Biochemistry has always been a subject of interest to me; and since I saw this fascinating article discussing love and the brain’s biochemistry, some time ago, I figured it may be of interest to readers here.

Luckily I saved a copy, because the original article seems to have since disappeared from its original website. Therefore, I’ll repost my copy here, and people interested in Biochemistry may learn some things to their advantage.

My Love is Chemical by James Adams

(www.brain.com)

Valentine’s Day is here, Spring is approaching, and as the poet Tennyson wrote, “a young man’s fancy lightly turns to thoughts of love,” and he might have added, neurotransmitters and hormones. Researchers have begun to unlock the secrets behind the age-old mystery of love, and they’re finding that, for both men and women, the key really is in the chemistry.

“There’s no doubt in my mind that there are a whole series of biochemical pathways that are triggered when two people meet and are attracted to each other,” says James Weinrich, Adjunct Professor of Psychiatry at the University of California, San Diego. “One of those pathways would have to do with the experience of being ‘head-over-heels’ preoccupied with someone. Where you can’t get that person out of your head, they intrude into your thoughts, and everything that they do is remarkably charming to you.”

As anyone who has ever experienced it knows, the rush of falling “head-over-heels” in love is intoxicating. And it appears to be due, in part, to the effects of a neurotransmitter released by a region of the brain called the hypothalamus. That neurotransmitter, called “the molecule of love” by Theresa Crenshaw, M.D., author of The Alchemy of Love and Lust, is phenyl ethylamine (PEA).

“It causes that euphoria of falling in love. It gives that wonderful feeling, that feeling that this person that you’re attracted to can do no harm, this person has nothing wrong with them. When PEA is high is when ‘love is blind,” explains Robert Friar of Ferris State University in Michigan. It’s kind of a chemical Cupid, firing an arrow into the brain and firing up those feelings of falling in love.

However, PEA doesn’t act alone. When you meet someone that you’re attracted to, PEA works in conjunction with a whole slew of neurotransmitters floating around in that love-addled brain of yours, including dopamine, nor-epinephrine and serotonin. Dopamine may be involved in the “attention-getting” phase of attraction, signalling the brain that a potential reward, in this case a love interest, is nearby and helping focus your attention on that person. Nor-epinephrine gets your blood racing and primes you for action (or to flee, in some cases–it’s involved in the so-called “fight or flight” response), while serotonin is closely associated with the control of moods, which everyone knows can fluctuate drastically in the process of falling in love.

“It’s very complex,” says Friar. “When you’re discussing the neurotransmitters, it’s like listening to an orchestra,” he explains. “Unless all the instruments play together in the proper rhythm and the proper sequence, you won’t get the proper effect.” All the neurotransmitters are working together to create a complex behaviour that can be compared to a symphony.

In this case, a symphony of attraction and love, and that symphony can come to a final note. As most people have, at one time or another, experienced the thrill of falling in love, so have they experienced the fading of that initial excitement, a levelling off of the intense feelings of attraction, and possibly, a falling out of love.

What brings about the change from those original feelings? It seems that the effects of PEA have a time limit. “Typically PEA is released for three to five years,” says Friar, and he’s being optimistic. Other researchers put the end of PEA’s influence at 18 months to three years.

That may be the reason so many relationships tend to end in that time period. Once the initial thrill wears off, couples may drift apart. But obviously many stay together beyond this point in time. Some evidence suggests the reason is that a second biochemical pathway kicks in and helps the couple develop a longer-lasting relationship. This second pathway is involved in bonding and forming long term attachments and may be under the influence of at least two hormones, oxytocin and vasopressin.

The Hormones of Love
Testosterone is known to be important in regulating sexual desire in both men and women. It’s the hormone that helps create the desire to get out there and get that exciting neurotransmitter symphony going, but “there’s been a big bias in favour of the so-called sex hormones, like testosterone and oestrogen, to try to explain just about everything having to do with human sexuality,” says James Weinrich.

There appear to be other hormones involved in sexual behaviour, specifically in creating the next (perhaps slower) movement of the symphony, when committed couples “settle down” for a life together. One of the hormones, oxytocin, has been long known to be involved in childbirth and breast feeding in women.

Recent research in animals has shown that oxytocin plays a role in the bonding of mating pairs of prairie voles, a type of monogamous rodent. If a female prairie vole is given oxytocin and shown a male prairie vole, she will then pick out and bond with that specific male when later placed in cage containing many males.

Early studies in humans have suggested that women that produce higher levels of oxytocin during pleasant experiences, like massage or remembering a positive relationship, tended to have higher “well-being” in relationships.

Both men and women release oxytocin at the moment of sexual orgasm, suggesting that it might be involved in strengthening the bond between couples.

Another hormone, vasopressin, which is also known as anti-diuretic hormone, or ADH, and plays and important role in kidney function, has been shown to have an effect on male prairie voles similar to the effect oxytocin had on females.

“It’s not surprising to discover that there’s more than a sex steroid pathway that’s going on to influence the things that we humans associate with sexuality, namely bonding and love,” says Weinrich.

In Conclusion
As Robert Friar points out, there’s still much to be learned about the neurochemical basis of love and attraction. Much of the research has been conducted in animals, and it’s impossible to do the same experiments with human subjects, so results have to be extrapolated. And animal experiments are limited in the sense that, while you can measure levels of neurotransmitters and hormones, you can’t, in Friar’s words, “ask a rat how it feels.”

Some die-hard romantics might be appalled at the idea that love can be explained in terms of biochemistry, but an underlying chemical explanation doesn’t make the feeling of love any less real or intense. If one still needs some amount of mystery in relation to love, perhaps it lies in the question of how a complex system of chemical reactions can lead to the feelings and behaviours we associated with any type of emotion, including love. As James Weinrich says, “Give Mother Nature credit for being able to put together some pretty sophisticated and complicated mechanisms.” Mechanisms that scientists will be unravelling for many years to come.

Sources:

Crenshaw, Theresa L. The Alchemy of Love and Lust: How Our Sex Hormones Influence Our Relationships. Pocket Books; 1997.

Insel TR, Winslow JT, Wang Z, Young LJ. Oxytocin, vasopressin, and the neuroendocrine basis of pair bond formation. Advances in Experimental Medicine and Biology 1998;449:215-24.

Turner RA, Altemus M, Enos T, Cooper B, McGuinness T. Preliminary research on plasma oxytocin in normal cycling women: investigating emotion and interpersonal distress. Psychiatry 1999;62(2):97-113.

You might also enjoy reading:-

• Does sex on the first date increase the probability of starting a relationship?
• Coming soon: Anti-love potion No. 9
• Love hormone increases attraction
• What’s Wrong With Romance?
• Mate Love

Posted by Jonathan in Art & Literature, Biochemistry

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