Even the toughest of hearts might melt at the sound of Elvis Presley crooning his classic song, “Love Me Tender.” Now a new study shows that when people with the genetic disorder Williams syndrome listen to that song or others, they experience changes in levels of the hormones associated with feelings of love.

The findings provide clues about the genes that are tied to people's emotions, the researchers say.

Researchers observed 21 people while they listened to music, and took blood samples to track levels of the hormones oxytocin and arginine vasopressin (AVP). The 13 participants with Williams syndrome  — a genetic disorder that can bring developmental delays and mild mental retardation, along with an overly friendly and trusting personality — experienced a spike in both hormones when music played.

Individuals without the condition saw little change to their oxytocin and AVP levels while listening. 

One woman with Williams syndrome experienced significantly higher spikes in the hormones, compared with everyone else in the study; in the experiment, she listened to the Elvis tune.

The results could help researchers treat people who have this disorder and others that share some features with Williams syndrome, such as post-traumatic stress disorder and autism, said study researcher Julie Korenberg, of the University of Utah. The research provides insight to the relationship between genes and emotions, and links AVP levels to music for the first time, she said.

People with Williams syndrome  have several genes missing from their seventh chromosome. They tend to be very friendly and have an affinity for music, but also are likely to have IQs as low as 60 and experience several health concerns, such as narrow blood vessels and high levels of calcium.

People with the condition often lack the ability to read social cues, despite their desire for friendship. Their disposition may be the result of high levels of oxytocin and AVP, according to the researchers.

At the start of the experiment, before any music was played, blood samples showed that people with Williams syndrome had three times the amount of oxytocin  as people in the control group.

Results from the hormone tests showed that the people with Williams syndrome experienced marked increases in hormone levels while listening to music.

The research "points to surprising, entirely unsuspected deleted genes involved in regulation of these hormones and human sociability,” Korenberg said. "It also suggests that the simple characterization of oxytocin  as ‘the love hormone’ may be an overreach. The data paint a far more complicated picture."

Understanding the relationship between genes, hormones and emotions will be key in treating Williams syndrome, but may also have implications for treating disorders such as autism  and anxiety, the researchers said.

The study was published June 12 in the journal PLoS One.

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