SALT LAKE CITY -- Hayley Madsen and Justin Hedin of Provotalk about cravings and withdrawal. They use the word "addiction."
They're not talking about a drug. They're describing being in love with each other.
Hedin - a BYU student and track athlete -- and Madsen -- a hairdresser -- met a few months ago and fell head-over-heels for each other.
"You just crave each other's company, just to be around them," Madsen said.
As scientists try to unravel the neurological basis of romantic attachment, however, they find love really is like a drug. University of Utah psychology professor Lisa Diamond -- who studies what scientists call "affectional bonds" - says researchers put people newly in love in MRI machines and scanned their brains as they looked at pictures of their partners.
The scans showed activity in the caudate nucleus and the VTA -- or ventral tegmental area. Both are dopamine-rich reward centers.
"When you're passionately involved with someone and you're looking at the face of that person, your brain is squirting out this chemical that makes that experience itself of just looking or thinking about that person inherently pleasurable and inherently rewarding," Diamond said.
"The more we learn about love the more we realize that we are wired to feel this way. We evolved to feel passionately, to want others to be near us, and I think that makes it more exciting to think that basically everything about us prepared us to feel this way."
She says these are the same areas that light up in the brains of people battling drug addictions.
"You have that same response when looking at that picture as people who are addicted to drugs when they see drug paraphernalia," Diamond said. "Just even encountering the stimuli is rewarding."
At the same time, she says, there's less activity in the amygdala, a brain structure that helps us feel fear. It's no coincidence then, that holding a partner's hand gives comfort.
In one experiment, University of Virginia psychologist James Coan scanned the brains of women while they received mild electric shocks while holding their husbands' hands, and then while holding the hands of strangers.
There was less neurological stress when holding the hands of a loved one. The better the relationship, the less the stress that showed up on the brain scans.
Diamond says while desire evolved to perpetuate the species, romantic love, it's thought, somehow evolved from the bond between infant and caretaker.
"The basic system evolved not for the purpose of getting romantic partners to stay close to one another but for getting infants to stay close to their caregivers," she said.
A baby is wired to be close to his mother or caretaker.
Diamond can spot new couples in her classes by how close they are.
"You'll see with new couples, they can't stop holding hands," she said.
She notes that love poems and prose and love songs - "Get Closer," "I Wanna Hold Your Hand," "The Nearness of You" -- often talk about proximity.
Eventually, romantic love and dopamine fade, Diamond says, and what's called the attachment system -- mediated by chemicals oxytocin and vasopressin -- takes over.
"It's more of a stress-reduction system," she said.
Rhesus macaques that inhaled oxytocin paid more attention to each other and treated each other more kindly. However, there are some people who've been together for decades but report the same romantic feelings they felt when they were newly in love. Brain scans of those couples show that same tell-tale activity in the caudate nucleus and VTA.
Charlie and Kim Thronson of Salt Lake City haven't had their caudates scanned, but say after 20 years of marriage, they still have those romantic feelings. They hold hands a lot and talk or text five to ten times a day. She often catches him staring at her with his "googly eyes."
Diamond says it's possible these couples have caudates that are more primed for activity and habituate to stimulation more slowly. Another possibility, she says, is those couples make more of an effort to do novel and challenging things together. Research shows that newness and challenge tends to excite those dopamine regions.
"Oh, we're going skydiving and I'm excited and scared at the same time and I'm doing it with you," Diamond said."Something about that experience tends to heighten those passionate feelings."
"As the years go on, I thought I'd get 'hmm, I love you, whatever,'" Kim Thronson said. "But I have found that 20 years later, I am more in love with him now than I think it was when I met him."
"It's not just that puppy love thing," Charlie Thronson added. "You start off that way. It develops into this deeper thing. I'm not sure where it shows up on the MRI, but it certainly has been there for us."
Several nights ago, Justin Hedin surprised Hayley Madsen at a restaurant with a to-go box with a diamond ring inside. Madsen squealed with surprise and delight. Hedin proposed on bended knee. Madsen said yes.
She couldn't help it. She's hooked on love.
"The more we learn about love the more we realize that we are wired to feel this way," Diamond said."We evolved to feel passionately, to want others to be near us, and I think that makes it more exciting to think that basically everything about us prepared us to feel this way."