The Association of Bipolar Spectrum Disorders and Borderline Personality Disorder

Bipolar Disorder (BD) and Borderline Personality Disorder (BPD) are two different entities sharing a variety of common features
in a number of fields and, thus, presenting difficulties in their differential diagnosis. The aim of the review is to identify
similarities and differences between BD and BPD concerning the symptomatology, causes, course and treatment of the two disorders.
A systematic electronic search of Pubmed (Medline) was conducted in order to identify all relevant scientific articles published
between 1990 and 2010. The main common clinical features of BD and BPD are affective instability and impulsivity, which, however,
present with quality differences in each disorder. In the field of neuroanatomy, BD and BPD demonstrate similarities such
as alterations in the limbic system, as well as specific differences, such as the increase in size of the amygdala in BD and
the decrease in BPD. Both disorders appear to have a significant percentage of heritability, but environmental factors seem
to hold an important role in BPD, in particular. Both BD and BPD are affected by alterations in the dopaminergic and serotonergic
system. Fuctionability and prognosis are slightly worse for BPD. Concerning medication treatment, antidepressants are considered
effective in BPD, whereas mood stabilizers are the main treatment of choice in BD. The effectiveness of a variety of psychotherapeutic
methods is still under research for both disorders. Despite the similarities and differences already being traced in clinical
and biological fields, the relationship of the two disorders has not yet been thoroughly defined.