Sex differences in the functional and structural neuroanatomy of dental phobia

Although dental phobia is a common mental disorder, which afflicts both men and women, little is known about sex differences at the neural level. Patients suffering from dental phobia (20 men, 25 women) and healthy controls (18 men, 23 women) participated in a functional magnetic resonance imaging (fMRI) experiment. They were shown pictures depicting dental treatment, generally fear-eliciting, disgust-eliciting and neutral contents. After the fMRI experiment, the participants rated the affective value of the pictures. Additionally, grey matter volume (GMV) was compared between patients and controls, as well as between the sexes. Male and female patients responded differently to the phobogenic pictures. Women showed greater activation of the caudate nucleus, whereas men exhibited enhanced dorsolateral prefrontal cortex (DLPFC) involvement. Their DLPFC activation was negatively correlated with experienced arousal. Dentophobic females were characterized by a greater caudate volume relative to phobic males. The GMV of this structure was positively correlated with experienced arousal during exposure and symptom severity, only in female patients. This study provides first evidence of sex-specific brain activation and structure in patients suffering from dental phobia. The neural pattern during symptom provocation as well as the brain structural specificity might mirror different attention and self-control strategies of both sexes. The consideration of such differences could contribute to greater effectiveness in treating dental phobia.