Distinguishing bipolar disorder and borderline personality disorder: an exploration of clinical and neuroscience informed approaches

Thesis

Bipolar disorder and borderline personality disorder are common psychiatric diagnoses. One is a mood disorder with a strong genetic basis while the other is a disorder of personality commonly related to abusive experiences in childhood. Despite contrasting aetiologies they can be difficult to differentiate because of overlapping clinical presentations and symptoms. Diagnostic accuracy is important because of their polarised treatment approaches: long term treatment with mood stabilizers for bipolar disorder and psychotherapy for borderline personality disorder.

A qualitative study of psychiatrists revealed comprehensive knowledge of the diagnostic criteria however, many expressed the view that diagnostic criteria did not assist diagnostic differentiation. These findings were validated in a large electronic survey of UK psychiatrists. A detailed study of actual diagnostic processes revealed that this scepticism appeared to influence actual practice. Clinicians largely ignored diagnostic criteria but continued to give diagnoses.

Age and IQ matched women with bipolar disorder, borderline personality disorder and a healthy control group were compared in a series of cognitive tasks. Borderline personality disorder was associated with a failure to establish and maintain reciprocal cooperation in a game theoretic measure of social exchange. This behavioural change was not seen in euthymic bipolar disorder. Borderline personality disorder was also associated with an insensitivity to reward and losses in a risky decision-making task. Using a simple two-choice reaction task post error slowing was significantly amplified in the borderline group despite overall reaction times and error rates being similar in all three groups.

Clinical diagnostic practice as revealed in this study is not adequate to reliably differentiate between bipolar disorder and borderline personality disorder. Laboratory measures of social exchange, decision making and post-error slowing highlight fundamental difficulties in borderline personality disorder not seen in euthymic bipolar disorder. These findings support the differentiation of bipolar disorder from borderline personality disorder and offer translational models for developing and evaluating new treatments for borderline personality disorder.

Authors: Saunders, K

• Publication date: 2014
• DOI: 10.5287/ora-7jd1qbdp8
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: Oxford University, UK
• Language: English
• Keywords: bipolar disorder; borderline personality disorder
• Subjects: Psychiatry; Cognitive Neuroscience; Bipolar disorder; Neuroscience