Inhibitory brainstem reflexes under external emotional-stimuli in schizoid and histrionic personality disorders

Abstract Background Schizoid personality disorder patients behave inhibitedly and histrionic personality disorder patients openly, which might be due to different cortical and brainstem inhibitory activities. The exteroceptive suppressions of the temporalis muscle activity, especially the second period (ES2), under different external-emotions might be different in the two personality disorders. Methods We have invited 18 patients with schizoid, 17 with histrionic personality disorders, and 37 sex- and gender-matched healthy volunteers, to undergo the ES2 test under external emotions of Blank (nil emotion), Disgust, Erotica, Fear, Happiness, and Sadness. Their ongoing affective states of mania, hypomania and depression were also measured. Results One-way ANOVA has detected that schizoid group scored higher on depression than healthy volunteers did, histrionic group scored higher on mania and hypomania than healthy volunteers did. Compared to those in controls, ES2 durations under fear and sadness in schizoid and under erotica in histrionic were longer. Conclusions Our results indicated that the brainstem inhibitory dysfunction was more pronounced under fear and sadness in schizoid, but more pronounced under erotica in histrionic patients, which might imply different emotional control therapies for the two personality disorders.