Investigation of higher-order factors of personality using resting-state functional connectivity and personality measure scale

Abstract

In chapter 2, we conducted a network analysis on depression and anxiety symptoms of depression with the view that the presence of certain symptoms induces expression of correlated symptoms. In the results, depressive symptoms and anxiety symptoms were intertwined, the cognitive symptoms of depression caused anxiety symptoms, and the anxiety symptoms were found to cause somatic symptoms of depression (Study I). In addition, not only depression and anxiety symptoms but also emotional adversities, social anxiety, substance addiction, trauma-related symptoms, and support systems were analyzed together. Furthermore, we investigated how the integrity of the entire network is degraded if the effect of each variable on the entire network is intervened. The analysis showed that interventions in the experience of verbal abuse, social anxiety, concentration problems, and suicidal ideation might have the strongest influences on changes in the network topology (Study II). In Chapter 3, we analyzed the items of questionnaires that measured personality and the resting-state functional connectivity (RSFC). First, we conducted network analysis of the items that measure personality. Items belonging to the same factor appear to be relatively well clustered, but significant associations have been observed between different factors. These findings were not consistent with the theoretical assumptions of personality models based on factor analysis. (Study III). Furthermore, it was noted that five-factor personality models are determined by factor analysis of adjectives extracted from a dictionary. We tried to figure out the factors of personality by considering not only the items that measure personality based on the five-factor model of personality but also the RSFC. This analysis showed that significant factors had the strongest correlations with factors called higher-order factors of personality. In other words we were able to derive novel personality factors that considered both the RSFC and the paper-delivered personality measurement items (Study IV).