Differences in verbal and spatial working memory in patients with bipolar II and unipolar depression: an MSI study

Zhinan Li,Yufang Guan,Yanyan Shan,Yigang Feng,Junhao Chen,Zhongpeng Dai,Yanbin Jia,Shuming Zhong,Qing Lu,Shui Tian

doi:10.1186/s12888-021-03595-3

Abstract

BackgroundDepressive symptoms could be similarly expressed in bipolar and unipolar disorder. However, changes in cognition and brain networks might be quite distinct. We aimed to find out the difference in the neural mechanism of impaired working memory in patients with bipolar and unipolar disorder.MethodAccording to diagnostic criteria of bipolar II disorder of the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) and assessments, 13 bipolar II depression (BP II), 8 unipolar depression (UD) patients and 15 healthy controls (HC) were recruited in the study. We used 2-back tasks and magnetic source imaging (MSI) to test working memory functions and get the brain reactions of the participants.ResultsCompared with HC, only spatial working memory tasks accuracy was significantly worse in both UD and BP II (p = 0.001). Pearson correlation showed that the stronger the FCs’ strength of MFG-IPL and IPL-preSMA, the higher accuracy of SWM task within left FPN in patients with UD (r = 0.860, p = 0.006; r = 0.752, p = 0.031). However, the FC strength of IFG-IPL was negatively correlated with the accuracy of SWM task within left FPN in patients with BP II (r = − 0.591, p = 0.033).ConclusionsOur study showed that the spatial working memory of patients with whether UD or BP II was impaired. The patterns of FCs within these two groups of patients were different when performing working memory tasks.

Highlights

Up to 60% of patients with bipolar disorder are misdiagnosed as unipolar disorder what may considerably increase the risks of switching to suicide and poorer treatment responses [1]
The Functional connectivity (FC) strength of Inferior frontal gyrus (IFG)-Inferior parietal lobule (IPL) was negatively correlated with the accuracy of spatial working memory (SWM) task within left frontoparietal network (FPN) in patients with BP Bipolar II depression (II) (r = − 0.591, p = 0.033)
Our study showed that the spatial working memory of patients with whether unipolar depression (UD) or bipolar II depression (BP II) was impaired

Summary

Introduction

Up to 60% of patients with bipolar disorder are misdiagnosed as unipolar disorder what may considerably increase the risks of switching to suicide and poorer treatment responses [1]. Bipolar and unipolar disorder are sometimes confused in clinical practice which both could be manifested as symptoms of depression. Depressive symptoms may be either a risk factor or prodrome for cognitive deficits [2]. Cognitive deficit is one of the common symptoms of both bipolar and unipolar depression, even seems to be present in individuals in the remitted state [3, 4]. Our and other’s previous studies suggested that decreased working memory performance in bipolar and unipolar disorder reflected neurofunctional deficits [6, 7]. Depressive symptoms could be expressed in bipolar and unipolar disorder. We aimed to find out the difference in the neural mechanism of impaired working memory in patients with bipolar and unipolar disorder

Objectives

Methods

Results