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Impulsivity is considered a vulnerability trait for addiction. Recently, we found trait non-planning impulsiveness measured with the Karolinska Scales of Personality was negatively correlated with dopamine D2/3 receptor availability in the ventral striatum of healthy humans. While also observed in rodents, human studies have failed to find this association with other measures of trait impulsivity. We explored whether another rodent finding, reduced ventral striatum volume with greater impulsivity, could also be observed in humans using this scale. Non-planning impulsiveness was measured in 52 healthy subjects (21 female; mean age: 33.06 ± 9.69) using the Karolinska Scales of Personality. Striatal subregion volumes, including the globus pallidus, were acquired using the Multiple Automatically Generated Templates ( MAGeT-Brain) algorithm. Although failing to support our a priori hypothesis, there was a significant sex interaction in the post-commissural putamen with impulsiveness. Exploratory analyses revealed impulsiveness was negatively correlated with post-commissural putamen volumes in males, but positively correlated in females. We replicated this finding in males in an increased sample (including all 52 previous subjects) who provided impulsiveness measured by the Temperament and Character Inventory ( n = 73; 32 female; mean age: 33.48 ± 9.75). These correlations by sex were statistically different from one another, the main finding with the Kasolinksa Scales of Personality surviving correction for multiple comparisons. While impulsivity may be related to reduced ventral striatal D2/3 receptors across sexes, males but not females may show significant reductions in post-commissural putamen volume. These findings have important implications for understanding biological markers underlying sex differences in drug addiction vulnerability. [ABSTRACT FROM AUTHOR]

Raised levels of inflammation markers have been associated with several mental disorders; however, studies regarding the relationship between inflammation or the immune system and various aspects of human behaviour are not numerous. The aim of the present study was to investigate whether an association exists between personality traits and two single nucleotide polymorphisms located in genes that are associated with the innate immune system. The studied population consisted of 42-year-old women recruited from the population registry that had been assessed by means of Karolinska Scales of Personality, a self-reported inventory. The first polymorphism, +1444C>T (rs1130864), is located in the gene coding for C-reactive protein (CRP), a marker of low-grade inflammation. The T-allele has previously been suggested to be linked to raised serum levels of CRP. The second polymorphism, Y402H (1277T>C, rs1061170), is located in the gene coding for complement factor H, an important regulator of the complement system. The C-allele has consistently been associated with age-related macular degeneration. While the +1444T allele was associated with higher scores in the personality traits impulsiveness, monotony avoidance and social desirability, the 1277C polymorphism was associated with higher scores in verbal aggression and lower scores in social desirability. In conclusion, the associations between the personality traits and the studied polymorphisms further support the possible influence of the immune system on mental functions. [ABSTRACT FROM AUTHOR]