A01

• The limbic system, including the amygdala, hypothalamus, and parts of the hippocampus, are associated with emotional behaviours and aggression. The amygdala's reactivity is a predictor of aggression; heightened activity correlates with increased aggression. Studies show that amygdala response spikes during provocation, and benzodiazepine intake reduces both amygdala activity and subsequently aggression.
• Serotonin, known for inhibitory effects, influences behavioural control. Normal serotonin levels in the orbitofrontal cortex (OFC) correlate with enhanced self-control, while deficiency leads to impulsivity and aggression. Research has found lower serotonin breakdown products in impulsive offenders, suggesting a link between serotonin levels and aggression.
• Testosterone, a male hormone, is associated with aggression. Men exhibit higher aggression levels, and testosterone peaks correlate with aggression toward males. Castration studies show reduced aggression in animals, reversed by testosterone injections. Research found a positive correlation between testosterone and aggression in male offenders.

  Progesterone, a female hormone, influences aggression in women. Low progesterone levels during menstruation correlate with increased aggression.