Effects of oxytocin on psychiatric symptoms depend on personality

A study of hospitalized patients with severe mental illness in Israel revealed that the effects of the hormone oxytocin on psychiatric symptoms depend on personality characteristics. Oxytocin administration improved symptoms in participants low in openness and extraversion, but led to a deterioration of the working alliance with the therapist in participants low in agreeableness and neuroticism. The study was published in Psychoneuroendocrinology.

Oxytocin is a hormone produced by the hypothalamus and released by the pituitary gland in the brain. It plays an important role in social bonding, trust, and intimacy. It is released in large amounts during hugging, cuddling, and sexual activity. For this reason, it is often referred to as the “love hormone.”

It has also been suggested that oxytocin can facilitate psychotherapeutic interventions by modulating trust and the sense of safety. However, studies conducted to explore this yielded inconclusive results. Some studies reported no facilitating effect, some reported some positive effects, and some even reported adverse effects. Researchers have thus proposed that effects of oxytocin might depend on the context and differ between individuals.

Study author Dana Tzur Bitan and her colleagues wanted to further explore factors on which the effects of oxytocin depend. They hypothesized that the effects of oxytocin might depend on attachment patterns and personality traits of an individual. They conducted a study on a group of patients suffering from severe mental illness.

Participants were 87 patients of the Shalvata Mental Health Center in Israel. 55% of the patients suffered from affective disorders, 17% from anxiety disorders, and the remaining participants had a variety of other mental illnesses. 23 participants dropped out of the study before it was finished. Participants were randomly divided into two groups.

Participants in one of the groups received oxytocin twice a day – at 8:00 and 17:00 every day for 4 weeks. Participants in the other group received an identically looking placebo (substance with no physiological effect) at the same time for the same time period. This was administered by the nursing staff who was not informed about which participant belonged to which group. Both oxytocin and placebo were administered in the nose using a spray. During this period, study participant attended psychodynamic psychotherapy sessions two or three times a week.

Participants completed assessments of emotional attachment (the Experiences in Close Relationships Scale), personality (the Big Five Inventory), depression (the Hamilton Rating Scale for Depression), and anxiety (the State-Trait Anxiety Inventory) at the start of the study and after the study was completed, four weeks later.

The working alliance between the psychotherapist and the patient was evaluated after each psychotherapy session. The level of distress was also evaluated after each psychotherapy session. Prolonged distress was evaluated once every week. Additionally, participants completed an assessment of suicidal ideation (the Scale for Suicidal Ideation).

Results showed that the effects of oxytocin do not depend on attachment patterns, but that they do depend on personality. Neither avoidant or anxious attachment patterns moderated the effects of oxytocin on the working alliance with the psychotherapist. However, personality was a different story.

These researchers found that oxytocin given to introverts led to a slight decrease in suicidal ideation (frequency and intensity of ideas about committing suicide). However, in extraverts, people with pronounced extraversion, oxytocin administration led to a slight increase in suicidal ideation. In participants low in openness to experience, oxytocin led to a decrease in depression symptoms, but this did not happen in participants very open to experience.

In extraverts, but not in introverts, oxytocin reduced the working alliance with the psychotherapist. In participants with low levels of neuroticism, oxytocin reduced the working alliance. This effect was absent in participants high in neuroticism. A similar effect was found in participants low on agreeableness.

“The results indicated that personality traits modulated the effect of oxytocin administration. Specifically, when extraversion and openness to experience were low, oxytocin administration was associated with improvement in suicidal ideation and depression, respectively. Low extraversion was also associated with higher symptomatic improvement following oxytocin administration across several anxiety and depression scales as compared to high extraversion,” the study authors concluded.

The study sheds light on the effect of oxytocin on important psychological processes. However, it also has limitations that need to be taken into account. Notably, the sample consisted of participants with different diagnoses. It is possible that effects might differ on people with specific mental conditions. Participants in the study were also receiving relatively large doses of psychiatric medications and interactions between these and oxytocin cannot be ruled out.

The study, “A double-edged hormone: The moderating role of personality and attachment on oxytocin’s treatment facilitation effect”, was authored by Dana Tzur Bitan, Ariella Grossman-Giron, Omer Sedoff, Sigal Zilcha-Mano, Uri Nitzan, and Hagai Maoz.