The uncinate fasciculus in individuals with and at risk for bipolar disorder: A meta-analysis

• Published in: Journal of affective disorders 2022-01, Vol.297, p.208-216
• Main Authors: Xu, Ellie, Nguyen, Lynn, Hu, Rebecca, Stavish, Caitlin M., Leibenluft, Ellen, Linke, Julia O.
• Format: Article
• Language: English
• Subjects: Anisotropy; At-risk relatives; Bipolar disorder; Bipolar Disorder - diagnostic imaging; Diffusion Tensor Imaging; Endophenotype; Humans; Nerve Net; Uncinate Fasciculus; White matter; White Matter - diagnostic imaging
• ISSN: 0165-0327; 1573-2517
• DOI: 10.1016/j.jad.2021.10.045

•Uses region-of-interest approach to examine properties of uncinate fasciculus.•Patients with bipolar disorder show lower uncinate fasciculus fractional anisotropy.•First-degree relatives do not show lower uncinate fasciculus fractional anisotropy.•Remains inconclusive whether aberrancies in uncinate fasciculus are an endophenotype. Bipolar disorder (BD) is a severe mental disorder, characterized by prominent mood swings and emotion regulation (ER) deficits. The uncinate fasciculus (UF), a white matter tract connecting the amygdala and the ventral prefrontal cortex, has been implicated in ER. Aberrancies in UF microstructure may be an endophenotype associated with increased risk for BD. However, studies in individuals with BD and their first-degree relatives (REL) have yielded inconsistent findings. This meta-analysis takes a region-of-interest approach to consolidate the available evidence and elucidate the role of the UF in the risk-architecture of BD. Using web-based search engines, we identified diffusion tensor imaging (DTI) studies focusing on the left and right UF and conducted meta-analyses comparing fractional anisotropy (FA) and radial diffusivity (RD) between BD or REL and healthy control participants (HC). We included 32 studies (nBD=1186, nREL=289, nHC=2315). Compared to HC, individuals with BD showed lower FA in the right (WMD=-0.31, p