People caught up in the intense passion of blooming love often report feeling swept away or feeling a kind of natural high. Such reactions might have a basis, at least in part, in brain chemistry, according to researchers Michael Liebowitz, author of The Chemistry of Love (1983), and Anthony Walsh, author of The Science of Love (1991). These investigators contend that the initial elation and the energizing "high" of excitement, giddiness, and euphoria characteristic of passionate love result from surging levels of three key brain chemicals: norepinephrine, dopamine, and especially phenyl — ethylamine (PEA). These chemicals, called neurotransmitters, allow brain cells to communicate with each other, and they are chemically similar to amphetamine drugs; thus they produce amphetamine-like effects, such as euphoria, giddiness, and elation.
The amphetamine-like highs and elevated sexual arousal associated with new love typically do not last—perhaps in part because the body eventually develops a tolerance to PEA and related neurotransmitters, just as it does to amphetamines. With time, our brains simply become unable to keep up with the demand for more and more PEA to produce love’s special kick. Thus the highs that we feel at the beginning of a relationship eventually diminish. This observation provides a plausible biological explanation for why passionate or romantic love is short-lived.
Liebowitz points out another parallel to amphetamine use. He notes that the anxiety, despair, and pain that follow the loss—or even potential loss—of a romantic love relationship are similar to what a person addicted to amphetamines experiences during drug withdrawal. In both cases the loss of mood-lifting chemicals results in a sometimes protracted period of emotional pain.
Other brain chemicals exist that help to explain why some relationships endure beyond the initial highs of passionate love. The continued progression from infatuation to the deep attachment characteristic of long-term loving relationships results, at least in part, from the brain gradually stepping up production of another set of neurotransmitters called endorphins. These morphinelike, pain-blunting chemicals are soothing substances that help produce a sense of euphoria, security, tranquility, and peace. Thus they can cause us to feel good when we are with a loved partner. This could be another reason why abandoned lovers feel so terrible after their loss: They are deprived of their daily dose of feel-good chemicals. Perhaps in the near future medical intervention may be able to boost the level of these chemicals to counter a dangerous depression sometimes associated with the "heartbreak" of lost love (Fischetti, 2011a).
As we learned in Chapter 6, dopamine and oxytocin are brain chemicals that also contribute to sexual arousal and feelings of being in love. Results of a study provide evidence of the role of dopamine in the chemistry of love. In this investigation, researchers used functional magnetic resonance imaging (fMRI) to scan the brains of men and women while they viewed photos of a loved romantic partner and of a close friend. It was the photos of lovers, not friends, that caused areas of the brain rich in dopamine to "light up" (Bartels & Zeki, 2004). Other research utilizing fMRI has provided additional evidence of a strong link between feelings of being in love and the release of neurotransmitters and other brain chemicals such as dopamine, serotonin, oxytocin, and vasopression (Fischetti, 2011b).
Recent research suggests that the use of hormonal contraceptives may reduce women’s attractiveness to potential love/sex partners, a condition that may be based on altered chemistry (Wang, 2011). Women appear to emit chemical signals when they are fertile and/or ovulating, and these chemical cues appear to be altered or eliminated
by hormonal-based birth control methods. Thus, it appears that birth control pills or injections may mask the chemistry of attraction that plays a role in bringing romantic partners together (Wang, 2011). This possibility opens up an area for new research, which may or may not confirm that hormonal birth control methods are linked to the chemistry of attraction and love.
Just as we know little about why people fall in love, we have no simple explanation for why they fall in love with one person instead of another. A number of factors are often important: proximity, similarity, reciprocity, and physical attractiveness.