Increased temporo-insular engagement in unmedicated bipolar II disorder: an exploratory resting state study using independent component analysis.
OBJECTIVE
Despite numerous structural and functional magnetic resonance imaging studies, the neurobiology of bipolar disorder (BD) is still incompletely understood. Resting-state functional magnetic resonance imaging (rsFMRI) allows for the study of intrinsic functional connections between brain areas, which may reflect the pathophysiology of BD. Most previous rsFMRI studies conducted in BD have included a majority of medicated patients, making simple interpretation with respect to pathophysiology difficult.


METHODS
Participants were 15 antipsychotic agent- and mood-stabilizer-naïve young adults with bipolar II disorder (BD-II), and 20 healthy controls group-matched for gender, age, and cognitive ability. Independent component analysis (ICA) was used to identify eight commonly studied resting-state networks (RSNs). Between-group comparisons were conducted using dual regression and corrected for family-wise error (FWE) across space and the number of components (pFWE < 0.05).


RESULTS
In comparison to controls, participants with BD-II had increased coherence across several brain regions, including the bilateral insula and putamen, across a temporo-insular network. No between-group differences in engagement of the default mode network were found.


CONCLUSIONS
This was the first ICA-based rsFMRI study conducted among unmedicated individuals with BD. Given the young age (mean = 23 years) and antipsychotic agent- and mood-stabilizer-naïve status of our participants with BD-II, temporo-insular functional connectivity is a candidate vulnerability marker for BD. Further work is needed to relate resting-state differences to detailed understanding of pathophysiology.
Department of Psychiatry, University of Oxford, Oxford, UK.
Sarah W
SW
Yip
Clare E
CE
Mackay
Guy M
GM
Goodwin
D000328:Adult; D001714:Bipolar Disorder / Q000473:pathology*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D010100:Oxygen / Q000097:blood; D025341:Principal Component Analysis; D012146:Rest; D013702:Temporal Lobe / Q000098:blood supply / Q000503:physiopathology*; D055815:Young Adult
D010100:Oxygen
bipolar II disorder; default mode; dual regression; independent component analysis; medication; resting state