A small new study led by researchers from the Stanford School of Medicine suggests low levels of a hormone called vasopressin, measured in three-month-old babies, may serve as a predictive biomarker of autism spectrum disorder (ASD) in later childhood.

“Autism currently is diagnosed behaviorally, mainly in children ages two to four years old, but these new findings suggest we might be able to better predict which newborns will go on to develop the disorder as children,” explains John Constantino, co-senior author on the project from Washington University School of Medicine in St. Louis.

Researchers have slowly been homing in on the role of vasopressin in ASD for several years. Prior studies have found children and teenagers with ASD have lower levels of vasopressin in cerebrospinal fluid samples compared to those without the disorder. A small pilot study last year revealed daily treatment with a vasopressin nasal spray improved the social abilities of children with ASD.

This new research set out to investigate whether low levels of vasopressin in cerebrospinal fluid (CSF) could serve as a predictive biomarker, predating the onset of ASD symptoms in childhood. To do this, the researchers studied a rare archive of CSF samples taken from babies three months old and younger.

In general practice, when babies develop serious fevers in the first few months of life, CSF samples are taken to make sure brain infections are not the source of the fever. Many of these CSF samples are subsequently stored for future research, and the new study homed in on nine samples from babies who went on to be diagnosed with ASD.

The researchers compared CSF vasopressin levels from the babies who went on to be diagnosed with ASD to a control group of CSF samples from infants that had not shown symptoms of ASD by the age of 12. The findings confirmed the researchers’ hypothesis, with significantly lower CSF vasopressin levels found in the ASD cases compared to the control.

Interestingly, two of the nine ASD cases did not show significantly low levels of vasopressin. Those two cases were found to also present with later diagnoses of attention deficit hyperactivity disorder (ADHD).

Another compelling secondary finding was the lack of any difference in CSF oxytocin levels between ASD and control samples. Oxytocin is hormone some research has suggested plays a role in ASD.

Karen Parker, co-senior author on the new study from Stanford University, says larger studies are underway to see if these results can be replicated in bigger cohorts.

“This new biological clue from a rare and unprecedented collection of newborn human spinal fluid samples needs to be pursued in larger numbers of children,” says Parker. “Given the alignment of these findings with studies in older children and in nonhuman primates, we want to understand why this neuropeptide might have such a marked, predictive association with the development of autism spectrum disorder because it appears to be extremely predictive of future risk.”

The researchers also plan to investigate blood-based biomarkers that may correlate with vasopressin and/or ASD. Obviously, broad testing of newborn babies' CSF through spinal tap is not a feasible way of detecting those most at risk of ASD. So, this novel CSF-vasopressin connection may be useful for directing future research, but it most likely won’t become a diagnostic test in its current form.

The new study was published in the journal PNAS.

Sources: Stanford Medicine, Washington University School of Medicine in St. Louis