轻度Alzheimer’s病患者血浆氨水平对脑脊液β-淀粉样蛋白含量及认知功能的影响

Effect of plasma ammonia on β-amyloid of CSF and cognitive function in mild Alzheimer's disease

目的探讨轻度Alzheimer’s病(AD)患者血浆氨水平对CSFβ-淀粉样蛋白(Aβ)含量及认知功能的影响。方法以本院收治的108例轻度AD患者(MMSE≥16分)和47名志愿者(正常对照组)为研究对象,行认知功能评估及血浆氨检测。轻度AD患者根据血浆氨水平分为血浆氨正常组(ADA-组)、血浆氨升高组(ADA+组)。检测AD患者CSF的Aβ42、Aβ40、总tau和磷酸化tau水平并进行比较。结果与正常对照组比较,ADA-组及ADA+组MMSE、蒙特利尔认知评估量表(MoCA)评分显著降低(均P<0.001),ADA-组MoCA评分显著高于ADA+组(P<0.001)。ADA+组血浆氨水平显著高于ADA-组及正常对照组(均P<0.001)。ADA+组Aβ42、Aβ40水平显著低于ADA-组(t=2.29,P=0.024;t=2.72,P=0.008)。ADA+组血浆氨水平与MoCA评分(r=-0.47,P<0.001)及CSF Aβ42水平(r=-0.63,P<0.001)呈显著负相关。CSF Aβ42水平在血浆氨水平和认知功能之间存在显著中介效应,中介效应占总效应的百分比为45.94%。结论部分AD患者存在血浆氨升高,高血氨可能通过降低CSF Aβ42水平,导致Aβ42沉积形成斑块,使认知障碍进一步加重。

Objective To investigate effect of plasma ammonia on β-amyloid(Aβ)of CSF and cognitive function in mild Alzheimer's disease(AD).Methods A total of 108 mild AD patients admitted to our hospital and 47 volunteers(HC group)were studied,the cognitive function were measured and plasma ammonia were detected.The mild AD patients were divided into normal ammonia group(ADA-group)and hyperammonemia group(ADA+group)by the plasma ammonia level.The level of Aβ42,Aβ40,total tau and phosphorylated tau protein in CSF of AD patients were detected,and the results were compared.Results Compared with HC group,the MMSE and Montreal Cognitive Assessment(MoCA)in the ADA-group and ADA+group were significantly lower(all P<0.001).The MoCA of ADA+group was significantly lower than that of ADA-group(P<0.001).The plasma ammonia of ADA+group were significantly higher than those of ADA-group and HC group(all P<0.001).The levels of Aβ42 and Aβ40 in ADA+group were significantly lower than those of ADA-group(t=2.29,P=0.024;t=2.72,P=0.008).In ADA+group,the plasma ammonia level was negatively correlated with the MoCA score(r=-0.47,P<0.001)and level of Aβ42 in CSF(r=-0.63,P<0.001).The level of Aβ42 played a partial mediating role between the plasma ammonia level and cognitive function,and mediating effect accounted for 45.94% of the total effect.Conclusion The plasma ammonia level is elevated in some AD patients,high plasma ammonia level may reduce the Aβ42 level in CSF,contributes to Aβ42 deposition which forms the amyloid plaques,ultimately aggravates cognitive impairment.