**9.1. AVP and female human affiliation**

In contrast to the pro-aggressive effects of intranasal AVP in men, AVP induces affiliative facial motor patterns in women in response to the faces of unfamiliar women and increases the perception of the faces as friendly. This gender specific effect supports the animal work on AVP. In contrast, the AVP treatment increased anxiety in both sexes [181]. Homozygosity for the RS3 allele 334 doubles the risk of marital difficulties, and negatively influenced how the relationship was perceived by the spouse [203]. Central AVP activity may be a worthwhile target for gender specific treatments aimed at improving human pair bonds.
