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"Trust" hormone oxytocin found at heart of rare genetic disorder

Kirsten Gilham, a young woman with Williams syndrome, undergoes an ERP (event related potential) test. The test measures the electrical activity of the brain.

Kirsten Gilham, a young woman with Williams syndrome, undergoes an ERP (event related potential) test. The test measures the electrical activity of the brain.

The hormone oxytocin—often referred to as the "trust" hormone or "love" hormone for its role in stimulating emotional responses— plays an important role in Williams syndrome (WS), according to a study published in PLoS ONE.

The study, a collaboration between scientists at Salk and the University of Utah, found that people with WS were flushed with the hormones oxytocin and arginine vasopressin (AVP) when exposed to emotional triggers.

"Williams syndrome results from a very clear genetic deletion, allowing us to explore the genetic and neuronal basis of social behavior," says Ursula Bellugi, director of Salk's Laboratory for Cognitive Neuroscience and a co-author on the paper. "This study provides us with crucial information about genes and brain regions involved in the control of oxytocin and vasopressin, hormones that may play important roles in other disorders."

WS arises from a faulty recombination event during the development of sperm or egg cells. As a result, virtually everyone with WS has exactly the same set of genes missing (25 to 28 genes are missing from one of two copies of chromosome 7). There also are rare cases of individuals who retain one or more genes that most people with the disorder have lost.

To children with WS, people are much more comprehensible than inanimate objects. Despite myriad health problems, they are extremely gregarious, irresistibly drawn to strangers and insistent upon making eye contact. They have an affinity for music. But they also experience heightened anxiety, severe spatial-visual problems and have an average IQ of 60, as well as suffer from cardiovascular and other health issues. Despite their desire to befriend people, they have difficulty creating and maintaining social relationships.

The results of the new study indicate that the missing genes affect the release of oxytocin and AVP through the hypothalamus and the pituitary gland. About the size of a pearl, the hypothalamus is located just above the brain stem and produces hormones that control body temperature, mood, sex drive, sleep, hunger and thirst, and the release of hormones from many glands, including the pituitary. The pituitary gland, about the size of a pea, controls many other glands responsible for hormone secretion.

The researchers' findings may help in understanding human emotional and behavioral systems and lead to new treatments for devastating illnesses such as WS, post-traumatic stress disorder, anxiety and possibly even autism.