Understanding Aggression: Biological Correlates and Associations with Suicidal Behavior

Aggression is a broad term referring to any behavior intended to harm another person who is motivated to avoid being harmed (*Baron & Richardson, 1994; *Anderson & Bushman, 2002). Given its well-known heterogeneity, and aiming at increasing specificity in its understanding (S*wogger et al., 2014), researchers have examined biological correlates of aggressive behavior and proposed distinct categories of aggression with the bimodal typology of emotionally charged, uncontrolled, impulsive, reactive aggression (RA) vs planned, controlled, unemotional, premeditated, proactive aggression (PA) being the most consistent and reliable classification (*Dodge & Coie, 1987; *Crick & Dodge, 1996; *Houston et al., 2003).
A large body of evidence suggests that aggression is associated with suicidal behavior (**Mann et al., 1999; **Soloff et al., 2000; *Oquendo & Mann, 2001; *Placidi et al., 2001; **Stanley et al., 2001; *Van Heeringen, 2003; **Oquendo et al., 2004; **Dumais et al., 2005; *Sher et al., 2005; *Brodsky et al., 2006; **Zalsman et al.,

Despite the leading hypothesis that aggression is associated with low baseline cortisol (**Poustka et al., 2010; *van Goozen et al., 2007) and high cortisol reactivity (*Gerra et al., 2001), a 2010-metanalysis claimed that there is no association between cortisol (re)activity and aggression in adolescents (*Alink et al., 2008). Characterizing aggression into RA and PA subtypes is postulated to be a possible approach to overcome this inconsistency; a hypothesis supported by the finding that RA, but not PA, was associated with elevated cortisol response during a stress task in prepubertal children (*Lopez-Duran et al., 2009), and in adolescent males (**van Bokhoven et al., 2005) as