The latest findings hint at why autistic children are more interested in objects and ideas than they are in other people.
And that insight could lead to new treatments. The study, which was published in the journal Nature, shows for the first time, in mice, a connection between the “bonding” hormone oxytocin and the brain systems that produce pleasure and motivation. Oxytocin levels surge during orgasm, pregnancy and in the first stages of new romance, which is why it’s known as the “love” or “cuddle” chemical; but some scientists have shown genetic changes in autistic children that may alter these effects.
Now, researchers at Stanford University have detailed how interfering with oxytocin’s activity can inhibit social behavior. Oxytocin partners with another brain chemical, serotonin, which is responsible for feelings of satisfaction and reward, in order to make social contact comforting, and worth repeating. And that rewarding reinforcement may not be occurring properly in the brains of autistic individuals.
“People with autism-spectrum disorders may not experience the normal reward the rest of us all get from being with our friends,” the study’s lead author, Dr. Robert Malenka, professor of psychiatry and behavioral sciences at Stanford University said in a statement, “For them, social interactions can be downright painful.”
Indeed, mice that could not activate both oxytocin and the brain chemical serotonin did not act like their normally social selves.
“It’s great study and has some interesting implications,” says Dr. Eric Hollander, director of the Autism and Obsessive-Compulsive Spectrum Disorders clinic at Montefiore/Albert Einstein College of Medicine, who was not involved in the research.
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While oxytocin has long been suspected to play a role in the altered social development typical of autism, until now, scientists were unable to connect oxytocin to the pleasure regions of the brain in social animals, like mice, that aren’t monogamous. (In monogamous prairie voles, oxytocin activation was linked to reward and believed to solidify the bond between mates, but it wasn’t clear if the same held true for animals with non-monogamous relationships.) If oxytocin receptors weren’t present in reward regions, for example, it wouldn’t make sense that animals would enjoy the social contact the hormone promoted or seek it out.
The connection to serotonin may also explain why antidepressants like Prozac, known as selective serotonin reuptake inhibitors (SSRI) can sometimes be helpful in autism, allowing patients to connect better with others rather than withdrawing and being isolated. The results also provide hope that adding oxytocin to SSRI or serotonin-based treatments might lead to more improvements in behavior.
“Our results suggest that maybe combining oxytocin with a serotonin drug might be beneficial,” says Malenka. Clinical trials testing oxytocin as a treatment for autism are ongoing; one trial, which only lasted four days, failed to find an effect, but researchers believe that longer exposure is probably necessary.
Hollander already uses a combination of Prozac or similar drugs with oxytocin in his clinical practice. “I have seen synergistic effects and I think they go very well together,” he says, noting that they tend to work on different symptoms, “I use SSRI’s to target higher order [compulsive and repetitive] rituals, routines and anxiety and use oxytocin to help with social communication and reward.”
If autism results in part from children failing to take pleasure in social contact that others find fun, then it may also explain why early behavioral interventions that make social contact more inviting and enjoyable seem to help. Some studies have shown that starting these therapies early enough can even change brain activity to resemble more normal patterns that find social interactions rewarding and satisfying.
While there is already a drug that can improve sociability—MDMA (otherwise known as ecstasy or Molly)— it’s probably too controversial to consider even for autistic adults, let alone children. It acts by influencing both serotonin and oxytocin, but can cause potentially fatal overheating if taken in the wrong setting. Researchers are testing the drug as a treatment for post-traumatic stress disorder, but it’s not clear yet if similar tests are justified in autism cases.
Scientists, however, are hoping that further study on the drug can yield better understanding of how either modified versions of MDMA, or drugs like it, might help in treating conditions like autism. “There are risks and you can get some toxicity,” Hollander says, “But I do think the phenomenon of MDMA playing a role in [making social experiences more compelling] and shifting attention from self to others and communion is very interesting.”