P 151 Amygdala gray matter volume and social relating in Schizophrenia

Abstract

Background Poor social relating is a prominent feature of schizophrenia. Patients frequently manifest deficiencies in social integration and overall social functioning, including the acquisition and maintenance of relationships. They report a reduced desire for social affiliation and higher levels of social anxiety. The amygdala has been suggested as an important node in social brain networks. In healthy individuals, it has been shown that a larger amygdala volume is associated with a more extended social network. These findings emphasize the potential involvement of the amygdala in supporting social affiliation and the engagement in social interactions. Methods By using structural magnetic resonance imaging, the present study examined for the first time the relationship between amygdalar gray matter volume and social relating in 35 schizophrenia patients (15 women) taking antipsychotic medication. Mean age of patients was 30 years (SD: 7). Mean duration of illness was 6 years (SD: 5). Social anhedonia, interaction anxiety, extraversion, and sociable tendencies were assessed as indices of social relating on the basis of rating scales and questionnaires. Patients’ diagnoses were determined by senior psychiatrists and confirmed by trained interviewers with the Structured Clinical Interview for DSM-IV, Axis I disorders. T1-weighted high-resolution structural images were acquired in a 3-Tesla scanner. The VBM8-toolbox was used for preprocessing the structural images with recommended default parameters. The preprocessed gray matter images were smoothed. Second-level analyses were performed using SPM8. Results A principal component analysis was performed on the five social relating instruments using SPSS20. Participants’ loading score on the resulting major component was entered in the subsequent MRI statistical models as an indicator of social relating. Higher scores reflect heightened social relating, characterized by less social anhedonia and asociality, less social interaction anxiety, and higher extraversion and desire to socialize. The modulated gray matter images of patients were entered into a regression model with the individual social relating component as regressor of interest. Additional regression models were calculated with age and gender as nuisance covariates. A correlation between gray matter volume in the right amygdala and enhanced social relating was revealed. Discussion Our data indicate a significant association between higher amygdalar gray matter density and enhanced social relating. Volumetric decreases in the amygdala appear to be related to higher social anhedonia, social interaction anxiety, introversion, and reduced sociability in schizophrenia. Our results are in accordance with earlier functional imaging studies in schizophrenia, which demonstrated that reduced amygdala responsiveness to social-emotional stimuli is associated with higher levels of social anhedonia and social malfunctioning. A larger amygdala volume could be interpreted as important neural prerequisite to successfully manage increased processing demands of a complex social life.