Love and biology are deeply entwined. Love can make a heart race
and a lack of chemistry can turn romance into friendship. But just
what is the nature of this link? Can biochemistry cause
Dr. Hagop Akiskal won the Ig-Nobel prize in Chemistry for trying
to answer this very question. The Ig-Nobel prizes are organized by
the Annals of Improbable Research and distributed by Nobel Prize
winners. They are designed to celebrate research that “makes people
laugh and then makes them think." Akiskal’s work on how love looks
a lot like obsessive-compulsive disorder does just that.
Akiskal is the director of the International Mood Center at the
University of California, San Diego. Much of his career has been
devoted to understanding and redefining illnesses such as
depression and bipolar disorder. These topics may seem a long way
off from love, but after meeting Akiskal it is easy to imagine why
he was drawn to researching romance. Part scientist, part poet,
Akiskal has always been fascinated by love and determined to
understand the things that fascinate him.
Born in Armenia just one generation after the Armenian Holocaust
of the early 1900s, Akiskal’s natural curiosity and interests drove
him toward literature and other intellectual fields that were
considered controversial at the time. His family pushed for him to
go into a career that would be less dangerous. “They were more for
me to do something solid like become a doctor or an engineer,
fields where there was no controversy. Intellectuals are dangerous,
they go to dangerous places or say dangerous things and I was known
for that,” says Akiskal.
Akiskal landed in medical school but this did nothing to deter
him from saying controversial things. Disillusioned by the way
psychiatry was approached in the 1960s and worried by the chasm
that existed between biology and psychiatry, Akiskal developed a
radical theory stating that behavior, emotion, neurochemistry and
neurophysiology were all related. Akiskal submitted his
“Integrative Theory” to Science. “I had the daring idea of sending
it to Science. I thought it was important enough. Science, even in
those days, was the standard. It was mainly astrophysics and
biology. I think there had only been one psychiatrist published in
Science before. They liked it and there it is; it’s history. At the
age of 26, I became very famous.” This notoriety led to his
appointment as Senior Science Advisor to the Director of the
National Institute of Mental Health.
It was during this time that Akiskal met Dr. Donatella
Marazziti, an Italian scientist who had become interested in
obsession and how much it resembled another human condition: love.
The similarities between the early stages of love and obsession are
easy to see. People are often preoccupied with the object of their
affection and unable to focus on daily activities. Marazziti’s
group had recently implicated a particular seratonin transporter in
obsessive-compulsive disorder. With Akiskal’s help they wanted to
see if this transporter might also play a role in the preoccupation
that can accompany love.
To do this they talked to participants who claimed to be in
love. Importantly, these participants were preoccupied with their
love object for four hours or more every day. People preoccupied by
an object of obsession for four or more hours a day are considered
to have moderately severe obsessive-compulsive disorder.
Levels of the 5-HT seratonin transporter were found to be significantly decreased in participants in love and participants suffering from obsessive-compulsive disorder when compared to a normal “control” group (Marazitti et al, 1999). This evidence supported the theory that obsessive-compulsive disorder and love have a lot in common biochemically. It also implicated serotonin as the chemical behind romantic love.
One of the hallmarks of romantic love is that it is fleeting.
Even when couples stay together they generally settle into a more
comfortable stage in which preoccupation decreases and they are
able to function more normally outside of the relationship.
“Romantic love is something that starts at one point and ends at
one point. Mercifully it ends because it’s such an intense emotion
that it must end at some point,” says Akiskal. What does this mean
for the biology? In the follow up to this study Akiskal and
Marazitti found that when these participants were re-tested 12-18
months later their 5-HT levels had returned to normal. The
participants reported that they no longer felt distracted and
preoccupied with the object of their affection. If serotonin is the
biochemistry of love, and if it fades, how does anyone stay
Research from the prairie vole, a mammal that mates for life,
suggests this may be the work of yet another chemical: vasopressin.
After sex male prairie voles express high levels of vasopressin.
They become devoted to their partner and protect her from the
attention of other males, but if vasopressin expression is blocked
the male prairie vole fails to become devoted after mating and
leaves the female vulnerable to the attention of other males.
Vasopressin isn’t just released after sex. It’s elevated in both
the male and female during pregnancy and has been shown to increase
in males just from holding a baby. Human males with a particular
variant of the vasopressin receptor have been shown to be less
likely to get married and more likely to have spouses who are
unsatisfied with the marriage when they do. Vasopressin may have
evolved as a way to bind couples together to care for young.
Serotonin may be the chemical behind love, but vasopressin seems to
be the chemical of monogamy (Young, 2009).
In the last decade a multitude of hormones have been implicated
in regulating the type and intensity of love that a person
experiences. Dopamine and endorphins play their own role in
romantic love, and oxytocin and testosterone can affect long-term
love. These biochemicals not only interact with the cells of the
brain; they interact with one another. In addition to this
complicated biochemistry there is another factor, which Akiskal is
the first to point out: “Romantic love is much more than a
serotonin receptor. It’s immensely more; it’s somewhere between the
atoms of the cells, the subatomic particles, all the way beyond
poetry and music and joy and intense happiness which is
Marazitti D, Akiskal HS, Rossi A, Cassano GB. Alteration of the
platelet serotonin transporter in romantic love. Psychol. Med. 1999
Young LJ. Being human: love: neuroscience reveals all. Nature. 2009 Jan 8, 457(7226):14
Author: Jennifer Rust for MySDscience
March 24, 2009