Disentangling Working Memory Functioning in Mood States of Bipolar Disorder: A Systematic Review

Abstract

Working memory (WM) deficits are often reported in patients with Bipolar Disorder (BD). However, it is not clear about the nature of these WM deficits (update or serial order processes) and their association with each BD states (euthymic, mania, and depressive). This review investigated the association between BD patient's states and the functioning of WM components. For this purpose, we carried out a systematic review fulfilling a search in the databases Medline, Scopus, SciELO, and Web of Science using specific terms in the abstracts of the articles that generated 212 outcomes in the restricted period from 2005 to 2016. Twenty-three papers were selected, completely read, and analyzed using PICOS strategy. The mood episodes predicted deficits in different components of WM in BD patients (the phonological loop or visuospatial sketchpad) and were associated with different WM processes (updating and serial recall). Lower cognitive scores persist even in remission of symptoms. This result suggests that WM deficit apparently is stage-independent in BD patients. Furthermore, findings suggest that the neutral point on Hedonic Detector component of WM could be maladjusted by BD.

Executive functions and memory in bipolar disorders I and II: new insights from meta‐analytic results

“…All remaining effect sizes were classified as medium. The analysis of composite scores within each domain revealed that effect sizes were numerically larger for verbal than visual measures of both working memory and episodic memory, corroborating previous findings in the literature (11,13). However, heterogeneity was also larger for verbal memory instruments than those measuring visual memory.…”

“…The effect including the outlier was calculated at g = 0.54 (95% CI: 0.34-0.74). 13 One outlier removed. The effect including the outlier was calculated at g = 0.58 (95% CI: 0.25-0.91).…”

“…Yet the small number of studies involving BDII limits the strength of this conclusion: Several reviews explicitly mention their inability to compare BDI and BDII due to the absence of eligible studies in the literature (11,12). Others retrieve as few as one single study involving this particular disorder (1,13). As such, further investigation is needed to shed light on cognitive differences between BD subtypes.…”

Effects of mood episodes and comorbid anxiety on neuropsychological impairment in patients with bipolar spectrum disorder

“…Moreover, the significant deficits in working and verbal memory suggest an impact on frontal lobe functioning, disruption of frontal–subcortical or mesolimbic circuitry, or partial executive dysfunction (Ferrier et al., 1999). Soraggi‐Frez, Santos, Albuquerque, and Malloy‐Diniz (2017) carried out a comprehensive review and suggested that working memory deficit is more likely to be state‐independent in BD, indicating that mood episodes are associated with working memory impairment (Soraggi‐Frez et al., 2017). Working memory is sometimes referred to be part of executive function and has been reported to be impaired in BD patients as well as in AD patients (Soraggi‐Frez et al., 2017).…”

Abnormal perfusion fluctuation and perfusion connectivity in bipolar disorder measured by dynamic arterial spin labeling

“…Anterior cingulate cortex (ACC) and orbitofrontal cortex (OFC) in the PFC, known to be involved in the cognitive and emotional control, are among the investigated regions of BD deficits. In fact, BD patients have shown deficits in the ACC and OFC regions from brain structural, functional, neuropathological and as inferred indirectly from neuropsychological studies . Altered connectivity with the ACC and OFC regions has been reported sporadically in BD at rest or during challenge tasks .…”