Alzheimer`s disease is the most common neurodegenerative disease, and the number of the patient is increasing sharply. But the molecular mechanisms of Alzheimer`s disease(AD) has not been discovered. It is known that acceleration of aging processes is one of the major factor of the Alzheimer`s disease because of similarity of symptoms and functions.
It is unclear how much aging processes have an effect on Alzheimer`s disease. In this research, we attempted to identify the influence level of aging processes to the late-onset Alzheimer`s disease. To do this, we applied differential co-expression analysis. Differential co-expression analysis is usually used to characterize changes of functional relationship between genes(or proteins) as the condition is changing. Therefore, it helps to analyze gene sets(modules) that have similar functional relation changes. We adopted this method to brain gene expression profiles both aging process(young vs. old) and Alzheimer`s disease pathogenesis(old vs. AD affected), and found modules that reflects the changes of each condition. Then, by using functional similarity, we identified aging-related AD modules, and aging-not-related AD modules.
To check the influences aging-related AD modules and not-aging-related AD modules to Alzheimer`s disease, we adopted classification method. For comparing the performance between module features, we used the Area Under ROC curve(AUC) value.
The AUC value of overall aging-related AD modules showed weak difference compared with aging-not-related AD modules. However, in the case of modules which have specific proteins(genes), the AUC value showed differences in logistic classifier.(AUC of age-related AD modules with APP interactome: 0.85, AUC of not-age-related modules: 0.7175 / AUC of age-related AD modules with tau interactome: 0.974, AUC of not-age-related modules with tau interactome: 0.86). Therefore, in Alzheimer`s disease pathogenesis, specific protein related aging processes might be ...