Neural correlates of working memory function in euthymic people with bipolar disorder compared to healthy controls: A systematic review and meta-analysis

A systematic review of the biomarkers associated with cognition and mood state in bipolar disorder

BACKGROUND

Bipolar disorder (BD) is a severe psychiatric disorder characterized by changes in mood that alternate between (hypo) mania or depression and mixed states, often associated with functional impairment and cognitive dysfunction. But little is known about biomarkers that contribute to the development and sustainment of cognitive deficits. The aim of this study was to review the association between neurocognition and biomarkers across different mood states.

METHOD

Search databases were Web of Science, Scopus and PubMed. A systematic review was carried out following the PRISMA guidelines. Risk of bias was assessed with the Newcastle-Ottawa Scale. Studies were selected that focused on the correlation between neuroimaging, physiological, genetic or peripheral biomarkers and cognition in at least two phases of BD: depression, (hypo)mania, euthymia or mixed. PROSPERO Registration No.: CRD42023410782.

RESULTS

A total of 1824 references were screened, identifying 1023 published articles, of which 336 were considered eligible. Only 16 provided information on the association between biomarkers and cognition in the different affective states of BD. The included studies found: (i) Differences in levels of total cholesterol and C reactive protein depending on mood state; (ii) There is no association found between cognition and peripheral biomarkers; (iii) Neuroimaging biomarkers highlighted hypoactivation of frontal areas as distinctive of acute state of BD; (iv) A deactivation failure has been reported in the ventromedial prefrontal cortex (vmPFC), potentially serving as a trait marker of BD.

CONCLUSION

Only a few recent articles have investigated biomarker-cognition associations in BD mood phases. Our findings underline that there appear to be central regions involved in BD that are observed in all mood states. However, there appear to be underlying mechanisms of cognitive dysfunction that may vary across different mood states in BD. This review highlights the importance of standardizing the data and the assessment of cognition, as well as the need for biomarkers to help prevent acute symptomatic phases of the disease, and the associated functional and cognitive impairment.

Cluster analysis exploring the impact of childhood neglect on cognitive function in patients with bipolar disorder

BACKGROUND

Bipolar disorder (BD) is a severe mental disorder related to neurocognitive deficits. Exposure to childhood trauma is associated with worse cognitive performance. Different compositions of childhood trauma in BD and their impacts on cognition are rarely reported.

METHODS

We used the Brief Assessment of Cognition in Affective Disorders (BAC-A) to assess cognitive performance and the Chinese version of the Short Form of the Childhood Trauma Questionnaire (C-CTQ-SF) to assess childhood trauma experience among 55 euthymic BD patients. Cluster analysis was applied to dissect their childhood trauma experiences, which revealed three distinct clusters: a low trauma group, neglect-focus group, and multiple-trauma-experience group. We compared the cognitive function between the three clusters and used a generalized linear model to evaluate the impact of childhood neglect on cognitive domains.

RESULTS

The neglect-focus cluster showed prominent exposures to physical and emotional neglect (41.8%). BD patients in this cluster performed worse in BAC-A compared with patients in the multiple trauma cluster, especially in working memory and processing speed. The neglect-focus group revealed a significant negative effect on the composite score (ß = -0.904, p = 0.025) and working memory (ß = -1.150, p = 0.002) after adjusting sex, age, education year, BMI and total psychotropic defined daily dose.

CONCLUSIONS

Distinct patterns of childhood trauma experience are seen in BD patients and are related with different cognitive profiles. Early exposure of neglect-focus trauma was associated with the worst cognitive performance in current study. Further studies investigating the intensity of the neglect, as well as individual resilience and coping mechanisms in BD, are warranted.

A comparative study of cognitive function in young patients with bipolar disorder with and without non-suicidal self-injury

OBJECTIVE

Bipolar disorder (BD) is a chronic mental disorder characterized by alternating or mixed episodes of mania or hypomania and depression. Cognitive function impairment is a frequent associated feature of the disease. While many BD patients also engage in non-suicidal self-injury (NSSI), there is a lack of studies on the cognitive function of BD patients with NSSI. This study aimed to evaluate cognitive functioning of BD patients with NSSI and provide a clinical basis for the differential diagnosis and treatment of BD and NSSI.

METHODS

A total of 60 BD patients with NSSI, 60 BD patients without NSSI, and 60 healthy controls (HC) were selected for the study. All participants met the inclusion criteria and were not taking any medications, excluding the potential effects of medication on cognitive functions. The following neurocognitive tests were used to measure the cognitive functions in areas such as speed of processing, reasoning and problem solving, attention/vigilance, working memory, visual learning, and verbal learning: The Trail Making Test (TMT), Category Fluency, Digit Symbol Coding Test (DSCT), Brief Visuospatial Memory Test-Revised (BVMT-R), The Neuropsychological Assessment Battery Mazes (NABM), Wechsler Memory Scale Third Edition Spatial Span Test (WMS III-SST), Hopkins Verbal Learning Test-Revised (HVLTR) and Continuous Performance Test and Identical Prs (CPT-IP).

RESULTS

The findings indicated that BD patients with NSSI exhibited cognitive impairment in all measured cognitive domains. On the other hand, BD patients without NSSI showed less pronounced impairment in terms of speed of processing, but exhibited significant cognitive impairment in the remaining five areas compared to the HC group.

CONCLUSION

The study underscores the presence of cognitive impairment in BD, and the cognitive impairment is more severe in BD patients with NSSI compared to those without NSSI. In conclusion, both individuals with NSSI and those without NSSI in BD exhibit cognitive impairment, which provides ideas and strategies for using cognitive-behavioral therapy to treat BD and NSSI.

Cortical alterations in relatives of patients with bipolar disorder: A review of magnetic resonance imaging studies

INTRODUCTION

Bipolar disorder (BD) is a severe mental disorder characterized by high heritability rates. Widespread brain cortical alterations have been reported in BD patients, mostly involving the frontal, temporal and parietal regions. Importantly, also unaffected relatives of BD patients (BD-RELs) present abnormalities in cortical measures, which are not influenced by disease-related factors, such as medication use and illness duration. Here, we collected all available evidence on cortical measures in BD-RELs to further our knowledge on the potential cortical alterations associated with the vulnerability and the resilience to BD.

METHODS

A search on PubMed, Web of Science and Scopus was performed to identify neuroimaging studies exploring cortical alterations in BD-RELs, including cortical thickness (CT), surface area (SA), gyrification (GI) and cortical complexity. Eleven studies were included. Of these, five assessed CT, five examined CT and SA and one explored CT, SA and GI.

RESULTS

Overall, a heterogeneous pattern of cortical alterations emerged. The areas more consistently linked with genetic liability for BD were the prefrontal and sensorimotor regions. Mixed evidence was reported in the temporal and cingulate areas.

LIMITATIONS

The small sample size and the heterogeneity in terms of methodologies and the characteristics of the participants limit the generalizability of our results.

CONCLUSIONS

Our findings suggest that the genetic liability for BD is related to reduced CT in the prefrontal cortex, which might be a marker of risk for BD, and increased CT within the sensorimotor cortex, which could represent a marker of resilience.

The Different Impact of Depressive or Manic First-episode on Pediatric Bipolar Disorder Patients: Evidence From Resting-state fMRI

Bipolar disorder may begin as depression or mania, which can affect the treatment and prognosis of bipolar disorder. However, the physiological and pathological differences of pediatric bipolar disorder (PBD) patients with different onset symptoms are not clear. The purpose of this study was to investigate the differences of clinical, cognitive function and intrinsic brain networks in PBD patients with first-episode depression and first-episode mania. A total of 63 participants, including 43 patients and 20 healthy controls, underwent resting-state fMRI scans. PBD patients were classified as first-episode depressive and first-episode manic based on their first-episode symptoms. Cognitive tests were used to measure attention and memory of all participants. Independent component analysis (ICA) was used to extract the salience network (SN), default-mode network (DMN), central executive network (ECN) and limbic network (LN) for each participant. Spearman rank correlation analysis was performed between abnormal activation and clinical and cognitive measures. The results showed that there were differences in cognitive functions such as attention and visual memory between first-episode depression and mania, as well as differences activation in anterior cingulate cortex (ACC), posterior cingulate cortex (PCC), precuneus, inferior parietal cortex and parahippocampus. And significant associations of brain activity with clinical assessments or cognition were found in different patients. In conclusion, we found differential impairments in cognitive and brain network activation in first-episode depressive and first-episode manic PBD patients, and correlations were found between these impairments. These evidences may shed light on the different developmental paths of bipolar disorder.

Disrupted network switching in euthymic bipolar disorder: Working memory and self-referential paradigms

BACKGROUND

Patients with bipolar disorder (BD) frequently suffer from neurocognitive deficits that can persist during periods of clinical stability. Specifically, impairments in executive functioning such as working memory and in self-processing have been identified as the main components of the neurocognitive profile observed in euthymic BD patients. The study of the neurobiological correlates of these state-independent alterations may be a prerequisite to develop reliable biomarkers in BD.

METHODS

A sample of 27 euthymic BD patients and 25 healthy participants (HC) completed working memory and self-referential functional Magnetic Resonance Imaging (fMRI) tasks. Activation maps obtained for each group and contrast images (i.e., 2-back > 1-back/self > control) were used for comparisons between patients and HC.

RESULTS

Euthymic BD patients, in comparison to HC, showed a higher ventromedial prefrontal cortex activation during working memory, a result driven by the lack of deactivation in BD patients. In addition, euthymic BD patients displayed a greater dorsomedial and dorsolateral prefrontal cortex activation during self-reference processing.

LIMITATIONS

Pharmacotherapy was described but not included as a confounder in our models. Sample size was modest.

CONCLUSION

Our findings revealed a lack of deactivation in the anterior default mode network (aDMN) during a working memory task, a finding consistent with prior research in BD patients, but also a higher activation in frontal regions within the central executive network (CEN) during self-processing. These results suggest that an imbalance of neural network dynamics underlying external/internal oriented cognition (the CEN and the aDMN, respectively) may be one of the first reliable biomarkers in euthymic bipolar patients.

Working memory updating in individuals with bipolar and unipolar depression: fMRI study

Understanding neurobiological characteristics of cognitive dysfunction in distinct psychiatric disorders remains challenging. In this secondary data analysis, we examined neurobiological differences in brain response during working memory updating among individuals with bipolar disorder (BD), those with unipolar depression (UD), and healthy controls (HC). Individuals between 18-45 years of age with BD (n = 100), UD (n = 109), and HC (n = 172) were scanned using fMRI while performing 0-back (easy) and 2-back (difficult) tasks with letters as the stimuli and happy, fearful, or neutral faces as distractors. The 2(n-back) × 3(groups) × 3(distractors) ANCOVA examined reaction time (RT), accuracy, and brain activation during the task. HC showed more accurate and faster responses than individuals with BD and UD. Difficulty-related activation in the prefrontal, posterior parietal, paracingulate cortices, striatal, lateral occipital, precuneus, and thalamic regions differed among groups. Individuals with BD showed significantly lower difficulty-related activation differences in the left lateral occipital and the right paracingulate cortices than those with UD. In individuals with BD, greater difficulty-related worsening in accuracy was associated with smaller activity changes in the right precuneus, while greater difficulty-related slowing in RT was associated with smaller activity changes in the prefrontal, frontal opercular, paracingulate, posterior parietal, and lateral occipital cortices. Measures of current depression and mania did not correlate with the difficulty-related brain activation differences in either group. Our findings suggest that the alterations in the working memory circuitry may be a trait characteristic of reduced working memory capacity in mood disorders. Aberrant patterns of activation in the left lateral occipital and paracingulate cortices may be specific to BD.

Chronic Stress Is Associated with Reduced Mindful Acceptance Skills but Not with Mindful Attention Monitoring: A Cross-Sectional Study

Mindfulness-based interventions (MBIs) are effective in reducing chronic stress, but their therapeutic mechanisms are unclear. One possibility is that MBIs act by re-training attention monitoring and acceptance skills that have been impaired by chronic stress exposure. However, little research has investigated the association between chronic stress, monitoring, and acceptance. In this cross-sectional study we hypothesised observing correlations between stress, and (impaired) monitoring and acceptance. Moreover, we exploratively compared the magnitude of the correlations between chronic stress and four acceptance measures. Finally, we explored whether the association between stress and monitoring is moderated by acceptance. Eighty-five adults participated in the study and completed self-reported chronic stress and acceptance questionnaires and a mindful attention behavioural task. The results revealed that chronic stress was associated with reduced acceptance (all ps < 0.01) but not with monitoring. Exploratory analyses revealed no differences in the magnitude of the correlations between stress and each acceptance measure, except for the combined facets of mindfulness acceptance subscales and nonreactivity subscale (p = 0.023). Further analyses revealed a significant negative association between stress and the interaction between acceptance and the target detection component of monitoring (p = 0.044). Surprisingly, these results show that stress is associated with reduced monitoring at higher levels of acceptance. Theory-driven intervention studies are warranted to complement our results.