Oxytocin Deficiency – Biomarker – Anxiety in Children
A study by Karen Parker and her research team from the Stanford University School of Medicine links low levels of oxytocin with anxiety in children.
Oxytocin is a hormone that’s produced in the hypothalamus and released into the bloodstream by the pituitary gland. Its main function is to facilitate childbirth, which is one of the reasons it is called the “love drug” or “love hormone.”
The uterine-contracting properties of the principle that would later be named oxytocin were discovered by British pharmacologist Henry Hallett Dale in 1906, and its milk ejection property was described by Ott and Scott in 1910.
Animal studies highlight the importance of oxytocin in parturition, milk letdown, protective aggression, social behaviors and pair bonding between mothers and infants and in mating pairs.
Human studies have confirmed oxytocin’s role as a social hormone, mediating many social behaviors involved in forming attachments. This hormone is increasingly recognized as an important regulator of human social behaviors, including social decision making, evaluating and responding to social stimuli, mediating social interactions, and forming social memories.
In addition, oxytocin is intricately involved in a broad array of neuropsychiatric functions, and may be a common factor important in multiple psychiatric disorders such as autism, schizophrenia, mood and anxiety disorders.
Recent evidence indicates that oxytocin is an anxiolytic hormone, as it decreases the release of stress hormones, while oxytocin imbalances have been associated with both anxiety (HJ Lee et al., Prog Neurobiol, 2009, 88:127) and depression.
In healthy controls (HC), oxytocin decreases cortisol release and anxiety in response to social stress, reduces amygdala activity to fearful or threatening visual images or emotional faces, increases trust behavior in a money-transferring game, increases the ability to interpret mental states, and increases the amount of time spent gazing at the eyes when viewing faces.
To conduct research on the connection between oxytocin and emotion, scientists want to assess the hormone’s levels in the brain. But sampling cerebrospinal fluid, the liquid bathing the brain, requires an invasive technique called a lumbar puncture. Measuring blood oxytocin is much easier, but some researchers have questioned whether blood oxytocin levels truly reflect what’s happening in the brain.
A new Stanford study simplifies the problem: It is the first research in children, and some of the first in any age group of humans, to indicate that blood and CSF oxytocin levels track together
The Stanford study, published in the journal Molecular Psychiatry demonstrates that both plasma and cerebrospinal fluid (CSF) oxytocin concentrations significantly and negatively predict trait anxiety in children. The study also provides perhaps the first evidence in children that plasma oxytocin concentrations are a valid surrogate for CSF oxytocin concentrations.
These observations substantiate recent studies demonstrating an anxiolytic effect of intranasal oxytocin administration, which is combined with a reduction of stress-induced cortisol concentrations in both healthy subjects and individuals with anxiety symptoms.
According to the authors patient stratification as per plasma oxytocin levels may improve the assessment of the therapeutic potential, and the prediction of patients most likely to benefit from oxytocin treatment. The authors also suggest that patients with lower plasma oxytocin concentrations and higher levels of anxiety will benefit most from therapy with oxytocin.
These preliminary findings also suggest that impaired OXT signaling may be a biomarker of anxiety in humans, and a potential target for therapeutic development in individuals with anxiety disorders.
In conclusion, evidence from animal and human studies substantiates the hypothesis of an imbalance of the endogenous brain OXT system in the etiology of anxiety disorders, particularly those with a social component such as social anxiety disorder. In addition, such an imbalance of the OXT system is also likely to be the consequence of chronic OXT treatment resulting in a dose-dependent reduction in OXT receptor availability and increased anxiety.
Cover Image Credit (Left Panel): Parvocellular neurons (yellow) secrete oxytocin and vasopressin (red) to numerous brain regions, including the amygdala, brainstem, and anterior pituitary. Magnocellular neurons (green) in the hypothalamic nuclei secrete oxytocin and vasopressin into the peripheral circulation via the posterior pituitary (axonic secretion). Additionally, they secrete these peptides into the extracellular fluid the hypothalamus (dendritic secretion). From: Oxytocin and vasopressin: linking pituitary neuropeptides and their receptors to social neurocircuits, by Danielle A. Baribeau and Evdokia Anagnostou, Front. Neurosci., 24 September 2015.; Right panel: Drs. KJ Parker and DS Carson.