The relationships of temperament, character, and depressive symptoms with paranoid ideation

This study investigated i) the relationship of temperament and character with paranoid ideation over age in adulthood ii) the association of explosive temperament profile with the development of character dimensions self-directedness and cooperativeness, and whether this association is modified by social support and attachment security iii) the co-occurrence of depressive symptoms with paranoid ideation from late adolescence to middle age in the general population. The participants (n = 2028, 2137, and 2109 in Studies I‒III) were selected from the prospective Cardiovascular Risk in Young Finns Study, which started in 1980. Paranoid ideation and depressive symptoms were assessed at several time points over a 20-year follow-up in 1992‒2012. Temperament and character, social support, and attachment security were measured multiple times between 1997‒2012. We used multilevel models for repeated measurements, which were controlled for participants’ age, gender, and socioeconomic status both in childhood and adulthood. The results revealed that single temperament dimensions of high novelty seeking, high harm avoidance and low reward dependence and also explosive temperament profile (consisting of high novelty seeking, high harm avoidance, and low reward dependence) were related to a higher level of paranoid ideation in adulthood. These associations appeared to be mediated by character dimensions. Specifically, high self-directedness, high cooperativeness, and low self-transcendence could protect individuals with temperament-related susceptibilities from paranoid ideation. Explosive temperament was associated with lower self-directedness and cooperativeness as compared to other temperaments, but high social support and secure attachment had a positive influence on character development in individuals with explosive temperaments. Additionally, we found that depressive symptoms were linked with the course of higher paranoid ideation, especially in late adolescence and early adulthood. Regarding various depressive subsymptoms, high negative attitude and high performance difficulties were associated with the course of more severe paranoid ideation over age in adulthood, whereas the influence of somatic symptoms became significant only after early adulthood. Finally, depressive symptoms appeared to be more strongly related to the development of trait- than state-level paranoid ideation. Specific variants of single temperament dimensions and profiles represented susceptibilities for paranoid ideation. The presence of supportive and confidential relationships was linked with more mature character (i.e. higher self-directedness and higher cooperativeness), which appeared to have a protective role against paranoid ideation in individuals with risky temperaments. The co-occurrence between depressive symptoms and paranoid ideation was especially evident in late adolescence and early adulthood. Individuals, who have temperament-related susceptibilities for paranoid ideation, might benefit from interventions, which promote the abilities to form confidential and supportive social relationships. This might help them to internalize more mature concepts about the self and interpersonal relationships, which, in turn, could enhance the self-regulation of temperament-related susceptibilities and lower the risk for paranoid ideation. Individuals with co-occurring depressive symptoms and paranoid ideation might benefit from neurocognitive rehabilitation, social skills training, and community-based treatments in order to enhance interpersonal activities and metacognitive abilities.