Dopamine activates the reward circuit, helping to make love a pleasurable experience similar to the euphoria associated with use of cocaine or alcohol.
Scientific evidence for this similarity can be found in many studies, including one conducted at the University of California, San Francisco, and published in 2012 in .
Many theories of love, said Schwartz and Olds, propose that there is an inevitable change over time from passionate love to what is typically called compassionate love—love that is deep but not as euphoric as that experienced during the early stages of romance.
That does not, however, mean that the spark of romance is quenched for long-married couples.
That study reported that male fruit flies that were sexually rejected drank four times as much alcohol as fruit flies that mated with female fruit flies.
“Same reward center,” said Schwartz, “different way to get there.” Other chemicals at work during romantic love are oxytocin and vasopressin, hormones that have roles in pregnancy, nursing, and mother-infant attachment.“We know that primitive areas of the brain are involved in romantic love,” said Olds, an HMS associate professor of psychiatry at Boston’s Massachusetts General Hospital, “and that these areas light up on brain scans when talking about a loved one.These areas can stay lit up for a long time for some couples.” When we are falling in love, chemicals associated with the reward circuit flood our brain, producing a variety of physical and emotional responses—racing hearts, sweaty palms, flushed cheeks, feelings of passion and anxiety.More than 20 years ago, the biological anthropologist Helen Fisher studied 166 societies and found evidence of romantic love—the kind that leaves one breathless and euphoric—in 147 of them.This ubiquity, said Schwartz, an HMS associate professor of psychiatry at Mc Lean Hospital in Belmont, Mass., indicates that “there’s good reason to suspect that romantic love is kept alive by something basic to our biological nature.” In 2005, Fisher led a research team that published a groundbreaking study that included the first functional MRI (f MRI) images of the brains of individuals in the throes of romantic love.This circuit is considered to be a primitive neural network, meaning it is evolutionarily old; it links with the nucleus accumbens.Some of the other structures that contribute to the reward circuit—the amygdala, the hippocampus, and the prefrontal cortex—are exceptionally sensitive to (and reinforcing of) behavior that induces pleasure, such as sex, food consumption, and drug use.In addition to the positive feelings romance brings, love also deactivates the neural pathway responsible for negative emotions, such as fear and social judgment.These positive and negative feelings involve two neurological pathways.Richard Schwartz and Jacqueline Olds know a lot about love.These Harvard Medical School (HMS) professors and couples therapists study how love evolves and, too often, how it collapses.