| Objective:Despite numerous studies on the relationship between brain-derived neurotrophic factor(BDNF)and Alzheimer’s disease(AD),BDNF has not been established as a diagnostic marker for AD.To provide a different perspective,this study aims to investigate the relationship between AD and serum levels of mature BDNF(mBDNF),precursor BDNF(proBDNF),the ratio of mBDNF to proBDNF(M/P),and evaluate their value in assisting the diagnosis of AD.Method:In this cross-sectional observational study,a total of 126 eligible subjects were assigned to either the AD group(n=62)or the healthy control(HC,n=64)group.The subjects’age,years of education,Mini-Mental State Examination(MMSE)scores,and duration of illness for AD patients were collected.Enzyme-linked immunosorbent assay(ELISA)was used to measure the serum levels of mBDNF and proBDNF in the subjects.Differences in mBDNF and proBDNF levels between the AD and HC groups were analyzed separately for two different age groups(61-70 years and 71-80 years)and gender groups.The experimental results were expressed as mean±standard deviation or median,and statistical analysis was performed using data statistical analysis software with methods such as independent sample t-test,chi-square test,Fisher’s exact test,logistic regression,and multiple linear regression.Significant levels(p-values),regression coefficients(β),standard errors(SE),and memory fit coefficients(R~2)were obtained as indicators.Receiver operating characteristic(ROC)curves were plotted,and the area under the curve(AUC)was calculated with a 95%confidence interval(CI)to determine the risk of AD.Results:The serum concentration of proBDNF was significantly higher in the AD group(4140.94 pg/ml)than in the HC group(2606.94 pg/ml,p<0.01).MMSE was significantly correlated with proBDNF(p<0.01,r=-0.686)and M/P(p<0.01,r=0.595),but not with mBDNF.There were significant differences in proBDNF levels between AD and HC groups in both the 61-70 age group and the 71-80 age group(p<0.0001),but no significant differences in mBDNF levels.There were no significant differences in mBDNF and proBDNF levels between males and females in either the AD or HC group.Logistic regression analysis showed that mBDNF had a significant negative impact on the outcome(β=-0.005,SE=0.002,p=0.022),while M/P had a significant negative impact on the outcome(β=-37.428,SE=7.085,p<0.0001),and proBDNF had a significant positive impact on the outcome(β=0.002,SE=0.0001,p<0.0001).Multiple linear regression analysis showed that MMSE score was a significant predictor of proBDNF(R~2=0.451,p<0.0001,β=-101.728)and M/P(R~2=0.330,p<0.0001,β=0.004),but not of mBDNF(R~2=0.088,p=0.271).The AUCs of serum mBDNF,proBDNF,and M/P were 0.596(95%CI:0.496-0.696),0.896(95%CI:0.844-0.949),and 0.856(95%CI:0.793-0.920),respectively.The weighted ROC analysis showed that the AUC for the combination of proBDNF and M/P was 0.901(95%CI:0.850-0.953).Conclusion:Based on our analysis,we found that the serum levels of proBDNF in AD patients were significantly higher than those in the HC group and were significantly correlated with MMSE scores and the M/P ratio,while the levels of mBDNF were not associated with AD.Gender had no effect on the levels of mBDNF and proBDNF,while the difference in proBDNF levels among different age groups was significant,and the difference in mBDNF levels varied according to age groups.Logistic regression and multiple linear regression analyses showed that proBDNF had a significant positive effect on the diagnosis of AD,while mBDNF and M/P had a negative effect.Weighted ROC analysis found that the diagnostic accuracy of serum proBDNF and M/P ratio was higher than that of serum mBDNF,and the combined use of proBDNF and M/P ratio could improve the diagnostic accuracy of AD. |
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