Line bisection performance in patients with personality disorders.

Introduction. Normal line bisection deviation to the left of the true centre has been interpreted as resulting from relative right hemisphere activation. Right hemisphere involvement has also been associated with the problems in dependency and attachment from infancy to adulthood. This hemispheric association predicts that patients diagnosed with dependent personality disorder will deviate significantly to the left on the line bisection task. Methods. This hypothesis was tested by comparing the results of the line bisection task obtained respectively from 30 right-handed healthy volunteers and 14, 16, 18, and 26 outpatients with schizotypal, antisocial, borderline, and dependent personality disorders. Subjects completed eight horizontal line bisection tasks and the Dimensional Assessment of Personality Pathology-Basic Questionnaire (DAPP-BQ), a self-report measure of 18 traits delineating personality disorder. Results. Patients with dependent personality disorder bisected significantly leftward compared to healthy controls. Dependent personality disorder patients scored significantly higher on DAPP-BQ Insecure Attachment, and lower on DAPP Stimulus Seeking, Callousness, Intimacy Problems, and Conduct Problems compared to the healthy controls and all other patient groups. Conclusions. Line bisection differentiates dependent personality disorder from other personality disorder diagnoses and healthy controls. This study thus suggests that line bisection can be used to enhance diagnostic specificity of dependent personality disorder and localises the brain areas implicated in the disorder.