ORIGINAL RESEARCH article
Front. Psychiatry
Sec. Mood Disorders
Volume 16 - 2025 | doi: 10.3389/fpsyt.2025.1610703
This article is part of the Research TopicExploring Neuromodulation and Neuroimaging Techniques for Psychiatric Disorders: Insights from Preclinical and Clinical StudiesView all 4 articles
Prefrontal activation in bipolar and unipolar depression patients in the letter fluency tasks and category fluency tasks: A functional near-infrared spectroscopy study
Provisionally accepted
Juan Hui1
Haiyue Dai1
Lu Qi2
Juan Wang1
Guimei Cui1Junlin Mu1
Lin Zhao3Shina Gu2
Juan Li1*
Zhao-Hui Zhang2*- 1Henan Provincial Mental Hospital, Xinxiang, China
- 2The First Affiliated Hospital of Xinxiang Medical University, Xinxiang, Henan Province, China
- 3Shandong Mental Health Center, Jinan, Shandong Province, China
Select one of your emails
You have multiple emails registered with Frontiers:
Notify me on publication
Please enter your email address:
If you already have an account, please login
You don't have a Frontiers account ? You can register here
Background: Distinguishing bipolar disorder (BD) from unipolar depression (UD) remains a critical clinical challenge. Improved diagnostic accuracy could enhance therapeutic outcomes for both conditions. This study aims to (1) identify functional near-infrared spectroscopy (fNIRS)-based biomarkers differentiating BD from UD, and (2) compare frontotemporal hemodynamic responses during phonological (LFT) and semantic (CFT) verbal fluency tasks. Methods: We recruited 100 participants: 33 with UD, 34 with BD, and 33 healthy controls (HC). Cortical oxygenation changes ([oxy-Hb]) were recorded using 52-channel fNIRS during LFT and CFT performance. Findings: The [oxy-Hb] activation in the UD and BD groups was lower compared to the HC group. Most channels demonstrated the [oxy-Hb] activation is lowest in BD patients, followed by UD patients, and the highest in the HC participants. Compared to CFT, UD and HC patients exhibited more extensive prefrontal cortex activation during LFT. This study found differences in [oxy-Hb] activation in the ventrolateral prefrontal cortex (VLPFC) between BD and UD patients during the CFT period. Conclusion: Our findings indicate that the LFT elicits more extensive prefrontal activation, with differential engagement of the VLPFC in BD compared to UD. These results suggest potential neuroimaging biomarkers for distinguishing between UD and BD, while also providing insights into the neural substrates of language processing.
Keywords: letter fluency tasks, category fluency tasks, fNIRS, Unipolar depression, Bipolar depression
Received: 12 Apr 2025; Accepted: 08 Sep 2025.
Copyright: © 2025 Hui, Dai, Qi, Wang, Cui, Mu, Zhao, Gu, Li and Zhang. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence:
Juan Li, Henan Provincial Mental Hospital, Xinxiang, China
Zhao-Hui Zhang, The First Affiliated Hospital of Xinxiang Medical University, Xinxiang, 453100, Henan Province, China
Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.