It can also, as discovered recently by researchers, intensify men's memories of their mother's affections during childhood.
The study, which was conducted by researchers at the Seaver Autism Center for Research and Treatment at Mount Sinai School of Medicine, set out to determine whether oxytocin, which is known to regulate attachment and social memory in animals, is also involved in human attachment memories.
They conducted a randomized, double-blind, placebo-controlled, cross-over trial, giving 31 healthy adult men oxytocin or a placebo delivered nasally on two occasions.
Prior to administering the drug or placebo, the researchers measured the men's attachment style. About 90 minutes after administering the oxytocin or the placebo the researchers assessed participants' recollection of their mother's care and closeness in childhood.
They found that men who reported having fond memories of their mothers during the first assessment remembered them even more fondly after they received oxytocin, compared to when they received placebo.
However, men who reported negative feelings associated with their mothers during the first assessment remembered them even more negatively after receiving oxytocin, compared to when they received placebo.
The researchers found these results were not due to more general effects of oxytocin on mood or well-being.
"These results may seem surprising because researchers have assumed that the neuromodulator oxytocin has ubiquitous positive effects on social behavior and social perception in humans," said Jennifer Bartz, PhD, Assistant Professor, Psychiatry, Mount Sinai School of Medicine, and lead author of the study.
The study changed how many researchers view the hormone, long thought to simply produce positive feelings.
"The fact that oxytocin did not make all participants remember their mother as more caring, but in fact intensified the positivity or negativity of the men's pre-existing memories, suggests that oxytocin plays a more specific role in these attachment representations," said Bartz.
Bartz and the study authors said they do not know whether oxytocin, when administered in drug form, increases a person's ability to accurately recall their mother's affections in childhood, or sets in motion a biased search for memories that support their more general beliefs about close relationships.
The ability to bond with our caregivers early in life has long been thought to be critical to survival because these bonds insure caregiver protection for the otherwise defenseless infant.
"We know very little about the biological mechanisms that support human attachment bonds, but understand that oxytocin regulates attachment in animals, and plays a specific role in forming social memories," said Bartz.
"Our study suggests that oxytocin may similarly play a key role in human attachment by modulating these early memories of mom."
The study was published Monday in Proceedings of the National Academy of Sciences.
