Objectives: Numerous studies have shown associations between an on-going depression and elevated serum levels of the acute-phase reactant C-reactive protein (CRP). Also, in suicidal behaviour, a proinflammatory state has been suggested to be of importance for the pathophysiology. There is a genetic susceptibility to suicidal behaviour, but studies with respect to genes related to inflammation are sparse. We have previously reported an association between a polymorphism located in the CRP gene, +1444C>T (rs1130864), and the personality trait impulsiveness in women assessed using the Karolinska Scales of Personality. The present study aims to replicate these results in suicide attempters and examine whether the polymorphism is associated with suicidal behaviour.
Materials and methods: The +1444C>T polymorphism was genotyped in suicide attempters from two cohorts (a total of 106 patients) and healthy controls (n=517).
Results: We could replicate our previous finding, as the +1444T allele was associated with higher scores in the Karolinska Scales of Personality factor extraversion and its subscale impulsiveness in one of the patient cohorts. Furthermore, the +1444T allele was significantly more common among suicide attempters compared with the +1444C allele.
Conclusion: The present results lend further support to the relevance of inflammation for suicidal behaviour. The association between the polymorphism and personality trait impulsiveness reinforces our hypothesis of the importance of immune-related genes also for normal mental functions such as personality traits. Given the fact that impulsiveness is a well-known risk factor for suicidal behaviour, we further hypothesize that the polymorphism studied may in part explain this relationship.