We hypothesized that

the association between genotype and childhood trauma would be different for men and women. Specifically, we expected that male carriers of the low-expression MAOA variant would express higher levels of click here aggression-related behaviors than carriers of the high-expression variant, in particular in the context of early adversity. We expected an opposite pattern in females. Methods Participants A total of 432 healthy, nonsmoking participants aged between 18 and 35 participated in the study (332 women, 100 men). Participants were recruited via advertisements, flyers, and posters in the university Inhibitors,research,lifescience,medical buildings (University of Leiden, the Netherlands). Participants had to be of Western European descent Inhibitors,research,lifescience,medical (i.e., all four grandparents born in the Netherlands, Germany, France, Belgium, Luxemburg, Austria, Switzerland, Ireland, the United Kingdom, or Scandinavia). Exclusion criteria were medication use (including oral contraception) and a current depressive episode. The presence of more women than men in the current sample is useful because, unlike men, women can be either hetero- or homozygous for the MAOA genotype.

Measures Childhood trauma was measured using the 28-item version Inhibitors,research,lifescience,medical Childhood Trauma Questionnaire (CTQ) (Bernstein et al. 1997; Thombs et al. 2009). This self-report questionnaire has been validated both in clinical and in nonclinical samples. The CTQ

has five subscales (Emotional abuse, Physical abuse, Sexual abuse, Emotional neglect, and Physical neglect) and each Inhibitors,research,lifescience,medical item is rated on a Likert scale ranging from 1 (never true) to 5 (very often true). We divided participants in two groups: those who reported none/minimal-to-moderate levels of childhood trauma and those who reported moderate-to-severe levels of childhood trauma. The distinction was based on severity norm scores from a sample of North American college students (Bernstein Inhibitors,research,lifescience,medical et al. 1997), with participants scoring lower than the cutoff score of 38 assigned to the none/minimal-to-moderate levels of childhood trauma group and those scoring over 38 assigned to the moderate-to-severe levels of childhood trauma group. The Spielberger State-Trait Cediranib (AZD2171) Anger Expression Inventory (STAXI) (Van der Ploeg et al. 1982; Spielberger et al. 1983; Forgays et al. 1997) was used to measure aggression-related behaviors both as an emotional state and as a personality trait. Both versions of the STAXI consist of 10 items with a 4-point Likert scale. Cognitive reactivity was measured with the Leiden Index of Depression Sensitivity – Revised (LEIDS-R) (Van der Does 2002, 2005; Williams et al. 2008).