3.2. Relations to Age Obtained through Factor Analyses and SEM Modelling
REGRESSION, INFLAMMATION, OXIDATIVE STRESS
To validate the above-obtained associations to age, we applied SEM modelling, as this method can better elucidate possible relations with age, if they exist.
CFA was performed on data from the total dataset of 19 variables as a first step. A three-factor solution was found to be optimal with respect to fit indices. However, the structural factors were hard to interpret, and the five biomarkers related to ageing appeared to be spread over the factors.Nevertheless, when analysing the latter five biomarkers specifically, a clear two-factor structure with a good fit was found. ICAM-1 and adiponectin formed one factor (called “Alfa”) and SCF and osteoprotegerin another (called “Beta”). However, leptin had insignificant loadings in both factors. The correlation between “Alfa” and “Beta” was insignificant. In a final structural three-factor model, “Alfa”, “Beta” and “Gamma” (representing age) were analysed, and the hypothesis that “Alfa” and “Beta” were independently related to “Gamma” was tested. As a conclusion from the factor analysis above, leptin was excluded from the model. The relation between leptin and age was also insignificant. The model fit was good: Chi-square = 3.43, df = 3, In the model, “Alfa” represents a factor underlying ICAM-1 and adiponectin, and “Beta” represents a factor underlying SCF and osteoprotegerin. The Beta values (for “Alfa” 0.70 and for “Beta” 0.32) are significant, and “Alfa” and “Beta” are unrelated (r = 0.18, t = 1.16, To validate or interpret the meanings of the factors “Alfa” and “Beta”, their relations to the other 14 measures of the database were examined by means of linear regression analyses. The results are presented in As can be seen from the table, there are some variables separating “Alfa” and “Beta”. Compared to “Alfa”, “Beta” has stronger relations to TWEAK, endostatin and CRP, it and appears to express, among other things, the degree of inflammation. On the other hand, “Alfa” has stronger relations to age, NT-pro-BNP and copeptin, and it might reflect, among other things, ongoing oxidative stress [The results for each of the five selected biomarkers before and after the intervention are presented below, and the ANCOVA analyses with levels of the five selected biomarkers before and after the intervention are shown in 