AUTHOR=Zhou Jun , Ma Xiaoqian , Li Chunwang , Liao Aijun , Yang Zihao , Ren Honghong , Tang Jinsong , Li Jinguang , Li Zongchang , He Ying , Chen Xiaogang 

TITLE=Frequency-Specific Changes in the Fractional Amplitude of the Low-Frequency Fluctuations in the Default Mode Network in Medication-Free Patients With Bipolar II Depression: A Longitudinal Functional MRI Study

JOURNAL=Frontiers in Psychiatry

VOLUME=Volume 11 - 2020

YEAR=2021

URL=https://www.frontiersin.org/journals/psychiatry/articles/10.3389/fpsyt.2020.574819

DOI=10.3389/fpsyt.2020.574819

ISSN=1664-0640

ABSTRACT=Objective: To examine the treatment-related changes of the fractional amplitude of low-frequency fluctuations (fALFF) in the default mode network (DMN) across different bands after the medication-free patients with bipolar II depression received a 16-week treatment of escitalopram and lithium. 
 
Methods: A total of 23 medication-free patients with bipolar II depression and 29 healthy controls (HCs) were recruited. We evaluated the fALFF values of slow 4 (0. 027–0.073 Hz) band and slow 5 (0. 01–0.027 Hz) band of the patients and compared the results with that of the 29 HCs at baseline. After 16-week treatment of escitalopram with lithium, the slow 4 and slow 5 fALFF values of the patients were assessed and compared with the baselines of patients and HCs. The depressive symptoms of bipolar II depression in patients were assessed with a 17-item Hamilton Depression Rating Scale (HDRS) before and after treatment.

Results: Treatment-related effects showed increased slow 5 fALFF in cluster D (bilateral medial superior frontal gyrus, bilateral superior frontal gyrus, Right middle frontal gyrus ,and bilateral anterior cingulate), cluster E (bilateral precuneus/posterior cingulate, Left cuneus), and cluster F (left angular, left middle temporal gyrus, left superior temporal gyrus, and left supramarginal gyrus) in comparison with the baseline of the patients. Moreover, a positive association was found between increase in slow 5 fALFF values (follow-up value minus the baseline values) in cluster D and decrease in HDRS scores (baseline HDRS scores minus follow-up HDRS scores) at follow-up, the same association between increase in slow 5 fALFF values and decrease in HDRS scores was found in cluster E .


Conclusions: The study reveals the hypoactivity of slow 5 fALFF in the DMN are related to depression symptoms and might be corrected by the administration of escitalopram with lithium, implying that slow 5 fALFF of the DMN plays a key role in bipolar depression.