Relationship between serotonin and the Temperament and Character Inventory

The unified biosocial theory of personality, proposed by Cloninger, conceptualises personality as a combination of heritable, neurobiologically based traits (temperament dimensions), and traits reflecting sociocultural learning (character dimensions). The temperament dimensions are thought to be related to activity in specific central neurotransmitter systems. The relationship of the dimensions of the Temperament and Character Inventory, particularly harm avoidance (HA), and platelet 5-HT₂ receptor sensitivity was investigated in a sample of undergraduate student volunteers (N=49). Serotonin-receptor binding results in Ca²⁺ release from intracellular stores. The concentration of serotonin required to produce half maximal Ca²⁺ response (EC₅₀) is indicative of 5-HT₂ receptor sensitivity such that the lower the EC₅₀ serotonin concentration, the greater the 5-HT₂ receptor sensitivity. A significant inverse correlation was found between HA and EC₅₀ (r=-0.644, P<0.001). Self-directedness was also significantly correlated with EC₅₀ (r=0.391, P=0.005). Novelty seeking, a personality trait similar to sensation seeking, was not significantly correlated with serotonin. Copyright (C) 1999 Elsevier Science Ireland Ltd.