The Love Hormone-autism Connection

Hadassah researchers investigate whether disruptions to oxytocin activity during pregnancy and birth could be one of the causes of the disorder.

Dan Even
Dan Even
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Dan Even
Dan Even

Love is a matter of hormones, as scientists proved a number of years ago, and one of the hormones that is associated most clearly with falling in love is oxytocin. Yet researchers at Jerusalem's Hadassah University Hospital in Ein Karem are focusing on the relationship between low levels of oxytocin in the human body and autism.

"Autism expresses itself in disturbances of communication, both verbal and chiefly emotional, and in repetitive movements," according to lead researcher Dr. David Mankuta, the head of labor and delivery in the hospital's obstetrics and gynecology department. The research team seeks to examine the relationship between disruptions to exposure to the hormone and the development of autism."

Previous studies have demonstrated that children with autism have lower levels of oxytocin in their blood than children without autism. One such study, carried out by the Hadassah researchers together with the Hebrew University of Jerusalem's psychology department and published in 2011, showed a decline in the immunological components that operate the oxytocin system. Some studies have found levels of oxytocin in people with autism to be half of those measured in people without autism.

Oxytocin is popularly referred to as the "love hormone." Animal studies have shown that oxytocin is released during sexual contact, and that the brains of animals that bond in pairs are rich in the hormone.

A group of researchers at Bar-Ilan University, led by Prof. Ruth Feldman of the Department of Psychology and the Brain Research Center, reported in August 2012 on similar findings in human beings. The oxytocin levels in 60 couples who became involved shortly before the study was carried out were higher than in a control group of 43 individuals who lived alone. In their article, which was published in Psychoneuroendocrinology, the researchers conclude that the hormone plays an important role in the earliest phases of a romantic relationship.

Oxytocin, however, apparently plays an equally important role in child development. The hypothesis now being tested at Hadassah holds that even though autism is generally not diagnosed before the age of two or three years, disruptions to oxytocin activity during pregnancy and birth could be one of the causes of the disorder, the origins of which are still considered an enigma. Research teams have now detected signs of autism in infants as young as one year, and some claim that preliminary signs of the disorder can be detected even earlier.

There are no tests that can check for autism in the fetus, but there are genetic, demographic and biological factors that can increase the risk for the disorder. A number of anatomical markers have been identified that are more common among children who are later diagnosed with autism, such as a high, arched palate, changes in the cerebellum and a relatively large head circumference. An additional marker was discovered recently when researchers found that in people with autism the ring finger is longer than the index finger.

The Hadassah research team published an article this year surveying the anatomical changes that can be detected in prenatal screenings. "It is important to stress, nevertheless, that there is no way at present to diagnose autism during pregnancy, but rather only during the infant's first year," Mankuta says.

Hadassah Ein Karem recently opened a new clinic for families of children with autism, whose aim is to affect the next pregnancy and reduce the likelihood of another child with autism being born into the same family. Even though there is no medical consensus about the prenatal markers for autism, this type of clinic represents a new front in the battle against this increasingly common disorder.

According to figures issued recently by the Social Affairs Ministry, the number of people who were diagnosed with an autism spectrum disorder increased fivefold between 2004 and 2011, from 1,507 in 2004 to 7,344 in 2011. The Health Ministry estimates that one out of every 150 children in Israel has autism, and some experts put the number even higher, at one out of 100. Last March the U.S. Centers for Disease Control estimated this ratio in the United States at one out of 88.

"We believe that with certain treatments the risk for developing autism can be reduced for the future siblings of a child who has already been diagnosed with autism, and yet the medical and scientific community still does not know the specific factors that cause autism," Mankuta said.

Since autism is four times more common in boys than girls, couples who want to have additional children after having a child who has been diagnosed with an autism spectrum disorder are offered the choice of using pre-implantation genetic diagnosis in order to select for a female embryo only. Women are also offered preventive treatments during the next pregnancy, including the administration of progesterone in order to reduce the risk of a preterm birth, which increases the risk of autism as well as the use of steroids to accelerate development of the unborn baby's lungs and aspirin to reduce the risk of preeclampsia, another condition that has been implicated as a risk factor for autism.

The new study being carried out by the Hadassah Ein Karem research team in partnership with Prof. Nurit Yirmiya of the Hebrew University psychology department is also examining the link between overexposure to oxytocin during birth and the development of autism.

Gynecologists are familiar with oxytocin mainly as a treatment administered in the final weeks of pregnancy and also to induce labor, since its effects include causing uterine contractions and stimulating lactations. In the West, oxytocin is given to 40 percent of new mothers at some point before, during or after giving birth. In recent years the hormone has also been credited with playing a role in the bonding process between mother and newborn infant.

Even before the findings were worked up, the hospital clinic decided to introduce preventive measures based on the assumption that a disturbance to the activity of the hormone could lead to the development of autism. "There are drugs to prevent early contractions that are given routinely in some pregnancies and that inhibit the effects of oxytocin," Mankuta explains, adding, "We will examine whether their use might be linked to the development of autism. In addition, we are examining whether the administration of oxytocin to induce labor might be harmful down the road and stimulate autism." According to one of the hypotheses that being tested, the use of oxytocin to induce labor may depress the body's natural secretion of oxytocin, thus increasing the newborn's risk of developing autism later on.

Another study, this one led by Prof. Richard Ebstein of the Hebrew University psychology department and Mankuta, found a molecule known as CD38 that is responsible for regulating the secretion of oxytocin in children. Oxytocin is created in the hypothalamus, which is located in the base of the brain, and also functions as a neurotransmitter. It was later determined that under laboratory conditions, Vitamin A increases the concentration of this molecule in children whose oxytocin levels are low and restores the hormone's secretion levels.

In parallel, the levels of certain vitamins and biological substances that have been linked to the development of autism are being tested in pregnant women. These include the thyroid hormone, Vitamin A and folic acid.

"Autism is a very enigmatic disease and there are many factors involved. Oxytocin is one of them," says Mankuta. "At this stage we are not giving oxytocin to pregnant women in order to prevent autism, but the research attempts to examine, in various ways, whether there is a way to raise its level in the fetus and cause a positive effect."

Some research groups abroad have already tried to treat autistic children with oxytocin in order to improve their social connections with their parents and their surroundings. A study carried out in Toronto that was published this month found an improvement in the social functioning and the quality of life of children with autism who were treated with a nasal spray containing oxytocin, which allowed the hormone to penetrate the brain.

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