Dopamine May Play Role in Human Bonding

A new study shows, for the first time, that dopamine may play a significant role in human bonding and relationships. Dopamine is a neurotransmitter integrally involved in the brain’s reward system.

The findings, published in the journal Proceedings of the National Academy of Sciences, have important implications for the treatment of postpartum depression as well as disorders of the dopamine system such as Parkinson’s disease, addiction, and social dysfunction.

The study, which involved 19 mothers and their infants, used two types of brain scans simultaneously — functional magnetic resonance imaging (fMRI) and positron emission tomography (PET).

The researchers focused on the neurotransmitter dopamine, a chemical that acts in various brain systems to spark the motivation necessary to work for a reward. The researchers compared the mothers’ levels of dopamine to their degree of synchrony with their infants as well as to the strength of the connection within the brain’s medial amygdala network. This brain network helps support social affiliation.

“We found that social affiliation is a potent stimulator of dopamine,” said researcher Dr. Lisa Feldman Barrett, Distinguished Professor of Psychology at Northeastern University. “This link implies that strong social relationships have the potential to improve your outcome if you have a disease, such as depression, where dopamine is compromised.”

“We already know that people deal with illness better when they have a strong social network. What our study suggests is that caring for others, not just receiving caring, may have the ability to increase your dopamine levels.”

Before performing the scans, the researchers videotaped the mothers at home interacting with their babies and applied measurements to the behaviors of both to determine their degree of synchrony. They also recorded the infants playing on their own.

While in the brain scanner, each mother viewed footage of her own baby at solitary play as well as an unfamiliar baby at play while the researchers measured dopamine levels, with PET, and tracked the strength of the medial amygdala network, with fMRI.

The mothers who were more synchronous with their own babies showed both an increased dopamine response when viewing their child at play and stronger connectivity within the medial amygdala network.

“Animal studies have shown the role of dopamine in bonding but this was the first scientific evidence that it is involved in human bonding,” said Barrett. “That suggests that other animal research in this area could be directly applied to humans as well.”

While the findings are still “cautionary,” they have the potential to reveal how the social environment impacts the developing brain, said Barrett.

“Infants are completely dependent on their caregivers. Whether they get enough to eat, the right kind of nutrients, whether they’re kept warm or cool enough, whether they’re hugged enough and get enough social attention, all these things are important to normal brain development,” said Barrett.

“Our study shows clearly that a biological process in one person’s brain, the mother’s, is linked to behavior that gives the child the social input that will help wire his or her brain normally. That means parents’ ability to keep their infants cared for leads to optimal brain development, which over the years results in better adult health and greater productivity.”

“People’s future health, mental, and physical, is affected by the kind of care they receive when they are babies. If we want to invest wisely in the health of our country, we should concentrate on infants and children, eradicating the adverse conditions that interfere with brain development,” said Barrett.

Source: Northeastern University