cognitive impairment in adults with obstructive sleep apnea without dementia.

STUDY OBJECTIVES: The relationship between autonomic nervous system dysfunction measured by heart rate variability (HRV) and cognitive impairment in obstructive sleep apnea (OSA) patients is complex and still not well understood. We aimed to analyze the role of complement activation, Alzheimer's disease (AD) biomarkers, and white matter hyperintensity (WMH) in modulating the association of HRV with cognitive performance. METHODS: There were 199 subjects without dementia, including 42 healthy controls, 80 OSA patients with mild cognitive impairment (MCI), and 77 OSA patients without cognitive impairment. All participants who completed polysomnography, cognition, WMH volume, and 5-min HRV analysis were recorded during wakefulness and sleep periods. Neuron-derived exosome and astrocyte-derived exosome proteins were measured by ELISA kits. RESULTS: The OSA with MCI group were associated with a lower mean of standard deviations of R-R intervals for 5-min intervals (SDANN index) during wakefulness, standard deviation of the R-R interval (SDNN) during sleep stage and percentage of adjacent R-R intervals differing by more than 50 ms (PNN50) in each stage compared with OSA without MCI. The influence of HRV on cognition was partially mediated by complement activation (C5b-9 mediated a maximum of 51.21%), AD biomarkers, and WMH. CONCLUSIONS: Lower SDANN index and PNN50 during wakefulness and SDNN and PNN50 during sleep periods were found in OSA patients with MCI, suggesting potential vulnerability to autonomic and parasympathetic dysfunction. Complement activation, AD biomarkers, and WMH might partially mediate and interact with the influence of HRV on cognitive impairment in OSA patients. CLINICAL TRIAL REGISTRATION: ChiCTR1900021544.

Plasma Phospholipids are Associated with Mild Cognitive Impairment in Type 2 Diabetic Patients.

BACKGROUND: Phospholipids and their metabolisms are closely allied to nosogenesis and aggravation of Type 2 diabetes mellitus and cognitive impairment. The aim of this study is to characterize the plasma levels of phospholipids in type 2 diabetes patients and type 2 diabetes patients with mild cognitive impairment (MCI), and to identify potential biomarkers of type 2 diabetes patients with MCI. METHODS: In this cross-sectional study, a total of 374 type 2 diabetes patients were prospectively enrolled. There were 103 patients with MCI and 271 patients without MCI. Plasma levels of lysophosphatidic acid (LPA) and phospholipids with solubility similar to that of LPA (PSS-LPA) were assayed. RESULTS: Plasma LPA and PSS-LPA levels were significantly higher in patients with MCI than those without MCI (P = 0.007, P ＜ 0.001). A logistic regression analysis indicates that elevated plasma PSSLPA was associated with increased risk of MCI in type 2 diabetic patients, with an OR of 1.87 (1.04- 3.47) after additional adjustment for hyperlipidemia, hypertension, High-sensitivity C-reactive protein, hemoglobin A1c, Intima-media thickness, ankle brachial index, and brachial-ankle pulse wave velocity. In type 2 diabetic patients with MCI, there were negative correlations between plasma LPA, PSS-LPA and the MoCA scores (r =﹣0.322, P < 0.01; r =﹣0.349, P < 0.001). Furthermore, plasma PSS-LPA exhibited a fair diagnostic value for MCI, with an area under the curve of 0.86. CONCLUSION: The level of plasma PSS-LPA may be an important biomarker for diagnosis of MCI.

Biomarkers of Renal Function in Type 2 Diabetic Patients with Cognitive Impairment.

Kidney disease is associated with cognitive impairment in studies of nondiabetic adults. We examined the cross-sectional relation between three measures of renal function and cognitive impairment (CI) in type 2 diabetic patients. A total of 357 patients with type 2 diabetes were prospectively enrolled. There were 108 patients with CI and 249 patients without CI (control). We calculated the urinary albumin/creatinine ratio (UACR) from morning spot urine and the estimated glomerular filtration rate (eGFR) in serum samples. Serum Cystatin C (Cys C) was measured with an automated particle-enhanced turbidimetric immunoassay. UACR and Cystatin C levels were significantly higher in patients with CI than those without CI (P<0.001), and the eGFR was lower in patients with CI than those without (P=0.003). A logistic regression analysis indicates that kidney impairment biomarkers levels were significantly associated with an increased risk of CI after adjustment for age and gender. The OR of each kidney biomarker (eGFR, UACR, Cystatin C) for CI status was 1.78 (0.89-3.27), 2.36 (1.29-4.42), and 2.77 (1.36-5.97), respectively. Among three kidney biomarkers (eGFR, UACR, Cystatin C), only elevated serum Cystatin C was associated with increased risk of CI in type 2 diabetic patients, with an OR of 1.42 (1.25-4.24) after additional adjustment for duration of diabetes, hypertension, hyperlipidemia, hemoglobin A1c (HbA1c), high-sensitivity C-reactive protein (Hs-CRP), intima-media thickness (IMT), ankle brachial index (ABI), and brachial-ankle pulse wave velocity (ba-PWV). Furthermore, combination of conventional risk factors and Cystatin C levels exhibited a fair diagnostic value for CI, with an area under the curve (AUC) of 0.91. Among three kidney impairment biomarkers (eGFR, UACR, Cystatin C), only elevated serum Cystatin C was associated with increased risk of CI in type 2 diabetic patients, independent of conventional risk factors. Furthermore, Cystatin C may be a better marker for CI than eGFR and UACR, and exhibited diagnostic value.

Associations between biomarkers of renal function with cerebral microbleeds in hypertensive patients.

BACKGROUND: Cerebral microbleeds (CMBs) have been observed in the elderly and have been regarded as a manifestation of small vessel disease (SVD). Cerebral and glomerular SVD may have a common source of pathogenesis because these organs are closely connected through anatomic and hemodynamic similarities. The purpose of this study was to clarify the associations between kidney biomarker levels and CMBs in hypertensive patients. METHODS: The presence and number of CMBs were assessed on susceptibility-weighted imaging. We calculated the urinary albumin/creatinine ratio (UACR) from morning spot urine and the estimated glomerular filtration rate (eGFR) in serum samples. Serum cystatin C (CysC) was measured with an automated particle-enhanced turbidimetric immunoassay. RESULTS: UACR and CysC levels were higher in the patients with CMBs than those without, and the eGFR was lower in the patients with CMBs than those without. A logistic regression analysis indicates that eGFR and UACR were independently associated with the prevalence of deep or infratentorial CMBs. The odds ratio (OR) (95% confidence interval (CI)) of eGFR and UACR was 1.95 (1.37-3.27) and 2.25 (1.66-4.46), respectively. CysC was independently associated with CMBs in both deep or infratentorial and lobar locations. The ORs (95% CI) were 2.59 (1.57-6.22) and 1.57 (1.15-4.85), respectively. Furthermore, CysC exhibited fair diagnostic value for CMBs, with an area under the curve of 0.80. CONCLUSIONS: Kidney biomarker levels are associated with the presence of CMB in hypertensive patients without a history of transient ischemic attack (TIA) or stroke, independent of conventional risk factors, and CysC was a better marker for CMBs than eGFR and UACR.

Serum cystatin C and cerebral microbleeds in patients with acute cerebral stroke.

Recent studies have shown that kidney dysfunction is associated with cerebral microbleeds (CMB). Cystatin C is a more useful measurement than creatinine-based estimating equations for evaluating kidney function. The purpose of this study was to clarify the relationship between cystatin C levels and CMB in patients with acute cerebral stroke. This cross-sectional study included a total of 485 patients with acute ischemic stroke and 129 patients with cerebral hemorrhage. The serum levels of cystatin C were significantly higher in acute cerebral stroke patients with CMB than in those without (p<0.001). Multivariate logistic regression analyses showed that for each single standard deviation increase of cystatin C levels, there was a significant increase in the presence of CMB after adjusting for age and sex, and after additional adjustment for cardiovascular risk factors, silent lacunar infarction, and white matter hyperintensity in patients with acute stroke. The odds ratio (95% confidence interval) in patients with acute cerebral infarction and cerebral hemorrhage were 2.92 (1.81-6.93) and 2.98 (1.76-6.97), respectively. The present study suggests that elevated levels of cystatin C are associated with the presence of CMB in acute stroke patients, independent of conventional risk factors.