PEA, Oxytocin, and other Chemicals of Passionate Love

From the Lecture Series: Understanding the Mysteries of Human Behavior

By Mark Leary, Ph.D., Duke University

Passionate love is not the result of a twist of fate or a spiritual incident beyond our understanding. It is, like other psychological experiences, a result of chemicals and brain activity. Hormones and neurotransmitters play a significant role. Like other psychological experiences, not knowing the processes of love can lead to hurtful results.

Love in the summer sun with bubble blower,romantic inflating colorful soap bubbles in park.
Many chemicals and hormones are involved in passionate love, and after they go back to a normal level, the passion is gone. (Image: Akuma-Photo/Shutterstock)

Passionate love has proven biochemical bases. This is the kind of love experienced with a romantic partner, one that involves sexual desire usually. There are many studies conducted on the brain when passionate love is involved. Researchers scanned people’s brains in an fMRI scanner while they looked at photographs of either strangers or people they were in love with. The results showed interesting things about brain activities in love.

This is a transcript from the video series Understanding the Mysteries of Human Behavior. Watch it now, on The Great Courses Plus.

Dopamine and Passionate Love

When the participants of the fMRI study looked at pictures of those they were in love with, the caudate nucleus was activated in the brain. This area of the brain has receptors for a neurotransmitter called dopamine. Dopamine causes feelings of exhilaration, gives people extra energy, focuses their attention, and makes them want rewards.

These are all experienced when someone is in love as well.

Learn more about what makes people happy.

Phenylethylamine or PEA

Couple in love. Focus on hands.
PEA gives couples who have recently fallen in love the excessive energy and interest that they show. (Image: Kitja Kitja/Shutterstock)

Phenylethylamine or PEA is the second neurotransmitter involved in passionate love. It is a chemical associated with amphetamines, and its effects on people’s moods and energy are similar to those of various stimulants.

This is why people in love feel energized, upbeat, and optimistic. PEA and dopamine together give enough energy and reason to a person to stay up all night and talk to the person they are in love with.

When a romantic relationship fails, the emotional crash and the occasional depression are similar to what people feel when they stop taking amphetamines or other stimulants. Although the psychological pain of losing an important relationship is a part of feeling down after a breakup, the lack of chemicals that used to be produced due to love is a major part.

Oxytocin and Love

The third chemical in both companionate and passionate love is oxytocin. Unlike PEA and dopamine, oxytocin is released in close non-romantic relationships as well. Family relationships, friendships, and other types of love involve release of oxytocin as well.

Oxytocin is the hormone responsible for the close psychological connection a person feels with their loved ones, whether it is a romantic partner or a parent. Hugging a long-term partner or a child, a mother’s nursing an infant, and orgasm, all release oxytocin. It leads to the feeling of social connection and being bonded with the other person, regardless of the type of relationship.

Lovers and parents with children show similar activities that make them feel good: long eye contact, touches, being physically close to the other person, and hugging. Even baby talk is common in many romantic relationships.

Even if oxytocin enters the body from an external source, it makes people feel closer to other people and trust them more. It makes people more empathetic and helps them understand other people better.

Obsession and Compulsion in Passionate Love

When a person is in love, they show patterns similar to those in patients of obsessive-compulsive disorder (OCD). They cannot stop thinking about the other person—uncontrollable thoughts, feelings, and ideas. As a result, they decide to do certain things (compulsion), like being with the other person.

Scientists believe that people with OCD have problems with serotonin, another important neurotransmitter that matters in the regulation of mood, sleep, learning, and other processes that involve the brain.

Learn more about how much men and women really differ.

Serotonin, Love, and OCD

In a study in Italy, three groups of people were tested for serotonin to see if those in love show similar serotonin patterns to patients with OCD: people who had fallen in love in the last six months and reported that they were obsessed about the loved one; people who had been clinically diagnosed with OCD; and people who were neither in love nor diagnosed with OCD.

The blood test results confirmed the hypothesis: those passionately in love and those with OCD showed similar serotonin patterns, i.e., 40% less than the group that was neither in love nor had OCD.

Learn more about what makes relationships succeed or fail.

Love through Time

marriage icon, people head in love, blue man and red woman heads in love, surrealistic romantic dream,together forever, couple in love sculpture with hearts inside
There are more elements than passion required for a successful relationship. (Image: Fona/Shutterstock)

The early passion in love will eventually fade away. The love, wanting, respect, and commitment can last forever, but the high passion will disappear in a long-term relationship. After 20 years of marriage, people are still in love, but not passionately anymore.

Physiologically, oxytocin takes over eventually and becomes the core of the relationship, while PEA and dopamine lower and gain a more normal level.

In terms of evolution, the excitement needs to stay around long enough for the couple to reproduce. After that, evolution no longer cares for the parents, but the children must find a partner and reproduce again. Thus, passionate love declines, especially after having children, but the relationship can survive and strive without it, too.

Common Questions about Passionate Love

Q: What is PEA?

Phenylethylamine or PEA is a neurotransmitter involved in passionate love. PEA is a chemical that is related to amphetamines and affects people’s moods and energy, like various stimulants.

Q: Is oxytocin released only in romantic relationships?

No, oxytocin is not limited to passionate love. Oxytocin is a hormone that promotes a feeling of social connection and being bonded with another person. It is released naturally when one hugs a long-term partner or their children. It is also released when a mother nurses her infant, and also during orgasm.

Q: What chemicals are involved in love?

Dopamine, oxytocin, serotonin, and Phenylethylamine or PEA are among the essential chemical components of passionate love.

Q: Does love disappear in long-term relationships?

Passionate love does not disappear after some years. Instead, it gets less exciting, and mainly hormones and chemicals related to trust and loving keep the relationship happy and healthy.

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