The February 2016 edition of Biological Psychiatry focused on the neurohormone oxytocin and its effects on both normal and abnormal human behavior as well as its potential role in the treatment of psychiatric disorders. This is apropos given that oxytocin has been described as the “love hormone” and Valentine’s Day is right around the corner, but oxytocin is involved in much more than attachment. It also seems to play a role in motivating aggressive behavior against people who were not part of the group.
Oxytocin in the hypothalamus supports and enables people to like and empathize with others who are part of the same group, to comply with group norms of behavior, and to cooperate to with others from the group, including cooperating with them to attack or defend against perceived attacks from those outside the group.
Several genes are associated with reduced or increased oxytocin function in humans, these include the gene for the oxytocin receptor (OXTR) and for oxytocin itself (OXT, neurophysin1), as well as a gene for an enzyme that plays a role in hormone secretion (CD38) including oxytocin secretion.
Most of the human studies have focused on polymorphisms of the receptor and CD38 gene.
In general reduced oxytocin function is associated with impaired attachment in child-rearing and perhaps in romantic relationships. Reduced oxytocin function is also associated with less capacity to empathize or imagine what others are thinking in social situations as well as with less willingness to work cooperatively with others to achieve altruistic goals.
In addition, more efficient oxytocin function seems to play a key role in protecting people from the negative effects of stressful situations when in the presence of social support. Those with more efficient oxytocin function are much less vulnerable to stress in such situations whereas those with less efficient oxytocin show minimal reductions in stress when they receive social support.
It has been suggested that oxytocin administration might help in those conditions where prosocial behavior seems impaired, including borderline personality disorder, autism spectrum disorders, and schizophrenia.
As if to illustrate the complexity of oxytocin affects to counteract the simplistic notion of oxytocin as “the romance hormone” one of the articles cited a study on the effects of oxytocin administration to male behavior in relation to attractive women.
As you can see, when men who were in a stable relationship with another woman were given oxytocin they withdrew from attractive women. There was no effective oxytocin on single men.
Another article notes that oxytocin’s effect in motivating behavior seems to take place through the dopamine reward system of the brain, which may explain various types of relationship or sexual “addictive” behavior in humans.
In an accompanying editorial, Dr. Thomas Insel notes the difficulties that have been encountered with trying to come up with pharmacologic agents that modulate the oxytocin system. Whereas oxytocin itself can be administered intravenously (it is used to induce labor in women) and intranasally it has very brief effects which significantly limits its use for most purposes. And efforts to come up with oxytocin analogs have so far been less than successful.
Biological Psychiatry — February 1, 2016 Volume 79 Number 3