Association of grey matter cerebral blood flow with white matter integrity in relation to youth bipolar disorder.

BACKGROUND

Both cerebral blood flow (CBF) and fractional anisotropy (FA) are altered in bipolar disorder (BD). We sought to investigate the unexplored CBF-FA association in relation to youth BD.

METHODS

We recruited youth with BD, high-risk youth with a family history of BD, and healthy controls. Using 3 T magnetic resonance imaging, we measured global and regional grey matter CBF using arterial spin labelling and we measured regional FA using diffusion tensor imaging. We explored the CBF-FA association across groups, between groups, and by sex. Analyses of the BD group further examined mood effects. We conducted region-of-interest analyses of global CBF and FA, anterior cingulate cortex (ACC) CBF, and cingulate FA.

RESULTS

We included 59 youth with BD, 19 high-risk youth with a family history of BD, and 47 healthy controls. There were no significant CBF-FA associations in the overall sample. Within the BD group, higher ACC CBF was associated with higher cingulum FA (β-weight 0.30, p = 0.03), with larger effect sizes among females and asymptomatic participants. Among controls, higher global CBF was associated with lower global FA (β-weight -0.40, p = 0.05). Within-sex analyses in the overall sample revealed a small effect size association between ACC CBF and cingulum FA among females only.

LIMITATIONS: Our small sample size limited power, and our cross-sectional observational design precluded directional inferences about CBF-FA associations.

CONCLUSION

We found preliminary evidence that ACC CBF was positively associated with cingulum FA among youth with BD, which may be driven by asymptomatic female participants. These associations may relate to differences in cerebral metabolism or white matter perfusion. Prospective and experimental studies are warranted to better understand CBF-FA associations in BD.