Love is the most exalted and sublime of human emotions. It has inspired breathtaking works of art, journeys through continents and even the tragedies of war. Given its powerful hold on humanity it’s surprising that it’s been traditionally neglected by the brain sciences. In spite of this, a new dawn in romance research has begun to bud in recent years, and love has finally blossomed in the lab.

While romantic love has always been an obsession of the psychoanalysts, they were often creating little more than a new poetry of emotion, often beautiful, often bizarre, but rarely explaining more than their own metaphors.

Always a little late to the game, it wasn’t until the end of the 1990s that neuroscience fell head over heals for love. The first to become inspired by this new passion was, as if we needed to ask, an Italian.

Psychiatrist Donatella Marazziti and her colleagues measured levels of a protein that transports the neurotransmitter serotonin in the blood of 20 people who had recently fallen madly in love, 20 people with obsessive compulsive disorder (OCD) and 20 healthy comparison participants.

People with OCD experience intrusive, obsessive thoughts and are often described as having an ‘over-valued idea’ – an almost semi-delusional state where a particular thought becomes the focus of attention.

Marazziti, already an established OCD researcher, knew that serotonin had previously been linked both to obsessional thoughts and to sexual attraction, and wondered whether something similar might be going on in the early stages of romance.

She found that the group of patients with OCD and the recently love-struck were no different in terms of the serotonin transporter protein, suggesting the brain began to function markedly differently as love blossomed.

Although measuring the blood is a fairly crude way of looking at how the brain works, the researchers were struck by the similarities between these two states:

This aspect we believe underlies the obsessive pre-occupation so characteristic of the early stage of love (which, in rare instances, might persist for a lifetime of abstract idealization that leads to poetry and music dedicated to the love object). As far as we are aware, this is the first report of changes in the 5-HT [serotonin] transporter during a physiological state; it would suggest that being in love literally induces a state which is not normal – as indeed suggested by a variety of colloquial expressions used throughout the ages in different countries, all of which refer generally to falling ‘insanely’ in love or to being ‘lovesick’

Since this initial flirtation, love has become a hot topic in the neurosciences, with whole conferences dedicated to it and numerous scientific studies being published every year.

Perhaps unsurprisingly, the traditional connection between love and madness has not been dispelled by these recent studies.

In fact, a 2007 study that looked at new love in adolescents found so many striking similarities between the intensity of teenage romance and hypomania, a symptom of manic-depression, that the authors warned researchers to look out for the love-struck when conducting research with young people, so as not to bias their results.

Link to abstract of study of the serotonin transporter and romantic love.

Link to abstract of study on hypomania and adolescent love.