Differentiating between bipolar and unipolar depression in functional and structural MRI studies

Kyu Man Han, Domenico De Berardis, Michele Fornaro, Yong Ku Kim

    Research output: Contribution to journalReview articlepeer-review

    142 Citations (Scopus)


    Distinguishing depression in bipolar disorder (BD) from unipolar depression (UD) solely based on clinical clues is difficult, which has led to the exploration of promising neural markers in neuroimaging measures for discriminating between BD depression and UD. In this article, we review structural and functional magnetic resonance imaging (MRI) studies that directly compare UD and BD depression based on neuroimaging modalities including functional MRI studies on regional brain activation or functional connectivity, structural MRI on gray or white matter morphology, and pattern classification analyses using a machine learning approach. Numerous studies have reported distinct functional and structural alterations in emotion- or reward-processing neural circuits between BD depression and UD. Different activation patterns in neural networks including the amygdala, anterior cingulate cortex (ACC), prefrontal cortex (PFC), and striatum during emotion-, reward-, or cognition-related tasks have been reported between BD and UD. A stronger functional connectivity pattern in BD was pronounced in default mode and in frontoparietal networks and brain regions including the PFC, ACC, parietal and temporal regions, and thalamus compared to UD. Gray matter volume differences in the ACC, hippocampus, amygdala, and dorsolateral prefrontal cortex (DLPFC) have been reported between BD and UD, along with a thinner DLPFC in BD compared to UD. BD showed reduced integrity in the anterior part of the corpus callosum and posterior cingulum compared to UD. Several studies performed pattern classification analysis using structural and functional MRI data to distinguish between UD and BD depression using a supervised machine learning approach, which yielded a moderate level of accuracy in classification.

    Original languageEnglish
    Pages (from-to)20-27
    Number of pages8
    JournalProgress in Neuro-Psychopharmacology and Biological Psychiatry
    Publication statusPublished - 2019 Apr 20

    Bibliographical note

    Publisher Copyright:
    © 2018 Elsevier Inc.


    • bipolar depression
    • bipolar disorder
    • functional imaging
    • magnetic resonance imaging
    • major depressive disorder
    • mood disorder
    • structural imaging
    • unipolar depression

    ASJC Scopus subject areas

    • Pharmacology
    • Biological Psychiatry


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