Evaluation of the Diagnostic and Predictive Value of Glutamic Acid Decarboxylase, Zinc Transporter 8 Serum Levels in Alzheimer's Disease.

BACKGROUND: Identification of validated peripheral biomarkers for Alzheimer's Disease, leading to an early diagnosis of the disease, would be valuable for predicting progression and targeted therapeutics. In this regard, serum levels of GADA, ZnT8A, Zn, vitamin D, and leukocyte expression of brain-derived neurotrophic factor (BDNF) gene were investigated in Alzheimer's patients and control group. METHODS: Serum levels of GADA, ZnT8A, Zn, and vitamin D and leukocyte expression of the BDNF gene were evaluated in 40 AD patients and 40 control cases. The diagnostic value of investigated factors was examined with the receiver operating characteristic (ROC). RESULTS: The results showed significant differences of p < 0.0001, p < 0.0001, and p = 0.0006 between AD patients and control individuals in GADA, Zn, and ZnT8A serum levels, respectively. No significant difference was observed in the serum concentration of vitamin D between AD patients and control cases (p = 0.2993). The expression level of the BDNF gene in AD patients was different from control cases, but it was not statistically significant (p > 0.05). Moreover, ROC curve analysis disclosed a diagnostic potency for serum levels of GADA, Zn, and ZnT8A for AD with an area under the ROC curve of > 0.7 (p < 0.0001, p < 0.0001, and p = 0.0007, respectively). CONCLUSIONS: The results demonstrated the higher serum levels of GADA and ZnT8A and lower serum concentrations of Zn in the patient group. Therefore, these parameters can be discussed as possibly diagnostic in AD cases.

Evaluation of the Serum Dkk-1, Tenascin-C, Oxidative Stress Markers Levels and Wnt Signaling Pathway Genes Expression in Patients with Alzheimer's Disease.

Early diagnosis of Alzheimer's disease (AD) using potential biomarkers may help with implementing early therapeutic interventions, monitoring, and ultimately disease treatment. The current study aimed to evaluate serum levels of DKK-1, TNC, and oxidative stress markers, as well as analyzing the expression of LRP6, GSK3A, and GSK3B genes in patients with AD. Serum levels of DKK-1, TNC, TOS, TAC, and MDA were measured in 40 AD patients and 40 healthy individuals. Additionally, the relative expressions of LRP6, GSK3A, and GSK3B genes in whole blood were evaluated. Receiver operating characteristic (ROC) analysis was used to investigate the incremental diagnostic value of each factor in the study groups. Mean serum levels of DKK-1, TNC, TOS, TAC, and MDA were significantly higher in the AD group compared to the healthy group (p < 0.001). Moreover, a significant difference was observed in the expression of LRP6 and GSK3A genes (p < 0.001) between patients and healthy groups. However, the expression of GSK3B did not significantly differ between the two groups (p > 0.05). With considerable sensitivity and specificity, ROC analysis demonstrated the diagnostic efficacy of DKK-1 and TNC serum levels in AD within an area under the ROC curve of ≥ 0.98 (p ˂ 0.001). The results showed that evaluating serum levels of DKK-1 and TNC, as well as assessing the expression of LRP6, could be utilized for diagnosis and monitoring of AD patients.