New study maps brain networks behind narcissism using advanced machine learning

A recent study provides insight into how structural brain networks contribute to narcissistic personality traits. By using advanced machine learning techniques, researchers identified specific patterns in gray and white matter that predict narcissistic tendencies. The findings were recently published in the European Journal of Neuroscience.

Individuals with high levels of narcissism often exhibit a grandiose sense of self-importance, a need for excessive admiration, and a lack of empathy for others. These traits can significantly impact mental health and interpersonal relationships, leading to various social and personal difficulties. Narcissistic Personality Disorder, the more extreme manifestation, affects about 1% to 15% of the U.S. population in clinical settings and presents a unique challenge in mental health care due to its complex and overlapping symptoms with other personality disorders.

Despite the prevalence of narcissistic traits and NPD, research into their neurological underpinnings remains limited. Existing studies primarily focus on either gray or white matter separately and often use univariate methods that do not account for the complex interactions within the brain. This study aimed to fill this gap by examining the joint contributions of both gray and white matter to narcissistic traits using multivariate machine learning approaches.

“In the Clinical and Affective Neuroscience Lab, we are interested in creating neuro-predictive models of personality to serve as future guidance for clinical classification and prevention of the development of a full disease. Personality is the heart of who we are. However, our understanding of the neural bases of personality and how personality can be predicted from neural features is something far to be understood. In our lab we are trying to pave the way to reach this aim,” said study author Alessandro Grecucci, a professor of affective neuroscience and neurotechnology at the University of Trento.

To investigate the neural underpinnings of narcissistic personality traits, the researchers utilized data from the MPI-Leipzig Mind Brain-Body dataset, which includes MRI and behavioral data from 318 participants. For their analysis, they focused on a subset of 135 healthy individuals, comprising 64 females and 71 males with a mean age of 31.94 years. These participants were selected based on their good health, absence of medication use, and no history of substance abuse or neurological diseases.

Personality traits were assessed using the Personality Styles and Disorders Inventory (PSDI), a validated self-report inventory that measures various personality styles and can indicate potential personality disorders. The researchers focused on the narcissistic, histrionic, insecure/avoidant, and paranoid subscales to differentiate the neural networks associated with these traits.

To analyze the data, the team used Parallel Independent Component Analysis (p-ICA), a machine learning technique that identifies independent components in multimodal data. This method allowed them to examine the co-variation of gray and white matter. They then applied stepwise regression and Random Forest regression to predict narcissistic traits based on these brain networks.

The researchers identified eight independent networks in both gray and white matter. Gray matter consists mainly of neuronal cell bodies, dendrites, and synapses, and it is involved in processing and interpreting information in the brain. White matter, on the other hand, is composed of bundles of myelinated axons that connect different gray matter areas, facilitating communication between them.

Among these networks, one in particular stood out for its strong association with narcissistic traits. This network encompassed regions in the frontal, temporal, and parietal lobes, including areas involved in social cognition and empathy, such as the superior temporal gyrus, angular gyrus, and middle temporal gyrus. Additionally, it included white matter regions in the cerebellum and thalamus, which are critical for cognitive and emotional processing.

Notably, the gray matter regions identified largely overlapped with the Default Mode Network (DMN). The DMN is known for its role in self-referential thinking, social cognition, and the processing of emotional experiences. This overlap suggests that the DMN plays a crucial role in the manifestation of narcissistic traits, reinforcing the idea that these traits are deeply rooted in the brain’s structure and function related to self-perception and social interactions.

The study’s predictive model, developed using Random Forest regression, confirmed the robustness of these findings. This model demonstrated that the identified network could reliably predict narcissistic traits in new individuals, highlighting the potential for using brain imaging data to assess personality traits.

“We are trying to develop neural models of narcissistic personality,” Grecucci told PsyPost. “Narcissistic Personality Disorder is a mental health condition characterized by a pervasive pattern of grandiosity, a constant need for admiration, and a lack of empathy for others. This disorder can lead to significant impairments in personal and professional relationships and overall functioning. In a previous study, we focused on the grey matter side of it. In this new paper, we extended our findings to include the white matter contribution.”

“Thanks to an innovative data fusion machine learning method, we found a covarying grey and white matter circuit that encodes enough information to predict narcissistic personality. A predictive model was then extracted thanks to which the level of your narcissism can be predicted from this circuit.”

“This circuit overlaps with the Default Mode Network, a network of interacting brain regions that is active when a person is at rest and related to mind-wandering, introspection, thinking,” Grecucci explained. “We are making a point that this could be one of the hubs that encodes our personality. We demonstrated its involvement also in other personality traits such as borderline, antisocial, and more recently on obsessive-compulsive personality.”

The research sheds light on the neural underpinnings of narcissistic personality traits. But there are limitations to consider. The reliance on structural data alone means that functional brain data were not considered, which could provide a more comprehensive understanding of the neural mechanisms.

The sample size, while larger than in many previous studies, could still be increased for more robust brain-wide association analyses. Another limitation is the assessment of narcissistic traits using the PSDI, which does not distinguish between vulnerable and grandiose subtypes of narcissism. Future research could explore these subtypes separately to see if different brain networks are involved.

The study, “Narcissus reflected: Grey and white matter features joint contribution to the default mode network in predicting narcissistic personality traits,” was authored by Khanitin Jornkokgoud, Teresa Baggio, Richard Bakiaj, Peera Wongupparaj, Remo Job, and Alessandro Grecucci.