Neurobiological research in psychiatry has increasingly placed emphasis on understanding how neural systems go awry in psychiatric disorders. Toward this end, advanced imaging methods go beyond the study of isolated brain areas, probing the connections within neural networks. Diffusion imaging (DI) assesses white matter (WM) microstructure, informing us about the physical state of these connections (the wiring within a system). More than 50 DI studies have been published in bipolar disorder (BD) in the past decade, most commonly reporting lower fractional anisotropy (FA) in a range of different brain areas. This issue of JAMA Psychiatry contains an important contribution to the DI literature in a study with a large enough sample to address 2 important questions in DI BD research: where WM deficits are most consistent and how abnormalities vary across subtypes of BD.
Cullen KR, Lim KO. Toward Understanding the Functional Relevance of White Matter Deficits in Bipolar Disorder. JAMA Psychiatry. 2014;71(4):362-364. doi:10.1001/jamapsychiatry.2013.4638