Effect of plasma ammonia on β-amyloid of CSF and cognitive function in mild Alzheimer's disease / 临床神经病学杂志

ABSTRACT

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.