Brain networks: foundations and futures in bipolar disorder.

BACKGROUND: Bipolar affective disorder is a common psychiatric illness with an often episodic nature, the neurobiological basis of which remains elusive. Symptom clusters in bipolar disorder can be conceptualized in terms of disordered brain networks, and doing so may aid our understanding of the varied presentations, differing illness courses and treatment responses. AIMS: To review the rationale behind proposed disordered brain network function in bipolar disorder and the evidence of network dysfunction from imaging studies together with an overview of more novel techniques pertinent to this field.
METHODS: Medline databases were searched using the terms bipolar disorder, imaging, connectivity and brain networks. Relevant articles were reviewed and bibliographic cross-referencing was used to focus on key areas of interest, supplemented by additional Medline searches as required.
RESULTS: Structural and functional imaging studies support the concept of brain network dysfunction in bipolar disorder. Novel techniques such as diffusion tensor imaging and resting state network analysis can assess such dysfunction more directly, but there are few studies specific to bipolar disorder.
CONCLUSIONS: Brain network dysfunction is a useful framework for considering the varied presentations of bipolar disorder. Advanced imaging techniques are increasingly available, with the potential to provide insights into this important area.