Brain structural correlates of subclinical body dysmorphic symptoms : a gender-informed approach

Background: Despite the prevalence and impact of body dysmorphic concerns on psychosocial functioning, there remains a scarcity of research examining the neurobiological and psychological correlates of these symptoms in healthy individuals. Given that previous studies on clinical body dysmorphic disorder (BDD) revealed brain structural and functional differences in limbic, frontal, and visual processing areas, as well as cognitive and emotional deficits, we sought to investigate the associations between grey matter volume (GMV), subclinical body dysmorphic symptom severity, alexithymia, and rumination. Methods: We assessed GMV using structural magnetic resonance imaging (MRI) in a sample of healthy participants. We employed a region-of-interest (ROI) approach, including the medial orbital superior frontal gyrus (SFG), precuneus, amygdala, hippocampus, anterior cingulate cortex (ACC), and inferior occipital gyrus (IOG). We analyzed associations between ROIs and body dysmorphic symptoms, with particular emphasis on the impact of gender on these associations. We corrected p values using threshold-free cluster enhancement and established a conservative family-wise error (FWE) threshold value of 0.05. Results: We included 219 participants. Our analysis revealed an interaction effect between body dysmorphic symptom score and gender in the right amygdala (pFWE = 0.01), bilateral hippocampus (right pFWE = 0.02; left pFWE = 0.04), and right IOG (pFWE = 0.01), reflecting a trend toward positive associations between body dysmorphic symptoms and GMV among men and negative associations among women. No significant relationships were found in the SFG, ACC, and precuneus. Women exhibited elevated levels of body dysmorphic symptoms compared with men, and body areas of concern differed between genders. Additionally, alexithymia predicted body dysmorphic symptom severity among women only. Limitations: The specificities of structural MRI measurements and cross-sectional study designs should be taken into account when interpreting these results. Conclusion: Our findings suggest an association between subclinical body dysmorphic symptoms and brain structure in limbic and visual areas moderated by gender. Insights into body dysmorphic symptomatology drawn from subclinical samples may offer valuable insights into predisposing factors in the etiology of BDD and may aid in developing targeted prevention strategies.