Many wonder why someone involved in an illicit affair would risk everything like his or her marriage, family and career just for what may seem like a silly crush. However, scientists may have figured out the mystery of falling head over heels and why love can make even the most levelheaded of people giddy, foolish and ridiculous.

Using brain scans, investigators have been able to map out the chemical changes that occur and reveal regions of the brain that activate and regions that shut down during the blossoming days of romance.

Researchers hope that they may one day reveal why people in love sometimes go crazy and step over the mark when dealing with their lovers.

Brain scans show that a region of the brain that is essential to judgment, the brain's frontal cortex, shuts down when people fall in love. Researchers using MRI scans found that the frontal cortex deactivates when someone is shown a picture of the person they love, leading them to suspend all criticism and doubt.

"When you look at someone you are passionate about, some areas of the brain become active," Semir Zeki, professor of neuro-aesthetics at University College London said, according to the Daily Mail. "But a large part is de-activated, the part that plays a role in judgment."

Zeki says that the brain may act in this way for "higher biological purposes" to make reproduction more likely. He says that if rational judgment is suspended, even the most unlikely pair can get together and reproduce.

However, researchers note that someone in love is still capable of making other major decisions like choosing a new mortgage or negotiating a business deal. Researchers said that this sanity or ability to make rational decisions in other parts of their lives will make it harder for friends to convince them that they "they have taken leave of their senses" when it comes to a reckless affair.

Brain scans also revealed that the part of the brain responsible for fear and another region involved in negative emotions shut down, which could explain why people are so happy and unafraid that anything could go wrong when they are head over heels in love.

Past studies have revealed that levels of dopamine, a chemical in the brain that plays an important role in pleasure and pain, and is linked to desire, addiction and euphoria, are higher in people who are in love. 

Researchers said that the spike in the levels of the reward neurotransmitter dopamine might make it hard for love to give up. Previous research found that taking opioid drugs like cocaine have a comparable effect on dopamine levels as love.

When dopamine levels rise, levels of serotonin, an important hormone that governs moods and appetite, drops, making people in love feel anxious and jittery.

Another chemical that shoots up when a person is in love is the fight-or-flight adrenaline hormone that produces physical responses like racing heartbeats, sweaty palms and dry mouth. Researchers found that adrenaline spikes when people see the person they like, leading researchers suggest that the hormone may explain forbidden love or explain why two people who are only vaguely attracted to one another fall madly in love if experience an exciting or terrifying experience together.