| Background:The oldest old refers to people older than 80 years. With the rapid development of economy, there was a great improvement in the people's living standards, the medical security system and the scientific and technological progress. The life expectancy of the population gradually increased accompany with a lot of question such as the aging population what will become a problem to solve urgently in China. The newest epidemiological investigation show that some diseases that are closely related to age had a increasing prevalence rate in the elderly,such as arteriosclerosis, high blood pressure, dementia and so on. Wall shear stress(WSS) represents the frictional force per unit area exerted by circulating blood on the endothelial surface of the arterial wall in the direction of flow.Low carotid WSS is closely associated with a wide variety of systemic vascular risk factors such as age, hypertension, insulin resistance, and low physical exercise.It is well established that carotid artery is an “observation window” for systemic structure and function of arteries in humans,for the intima media thickness can reflect the degree of atherosclerosis in coronary artery, cerebral artery, peripheral artery.Evidences have shown that mean WSS and peak WSS significantly decreased with increasing age,however,the incidence of cerebral white matter in the elderly is higher than the other age groups.So we speculate that the low WSS in carotid artery has certain relation with brain white matter lesions in the elderly.From these standpoints,we believe that it is important to do some research on this phenomenon, and to explore the law of development, for the prevention and treatment of elderly patients with cognitive disorders and related diseases, to cope with the coming of aging population.Objective:To investigate the associations between carotid wall shear stress(WSS) and white matter lesions or cognitive impairment in oldest old.Methods:A total of 362 oldest old subjects aged 80 years or over were categorized into three groups by the tertile of either mean WSS or peak WSS, namely, low mean WSS tertile group, middle mean WSS tertile group and high mean WSS tertile group and low peak WSS tertile group, middle peak WSS tertile group and high peak WSS tertile group.A questionnaire survey was used to investigate the gender, age, smoking history, drinking history, education, history of hypertension and diabetes, hyperlipidemia of all subjects, measured the height, weight, SBP, DBP,detection the TCHO, LDL-c, FPG and other biochemical indexes.each subject underwent measurements of carotid WSS and CCA-IMT using carotid ultrasonography, white matter hyperintensities(WMH) using magnetic resonance imaging, and Mini-Mental State Examination(MMSE), calculate the the percentage of WMH and WSS% according to the formula.Results:1.The compare of white matter lesions, MMSE score and maximum CCA-IMT in m WSS group.1) The WMH were 11.29±2.99,8.64±3.03,6.58±2.78 in the low mean WSS tertile group, middle mean WSS tertile group and high mean WSS tertile group,the WMH in high tertile group were lower than those in low and middle tertile group,the difference was statistically significant(P<0.01).The WMH% were 0.80±0.21,0.62±0.22,0.46±0.20 in the low mean WSS tertile group, middle mean WSS tertile group and high mean WSS tertile group, the WMH in high tertile group were lower than those in low and middle tertile group,the difference was statistically significant(P<0.01).2) The MMSE score were 22.53±1.92?23.87±2.73 and 25.29±2.81 in the low mean WSS tertile group, middle mean WSS tertile group and high mean WSS tertile group, the MMSE score in high tertile group were higher than those in low and middle tertile group,the difference was statistically significant(P<0.01).3) The maximum common carotid arteries intima-media thickness(CCA-IMT) were 1.58±0.32?1.44±0.30 and 1.34±0.25 in the low mean WSS tertile group, middle mean WSS tertile group and high mean WSS tertile group, the CCA-IMT in high tertile group were lower than those in low and middle tertile group,the difference was statistically significant(P<0.01).2.The compare of white matter lesions, MMSE score and maximum CCA-IMT in p WSS group.1) The WMH were 11.46±3.14?8.46±2.84 and 6.60±2.66 in the low peak WSS tertile group, middle peak WSS tertile group and high peak WSS tertile group, the WMH in high tertile group were lower than those in low and middle tertile group,the difference was statistically significant(P<0.01).The WMH % were 0.8±0.22?0.61±0.21 and 0.47±0.19 in the low peak WSS tertile group, middle peak WSS tertile group and high peak WSS tertile group, the WMH% in high tertile group were lower than those in low and middle tertile group,the difference was statistically significant(P<0.01).2) The MMSE score were 22.86±2.53?23.79±2.47and25.04±2.83 in the low peak WSS tertile group, middle peak WSS tertile group and high peak WSS tertile group, the MMSE score in high tertile group were higher than those in low and middle tertile group,the difference was statistically significant(P<0.01).3) The maximum common carotid arteries intima-media thickness(CCA-IMT) were 1.59±0.29?1.45±0.31 and 1.32±0.25 in the low peak WSS tertile group, middle peak WSS tertile group and high peak WSS tertile group, the CCA-IMT in high tertile group were lower than those in low and middle tertile group,the difference was statistically significant(P<0.01).3.The correlation analysis of WSS and WMH, WMH, MMSE score, maximum percentage CCA-IMT1) WMH?WMH% and CCA-IMT were significant negatively correlated with mean WSS(r=-0.576,-0.576,-0.364,p<0.01),MMSE score were significant positively correlated with mean WSS(r=0.440,p<0.01).2) WMH ?WMH% and CCA-IMT were significant negatively correlated with peak WSS(r=-0.576,-0.574,-0.326,p<0.01),MMSE score were significant positively correlated with peak WSS(r=0.328,p<0.01).4.The correlation analysis of CCA-IMT and WMH, the largest percentage of WMH and MMSE scores1) WMH and WMH% were significant positively correlated with CCA-IMT(r=0.457,0.443,p<0.01),MMSE score were significant negatively correlated with CCA-IMT(r=-0.303,p<0.01).5.The correlation analysis of WMH, WMH percentage and MMSE scores1) WMH were significant negatively correlated with MMSE score(r=-0.453,p<0.01);WMH % were significant negatively correlated with MMSE score(r=-0.461,p<0.01)?6.The multiple linear stepwise regression analysis of WMH, WMH% and MMSE score and related effects1) Independent variables include mean wall shear stress, age, sex, education, current smoking, alcohol consumption, blood pressure, blood lipids, fasting plasma glucose, and common carotid intima-media thickness.For change ratio of WMH, there were statistically significant results for mean WSS(?=-0.439,t=-10.243,P<0.01), education(?=-0.134,t=-3.376,P<0.01), acohol consumption(?=0.084,t=2.161,P=0.031),SBP(?=0.141,t=3.511,P<0.01),TG(?=0.186,t=4.591,P<0.01)and CCA-IMT(?=0.233,t=5.076,P<0.01).For change ratio of WMH%, there were statistically significant results for mean WSS(?=-0.442,t=-10.015,P<0.01), education(?=-0.125,t=-3.056,P<0.01), acohol consumption(?=0.089,t=2.227,p=0.027),SBP(?=0.112,t=2.707,P<0.01),TG(?=0.152,t=3.654,P<0.01) and CCA-IMT(?=0.232,t=4.910,P<0.01).For change ratio of MMSE score, there were statistically significant results for mean WSS(?=0.329,t=7.781,P<0.01), education(?=0.534,t=13.666,P<0.01)and HDL-c(?=0.078,t=2.009,p=0.045).2) Independent variables include peak wall shear stress, age, sex, education, current smoking, alcohol consumption, blood pressure, blood lipids, fasting plasma glucose, and common carotid intima-media thickness.For change ratio of WMH, there were statistically significant results for peak WSS(?=-0.426,t=-10.119,P<0.01), education(?=-0.130,t=-3.288,P<0.01), SBP(?=0.121,t=3.015,P<0.01),TG(?=0.194,t=4.804,P<0.01) and CCA-IMT(?=0.262,t=5.817,P<0.01).For change ratio of WMH%, there were statistically significant results for peak WSS(?=-0.432,t=-9.981,P<0.01), education(?=-0.121,t=-2.975,P<0.01),SBP(?=0.092,t=2.227,p=0.027),TG(?=0.164,t=3.948,P<0.01) and CCA-IMT(?=0.261,t=5.625,P<0.01).For change ratio of MMSE score, there were statistically significant results for peak WSS(?=0.207,t=4.769,P<0.01), education(?=0.533,t=13.003,P<0.01)and CCA-IMT(?=-0.128,t=-2.743,P<0.01).Conclusion:Carotid WSS was independently associated with brain WMLs and cognitive impairment in the oldest old. |
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