Previous research indicates that 5-HTTLPR variants exert their effect on a number of phenomena in a gender-based manner, and this is true also in interaction with environmental stressors. Although several studies did not consider gender or produced inconsistent results, a general pattern of findings indicates that the 5-HTTLPR s allele has opposite effects in the two genders, increasing risk of depression in females but acting as a protective factor or having no effect in males, and the same pattern is observable also when interaction with stressful life events is considered.61, 62, 63, 64 A recent systematic review of 78 papers on gender differences in the effect of 5-HTTLPR in affective spectrum disorders concluded that in interaction with stressful events presence of the s allele is associated with an increased risk of depressive symptoms, depression, trait or symptomatic anxiety and internalising behaviour in women, and with aggression, conduct disorder and externalising behaviours in men.63 Gender differences in the effects of 5-HTTLPR were also reported in functional imaging65 and resting-state electroencephalogram studies.66 Specifically, greater synchronisation of regional neural organisation and the modulation
