Lower levels of oxytocin receptors are associated with more frequent errors in overmentalization — a tendency to erroneously attribute complex mental states to others — among patients with borderline personality disorder, according to new research published in the journal Acta Psychiatrica Scandinavica. This discovery sheds new light on the relationship between the oxytocin system and the cognitive processes underpinning social interaction in borderline personality disorder.
Borderline personality disorder is a condition marked by intense emotional turbulence and impulsive actions. Patients often struggle with a profound fear of abandonment and find it challenging to maintain stable and satisfying relationships. With its myriad of symptoms stemming from a variety of biological changes, the disorder’s complexity makes it difficult to pinpoint effective treatments. Hence, the quest to identify biological markers that could lead to personalized therapy has become increasingly important.
Oxytocin, a small peptide produced in the brain, is recognized for its roles in childbirth and lactation but also has a significant impact on social behavior and emotional responses. By binding to its receptors, which are spread throughout the brain and peripheral tissues, oxytocin influences a range of social and psychological processes. Given its potential link to key symptoms like emotional instability and hypersensitivity to rejection, researchers sought to explore oxytocin’s role in the context of borderline personality.
“Borderline personality disorder is a serious mental disorder that entails significant levels of suffering and loss of quality of life for those who suffer from it, as well as important demands on the national health system,” said study author Alejandra Gálvez-Merlín, a researcher and lecturer at the Complutense University of Madrid.
“For this reason, progress in a better approach to this pathology is a priority health challenge. Recent studies suggest social cognition impairment in this group of patients, which leads us to look for biological markers that can provide more evidence of these impairments and increase the knowledge of the phenotypic and endophenotypic characteristics of people with borderline personality, with the aim of developing more specific and personalized treatment approaches.”
The study included 33 adult patients who had been formally diagnosed with borderline personality disorder according to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-V) criteria. These individuals exhibited a moderate-to-severe degree of disorder severity and a moderate level of dysfunctionality. The recruitment took place at the Personality Disorders Unit of the Hospital Clínico San Carlos in Madrid, Spain.
To assess the participants’ social cognition, specifically their Theory of Mind abilities, the researchers employed the Movie for the Assessment of Social Cognition (MASC). The MASC is designed to mimic real-life social interactions, offering a dynamic and ecologically valid assessment of how individuals perceive and interpret social information.
The assessment presents participants with social scenarios through a movie format and then assesses their ability to correctly infer the mental states of the characters involved. This process allows for the identification of overmentalization (excessive attribution of mental states), undermentalization (insufficient attribution of mental states), and absence of mentalization (physical causality attributed to social situations) errors.
Concurrent with the Theory of Mind assessment, blood samples were collected from each participant to measure plasma oxytocin levels and protein expression of oxytocin receptors.
The researchers found a significant inverse relationship between oxytocin receptor levels and overmentalization errors. In other words, patients with lower levels of oxytocin receptor levels tended to make more overmentalization errors.
“Social cognition impairments in people with borderline personality disorder seem to be related to alterations in the oxytocin system,” Gálvez-Merlín told PsyPost. “Oxytocin is a neurohormone that modulates social behaviors and parental relationships, while social cognition refers to the mental processes that enable individuals to perceive, interpret, manage and respond appropriately to social information from others.”
“Social cognition is closely related to perspective taking (i.e. understanding the situation from the other’s point of view), emotion recognition and empathy. The results of this study support the evidence for a biological substrate in these interpersonal disturbances that may lay the groundwork for future treatments to ameliorate aggressive behavior and excessive sensitivity to interpersonal rejection in these patients.”
Surprisingly, the researchers did not find a significant association between plasma oxytocin levels and the types of Theory of Mind responses in the MASC task. This indicates that while oxytocin receptor levels are linked to the propensity for overmentalization, the concentration of oxytocin itself in the plasma does not directly correlate with the types of errors made in social cognition tasks.
“Low levels of oxytocin receptors have been linked to early attachment experiences, suggesting the importance of oxytocin receptors in mediating the impact of parental care on the onset of psychopathology,” Gálvez-Merlín noted.
But the study, like all research, includes some caveats.
“The results of our study cannot affirm that oxytocin is the biological cause of the social cognition impairments in people with borderline personality disorder, Gálvez-Merlín said. “It is currently unknown whether this deficit in the oxytocin system could promote a biological vulnerability that contributes to an emotional hypersensitivity to certain stressful childhood situations, leading to the development of a disorganized attachment style, or whether the continued experience of stressful and traumatic situations produces, in the long term, a dysfunction of the oxytocin system.”
The study, “Decreased oxytocin levels related to social cognition impairment in borderline personality disorder,” was authored by Alejandra Galvez-Merlin, José M. López-Villatoro, Pilar de la Higuera-González, Alejandro de la Torre-Luque, Karina McDowell, Marina Díaz-Marsá, Juan C. Leza, and José L. Carrasco.
