Healthy adults with higher levels of subclinical body dysmorphic symptoms showed gender-specific differences in gray matter volume in brain regions involved in visual and emotional processing, according to a cross-sectional neuroimaging study published in Journal of Psychiatry & Neuroscience.
The study included 219 psychiatrically healthy adults—95 men and 124 women—from the Münster Neuroimaging Cohort. Participants underwent structural magnetic resonance imaging and completed self-report measures assessing body dysmorphic symptoms, alexithymia, and rumination. Structured clinical interviews excluded participants with any lifetime psychiatric disorder, including body dysmorphic disorder (BDD).
Researchers used a predefined region-of-interest analysis to evaluate gray matter volume in the superior frontal gyrus, precuneus, amygdala, hippocampus, anterior cingulate cortex, and inferior occipital gyrus (IOG). Analyses adjusted for age and total intracranial volume, and results were corrected for multiple testing.
The most robustly supported findings involved the right IOG, a visual processing region that contains the occipital face area and is involved in early face perception. Researchers identified a statistically significant interaction between body dysmorphic symptom severity and gender in the right IOG, with higher symptom severity associated with greater gray matter volume among men and lower gray matter volume among women.
The study also identified statistically significant interaction effects in the right amygdala and bilateral hippocampus. However, subgroup-level analyses in those limbic regions did not remain statistically significant after correction for multiple testing, although the directional pattern was similar to that observed in the IOG.
The researchers noted that abnormalities in visual processing have been consistently implicated in BDD, including a tendency toward detail-focused rather than holistic visual processing. They suggested the IOG findings may reflect gender-specific neurobiological pathways involved in the perception and interpretation of facial features.
Associations in the amygdala and hippocampus may support prior evidence implicating limbic structures in emotional and social information processing in BDD. However, the researchers emphasized that structural magnetic resonance imaging cannot determine functional activity, and volumetric differences could represent either predisposing factors or consequences of altered neural activity.
Women reported higher body dysmorphic symptom scores overall, whereas men reported higher alexithymia scores, particularly on measures assessing difficulty describing feelings. No gender differences were observed in difficulty identifying feelings.
Among women, higher alexithymia scores and greater difficulty identifying feelings were associated with greater body dysmorphic symptom severity. The difficulty identifying feelings subscale showed the strongest association. No statistically significant associations between alexithymia and body dysmorphic symptoms were observed among men following correction for multiple testing.
Rumination was not associated with body dysmorphic symptom severity in either group following correction for multiple testing. The researchers suggested this may indicate that rumination becomes more clinically relevant at the threshold of diagnosable BDD rather than during subclinical symptom expression.
Researchers also observed gender-related differences in appearance concerns. Men more commonly reported concerns related to muscularity and hair, whereas women more frequently reported facial concerns involving hair, ears, nose, eyes, skin, and mouth.
No statistically significant associations were identified in the superior frontal gyrus, anterior cingulate cortex, or precuneus, and exploratory whole-brain analyses did not reveal additional structural correlates.
The researchers described the overall effect sizes as moderate, suggesting the observed associations were meaningful but not large.
The researchers cautioned that the cross-sectional design precluded causal inference and limited conclusions regarding whether structural brain differences predispose individuals to body dysmorphic symptoms or develop as a consequence of them. They also noted that findings from healthy adults with subclinical symptoms may not generalize to patients with diagnosed BDD. Additional limitations included reliance on self-reported symptoms, imbalance in the number of male and female participants, and lack of gender diversity beyond participants identifying as men or women.
“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,” wrote lead study author Antonia Küttner, MSc, of the University of Halle, Germany, and colleagues.
Disclosures: The researchers reported no competing interests. Funding was provided by the German Research Foundation, the German Center for Mental Health, the University of Münster Faculty of Medicine, graduate funding from the state of Saxony-Anhalt, and the Open Access Publication Fund of Martin Luther University Halle-Wittenberg.