Comparative neurocognitive effects of lithium and anticonvulsants in long-term stable bipolar patients

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.

Assessing social cognition in patients with schizophrenia and healthy controls using the reading the mind in the eyes test (RMET): a systematic review and meta-regression

The reading the mind in the eyes test (RMET) - which assesses the theory of mind component of social cognition - is often used to compare social cognition between patients with schizophrenia and healthy controls. There is, however, no systematic review integrating the results of these studies. We identified 198 studies published before July 2020 that administered RMET to patients with schizophrenia or healthy controls from three English-language and two Chinese-language databases. These studies included 41 separate samples of patients with schizophrenia (total n = 1836) and 197 separate samples of healthy controls (total n = 23 675). The pooled RMET score was 19.76 (95% CI 18.91-20.60) in patients and 25.53 (95% CI 25.19-25.87) in controls (z = 12.41, p < 0.001). After excluding small-sample outlier studies, this difference in RMET performance was greater in studies using non-English v. English versions of RMET (Chi [Q] = 8.54, p < 0.001). Meta-regression analyses found a negative association of age with RMET score and a positive association of years of schooling with RMET score in both patients and controls. A secondary meta-analysis using a spline construction of 180 healthy control samples identified a non-monotonic relationship between age and RMET score - RMET scores increased with age before 31 and decreased with age after 31. These results indicate that patients with schizophrenia have substantial deficits in theory of mind compared with healthy controls, supporting the construct validity of RMET as a measure of social cognition. The different results for English versus non-English versions of RMET and the non-monotonic relationship between age and RMET score highlight the importance of the language of administration of RMET and the possibility that the relationship of aging with theory of mind is different from the relationship of aging with other types of cognitive functioning.

Characterisation of Deficits and Sex Differences in Verbal and Visual Memory/Learning in Bipolar Disorder

OBJECTIVE

Cognitive impairment is consistently reported in bipolar disorder (BD), but few studies have characterised which memory component processes are affected. Further, it is unknown whether the component processes underlying memory impairment are moderated by sex. The present study examined diagnosis and sex differences in both verbal and visual memory/learning domains in patients with BD and psychiatrically healthy controls.

METHOD

Verbal and visual memory/learning were measured using the Hopkins Verbal Learning Test-Revised (HVLT-R) and Brief Visuospatial Memory Test-Revised (BVMT-R). 114 patients with BD (n = 50 males, n = 64 females), were compared to 105 psychiatrically healthy controls (n = 42 males, n = 63 females).

RESULTS

Patients with BD had worse performance in verbal and visual immediate and total recall, verbal and visual delayed free recall, and verbal recognition discrimination scores, but there were no group differences in learning slopes and cumulative learning index scores. There were trends for BD females to outperform BD males in visual memory/learning free recall and cumulative learning, but these results did not survive multiple testing correction. These findings did not change in a secondary sensitivity analysis comparing only strictly euthymic BD patients to controls (n = 64).

CONCLUSION

The present study found trait-like verbal and visual memory/learning impairment in BD that was attributable to deficient encoding and/or consolidation processes rather than deficits in learning. We did not find marked sex differences in either visual or verbal memory/learning measures, although some trend level effects were apparent and deserve exploration in future studies.

BIPOLAR DISORDER, MOOD STABILIZERS AND COGNITIVE FLEXIBILITY: TRANSLATIONALLY DISSECTING ILLNESS FROM DRUG EFFECTS

Bipolar disorder (BD) effects on cognition are confounded by the putative cognitive impact of its major pharmacological treatments, given the neurotrophic potential of mood stabilizers, particularly lithium. We examined the area of cognitive flexibility (CF), aiming to disentangle BD from medication effects, using translational methodology. CF was assessed by CANTAB-IED (intra- extra-dimensional shift; Study 1, euthymic BD participants) and its animal analogue (Study 2, rats). Both studies included groups (1) control, (2) lithium, chronic, current treatment (LI-CHRON-C, A: >2 years, N=32; B: 2 months, N=11); (3) valproate, chronic, current treatment (VPA-CHRON-C, A: >2 years, N=30; B: 2 months, N=12). Study 2 included 2 additional groups; Group 4: LI-CHRON-PAST (2 months, stopped 1 month pretest, N=13); Group 5: LI-ACUTE (LI on test days only, N=13). In Study 1, neither total nor stage (discrimination: D; reversal R; intra- extra-dimensional shifts: IED) IED errors differed between groups [(Kruskal-Wallis: H(2, N= 94) 0.95 > p > 0.65]. Similarly in Study 2, errors did not differentiate the 5 pharmacological groups. Differences emerged only between LI-ACUTE and Controls in response latencies (D, R, IED ANOVAS: 0.002 > p > 0.0003; contrasts D, R: p = 0.002, 0.0001). In conclusion, LI and VPA BD patients were indistinguishable from Controls in IED errors, as were animals treated with LI-CHRON, current or past, or VPA-CHRON-C vs Controls. LI-ACUTE treatment produced significant latency deficits vs. Controls. Within the limitations of translational comparisons, our results suggest that the normal CF noted in euthymic BDs is not attributable to mood stabilizer effects.

Neuronal underpinnings of cognitive impairment in bipolar disorder: A large data-driven functional magnetic resonance imaging study

OBJECTIVES

Cognitive impairment occurs in approximately 50% of remitted patients with bipolar disorder (BD). However, there exists no treatment with replicated and robust efficacy on cognition in BD. This is partially due to limited insight into the neuronal underpinnings of cognitive impairment in these patients. This is the first study to investigate neuronal underpinnings of cognitive impairment in a large functional magnetic resonance imaging (fMRI) dataset comparing neural activity patterns between distinct neurocognitive subgroups of partially or fully remitted patients with BD.

METHODS

Patients (n = 153) and healthy controls (HC) (n = 52) underwent neuropsychological assessment and fMRI, during which they performed a verbal N-back working memory (WM) task. Based on hierarchical cluster analysis of neuropsychological test performance, patients were grouped into one of two neurocognitive subgroups (cognitively impaired, n = 91; cognitively normal compared to HC, n = 62) that were compared on WM-related neural activity.

RESULTS

Cognitively impaired patients displayed WM-related hypo-activity in left dorsolateral prefrontal cortex and frontal and parietal regions within a cognitive control network (CCN) as well as hyper-activity in the default mode network (DMN) compared to cognitively normal patients. In contrast, cognitively normal patients only exhibited hypo-activity within a small cluster in the superior frontal gyrus relative to HC.

CONCLUSIONS

Cognitive impairment in BD seems to originate from a failure to recruit key regions in the CCN and to suppress task-irrelevant DMN activity during cognitive performance. These results highlight modulation of aberrant dorsal prefrontal and DMN activity as a putative target for pro-cognitive treatment in BD.

The effect of concomitant benzodiazepine use on neurocognition in stable, long-term patients with bipolar disorder

OBJECTIVE

Neurocognitive dysfunction is a common feature of bipolar disorder even in euthymia, and psychopharmacological treatment could have an effect on cognition. Long-term prescription of benzodiazepines in bipolar disorder is a common practice, and their effect on neurocognition has not been well studied in this population. The aim of this study was to evaluate the impact of concomitant benzodiazepine long-term use on neurocognitive function in stable euthymic bipolar disorder patients.

METHODS

Seventy-three euthymic bipolar disorder outpatients and 40 healthy individuals were assessed using a neurocognitive battery. Patients were classified in two groups according to the presence of benzodiazepines in their treatment: the benzodiazepine group (n = 34) and the non- benzodiazepine group (n = 39). Neurocognitive performance was compared between the groups using a multivariate analysis of covariance, considering age, number of depressive episodes, adjuvant antipsychotic drugs, Young Mania Rating Scale score and Hamilton Depression Rating Scale score as covariates.

RESULTS

Both bipolar disorder groups (benzodiazepine and non-benzodiazepine) showed an impairment in memory domains (Immediate Visual Memory [p = 0.013], Working Memory [p < 0.001], and Letter-Number Sequence [p < 0.001] from the Wechsler Memory Scale-Revised-III) and slower processing speed functions (Stroop Colour [p < 0.001]) relative to the control group. Nevertheless, the benzodiazepine group showed a greater impairment in executive functions (Conceptual Level Responses [p = 0.024] from the Wisconsin Card Sorting Test and Frontal Assessment Battery [p = 0.042]).

CONCLUSION

Although memory and processing speed impairments were found in bipolar disorder, regardless of their benzodiazepine treatment, benzodiazepine users presented additional neurocognitive impairments in terms of executive functioning. These findings support restricted prescription of benzodiazepines in individuals with bipolar disorder.

Neuroprogression as an Illness Trajectory in Bipolar Disorder: A Selective Review of the Current Literature

Bipolar disorder (BD) is a chronic and disabling psychiatric condition that is linked to significant disability and psychosocial impairment. Although current neuropsychological, molecular, and neuroimaging evidence support the existence of neuroprogression and its effects on the course and outcome of this condition, whether and to what extent neuroprogressive changes may impact the illness trajectory is still poorly understood. Thus, this selective review was aimed toward comprehensively and critically investigating the link between BD and neurodegeneration based on the currently available evidence. According to the most relevant findings of the present review, most of the existing neuropsychological, neuroimaging, and molecular evidence demonstrates the existence of neuroprogression, at least in a subgroup of BD patients. These studies mainly focused on the most relevant effects of neuroprogression on the course and outcome of BD. The main implications of this assumption are discussed in light of specific shortcomings/limitations, such as the inability to carry out a meta-analysis, the inclusion of studies with small sample sizes, retrospective study designs, and different longitudinal investigations at various time points.

Therapeutic potential of targeting G protein-gated inwardly rectifying potassium (GIRK) channels in the central nervous system

G protein-gated inwardly rectifying potassium channels (Kir3/GirK) are important for maintaining resting membrane potential, cell excitability and inhibitory neurotransmission. Coupled to numerous G protein-coupled receptors (GPCRs), they mediate the effects of many neurotransmitters, neuromodulators and hormones contributing to the general homeostasis and particular synaptic plasticity processes, learning, memory and pain signaling. A growing number of behavioral and genetic studies suggest a critical role for the appropriate functioning of the central nervous system, as well as their involvement in many neurologic and psychiatric conditions, such as neurodegenerative diseases, mood disorders, attention deficit hyperactivity disorder, schizophrenia, epilepsy, alcoholism and drug addiction. Hence, GirK channels emerge as a very promising tool to be targeted in the current scenario where these conditions already are or will become a global public health problem. This review examines recent findings on the physiology, function, dysfunction, and pharmacology of GirK channels in the central nervous system and highlights the relevance of GirK channels as a worthful potential target to improve therapies for related diseases.

A genetic window to auditory-verbal problems in bipolar disorder

Bipolar disorder is a high prevalent psychiatric condition entailing recurrent episodes of elevated mood and depression, but also diverse cognitive problems. One deficit observed in patients concerns to auditory-verbal processing. Being a hereditary condition with a complex genetic architecture, it is not clear which genes contribute to this deficit. We show that candidates for bipolar disorder significantly overlap with candidates for clinical conditions resulting from a deficit in the phonological loop of working memory, particularly, developmental dyslexia and specific language impairment. The overlapping genes are involved in aspects of brain development and function (particularly, brain oscillations) potentially underlying phonological processing and accordingly, emerge as promising candidates for auditory-verbal deficits in bipolar disorder.

Cognitive Impairment in Patients with Bipolar Disorder: Impact of Pharmacological Treatment

Bipolar disorder is an illness characterised by periods of elated and depressed mood. These mood episodes are associated with changes in cognitive function and there is evidence to suggest that cognitive dysfunction persists during euthymia. The extent to which this is a function of the illness or a result of treatment is less clear. In this narrative review, we explore the impact of commonly used medications for bipolar disorder on cognitive function. Specific impairments in executive function and verbal memory have been noted in bipolar disorder. The impact of pharmacological treatments upon cognitive function is mixed with a number of studies reporting conflicting results. Interpretation of the data is further complicated by the variety of cognitive tests employed, study design, the relatively small numbers of patients included and confounding by indication. Overall, there is some evidence that while lithium improves some cognitive domains, it impedes others. Antipsychotics may be deleterious to cognition, although this may relate to the patient population in which they are prescribed. Sodium valproate is also associated with worse cognitive outcomes, while the impact of other antiepileptics is unclear. Overall the quality of evidence is poor and is derived from a relatively small number of studies that often do not account for the significant heterogeneity of the disorder or common comorbidities. The use of consistent methodologies and measures of cognition across studies, as well as in naturalistic settings, would enable more certain conclusions to be drawn.

Neuroanatomical Dysconnectivity Underlying Cognitive Deficits in Bipolar Disorder

BACKGROUND

Graph theory applied to brain networks is an emerging approach to understanding the brain's topological associations with human cognitive ability. Despite well-documented cognitive impairments in bipolar disorder (BD) and recent reports of altered anatomical network organization, the association between connectivity and cognitive impairments in BD remains unclear.

METHODS

We examined the role of anatomical network connectivity derived from T1- and diffusion-weighted magnetic resonance imaging in impaired cognitive performance in individuals with BD (n = 32) compared with healthy control individuals (n = 38). Fractional anisotropy- and number of streamlines-weighted anatomical brain networks were generated by mapping constrained spherical deconvolution-reconstructed white matter among 86 cortical/subcortical bilateral brain regions delineated in the individual's own coordinate space. Intelligence and executive function were investigated as distributed functions using measures of global, rich-club, and interhemispheric connectivity, while memory and social cognition were examined in relation to subnetwork connectivity.

RESULTS

Lower executive functioning related to higher global clustering coefficient in participants with BD, and lower IQ performance may present with a differential relationship between global and interhemispheric efficiency in individuals with BD relative to control individuals. Spatial recognition memory accuracy and response times were similar between diagnostic groups and associated with basal ganglia and thalamus interconnectivity and connectivity within extended anatomical subnetworks in all participants. No anatomical subnetworks related to episodic memory, short-term memory, or social cognition generally or differently in BD.

CONCLUSIONS

Results demonstrate selective influence of subnetwork patterns of connectivity in underlying cognitive performance generally and abnormal global topology underlying discrete cognitive impairments in BD.

Conventional mood stabilizers and/or second-generation antipsychotic drugs in bipolar disorders: A population-based comparison of risk of treatment failure

BACKGROUND

The study compared treatment failure when using three therapeutic strategies in bipolar disorders: (i) mood stabilizers (MSs: lithium, valpromide, divalproate, carbamazepine, lamotrigine) without second-generation antipsychotic (SGAP); (ii) SGAPs (aripiprazole, olanzapine, risperidone, quetiapine) without MS; (iii) combination of MSs and SGAPs.

METHODS

A historical cohort study was conducted using the French national healthcare databases in 20,086 outpatients aged 21+, newly treated with one of the three treatment strategies in 2011-2012, and diagnosed with a bipolar disorder. A composite outcome was based on indicators of treatment failure identified over 12 months: treatment discontinuation, switch or addition, psychiatric hospitalisation, suicide attempt, and death. For each strategy, the cumulative incidence of treatment failure was calculated while adjusting for covariates by propensity score weighting.

RESULTS

A total of 8,225 patients (40.9%) were newly dispensed MSs, 9,342 (46.5%) SGAPs, and 2,519 (12.5%) both MSs and SGAPs. The one-year adjusted cumulative incidence of treatment failure was 75.7% (95%CI 74.9;76.3) in patients using MSs, 75.3% (74.6;76.0) in patients using SGAPs, and 60.5% (58.3;62.6) in patients with the combination. The adjusted difference in incidence for SGAPs compared with MSs was -0.40% (-1.4;0.6 p = 0.4) in the whole population, -2.2% (-3.3; -1.2 p < 0.002) in patients under 65 years and +6.7% (4.1;9.1 p < 0.002) in patients 65 years and over.

LIMITATIONS

Combinations of MSs and SGAPs could not be directly compared with MS or SGAP monotherapies.

CONCLUSIONS

One-year treatment failure was high. Overall, no difference in treatment failure was observed between MS or SGAP strategy but differences might exist depending on age.

Attention Deficits in a Comorbidity-Free Sample of Euthymic Pediatric Bipolar Disorder

Attention deficits are considered one of the potential endophenotypic markers of Bipolar Disorder (BD). Pediatric bipolar disorder (PBD) likely has stronger genetic underpinnings than adult onset BD; therefore, demonstrating attention deficits in PBD can be both strategic and convincing in attesting their status as one of the potential endophenotypic markers of BD. However, unlike adult literature, uncertainty exists regarding the magnitude of attention deficits in PBD. In this regard, one key unresolved question is the potential impact of attention deficit hyperactivity disorder (ADHD). The main goal of the study was to examine attention deficits in a comorbidity-free sample of euthymic PBD patients. Thirty (21 boys, 9 girls) remitted PBD patients without co-morbidity and thirty age (<17 years), sex, handedness, and Full-Scale IQ matched control subjects were compared on performance on attention tasks. Working memory (WM), which might potentially confound with the attention task performances, was also examined. Compared to controls, PBD patients performed poorly on various tests of attention, but not on any WM tasks. Further, it was found that observed attention deficits were independent of residual mood symptoms, medication effect or illness characteristics. Such attention deficits in this comorbidity-free PBD sample further endorses its status as an endophenotypic marker of bipolar disorders and establishes continuity with deficits found in adult bipolar patients.

Neuropsychological Functioning in Euthymic Phase of Bipolar Affective Disorder

BACKGROUND

A substantial proportion of euthymic bipolar disorder patients have neuropsychological impairment which can have a significant impact on the overall functional recovery.

MATERIALS AND METHODS

A total of 60 bipolar disorder patients, currently in euthymic phase for the last 3 months with minimum duration of illness 2 years and current Young Mania Rating Scale <7 and Hamilton Depression Rating Scale <6, currently on medications were administrated various neuropsychological tests.

RESULTS

Approximately half of the patients have neuropsychological impairments in the areas of mental speed, sustained attention, verbal fluency, working memory, set shifting, verbal and visual memory, and visual-constructional ability.

CONCLUSION

Findings of the current study provides evidence of neuropsychological impairment in euthymic bipolar disorder patients, and type of medications also has an impact on neuropsychological functions.

Increased reward-oriented impulsivity in older bipolar patients: A preliminary study

OBJECTIVE

Impulsivity is a well-established trait of bipolar disorder (BD) that persists across mood phases. It is, however, still unknown whether, in BD, impulsivity remains stable or varies in intensity over the lifespan. This cross-sectional study compared impulsive behavior in older euthymic BD patients and healthy individuals using a range of self-rating and behavioral measures of impulsivity.

METHODS

28 BD patients (56.07 ± 4.08 years, 16 women) and 15 healthy controls (HC; 55.1 ± 3.95 years, 6 women) were administered the Barratt Impulsivity Scale (BIS) and selected tasks of the Cambridge Neuropsychological Test Automated Batter (CANTAB) reflecting impulsivity. Multivariate analysis of variance controlled for age compared impulsivity measures across BD and HC.

RESULTS

BD patients displayed poor decision making, risk taking, and increased delay aversion. Other measures of impulsivity such as response inhibition, sustained cognitive control, and BIS scores were, overall, comparable between BD and HC.

CONCLUSIONS

These preliminary findings suggest that, in BD, aspects of impulsivity related to reward-based decision making persist into late adulthood. Large scale, longitudinal studies are needed to evaluate the relationship of age to impulsivity over time, and explore the link between impulsivity and illness progression in elderly individuals with BD.

Cognitive function, treatment response to lithium, and social functioning in Japanese patients with bipolar disorder

OBJECTIVES

Patients with bipolar disorder often suffer from cognitive impairment that significantly influences their functional outcome. However, it remains unknown whether lithium has a central role in cognition and functional outcome. We examined whether cognition and functional outcome were predicted by demographic and clinical variables, including the response to lithium, in lithium-treated patients with bipolar disorder.

METHODS

We evaluated 96 lithium-treated euthymic patients with bipolar disorder and 196 age- and-gender-matched healthy controls, using the Brief Assessment of Cognition in Schizophrenia (BACS). The patients were also assessed using the Social Functioning Scale (SFS) and "The Retrospective Criteria of Long-Term Treatment Response in Research Subjects with Bipolar Disorder" (Alda) scale, which was evaluated as either a continuous measure of the total scale or a dichotomous criterion.

RESULTS

Multiple regression analysis revealed two key findings: first, that the premorbid intelligence quotient, age, and number of mood episodes were predictors of the BACS composite score; and, second, that the BACS composite score, negative symptoms, and continuous measure on the total Alda scale (but not its dichotomy) predicted the total SFS score. Structural equation modeling (SEM) was used to confirm these findings, and additionally revealed that the Alda scale was significantly associated with negative symptoms and also the number of mood episodes, regardless of how it was evaluated.

CONCLUSIONS

SEM delineated how demographic and clinical variables, cognitive performance, and response to lithium treatment were causally associated with, and converged on, social function. The putative role of the Alda scale for social function warrants further study.

[Cognitive deficits following brain tumor radiation therapy]

Brain radiation is an important treatment option for malignant and benign brain diseases. The possible acute or chronic impact of radiation therapy on cognitive performance is important for daily functioning and quality of life. A detailed evaluation of cognitive impairment is important in the context of how to control disease progression. The susceptibility of the hippocampus to radiation-induced neuronal damage and its important role in memory highlight that therapeutic strategies require precision medicine.

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

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.

Lithium and cognition in those with bipolar disorder

Although a percentage of patients report cognitive side-effects when taking lithium, it can be difficult to determine from the literature whether any cognitive changes reflect lithium itself, the lithium serum level, residual mood symptoms, the underlying nature of bipolar disorder, or biological alterations such as hypothyroidism. This review was carried out to synthesize and evaluate relevant literature examining any cognitive impact of lithium in those with bipolar disorder. The effect of lithium in those with bipolar disorder was examined across the cognitive domains of attention, psychomotor speed, processing speed, working memory, intellectual functioning, verbal memory, visual memory, and executive functioning by reviewing the published empirical literature. Any impact of hypothyroidism and lithium toxicity was also examined. The literature supports the conclusion that lithium has a distinct impact on psychomotor speed in participants with bipolar disorder. In contrast, there appears to be no impact on attention. Any impact of lithium on memory in patients with bipolar disorder is unclear as the literature is contradictory and any such effect may be overshadowed by the greater impact of residual mood symptoms. The impact on processing speed, intellectual abilities, and executive functioning also remains unclear. Several clinical management strategies are recommended.

The role of white matter in personality traits and affective processing in bipolar disorder

BACKGROUND

Bipolar disorder (BD) is characterized by affective processing bias and variations in personality traits. It is still unknown whether these features are linked to the same structural brain alterations. The aim of this study was to investigate relationships between specific personality traits, white matter (WM) properties, and affective processing in BD and HC.

METHODS

24 healthy controls (HC) and 38 adults with BDI (HC: 29.47 ± 2.23 years, 15 females; BDI: 32.44 ± 1.84 years, 20 females) completed clinical scales and the Big Five Inventory. They were also administered the Affective Go/No-Go (AGN) and the Rapid Visual Processing (RVP) tasks of the Cambridge Neuropsychological Test Automated Battery. Diffusion Tensor Imaging (DTI) assessed the microstructure of WM tracts.

RESULTS

In BDI measures of WM properties were reduced across all major brain white matter tracts. As expected, individuals with BDI reported greater neuroticism, lower agreeableness and conscientiousness, and made a greater number of errors in response to affective stimuli in the AGN task compared to HC. High neuroticism scores were associated with faster AGN latency, and overall reduced AGN accuracy in both HC and BDI. Elevated FA values were associated with reduced neuroticism and increased cognitive processing in HC but not in BDI.

CONCLUSIONS

Our findings showed important potential links between personality, affective processing and WM integrity in BD. In the future therapeutic interventions for BD using brain stimulation protocols might benefit from the use of DTI to target pathways underlying abnormal affective processing.

Structural and Functional Brain Correlates of Cognitive Impairment in Euthymic Patients with Bipolar Disorder

Introduction

Cognitive impairment in the euthymic phase is a well-established finding in bipolar disorder. However, its brain structural and/or functional correlates are uncertain.

Methods

Thirty-three euthymic bipolar patients with preserved memory and executive function and 28 euthymic bipolar patients with significant memory and/or executive impairment, as defined using two test batteries, the Rivermead Behavioural Memory Test (RBMT) and the Behavioural Assessment of the Dysexecutive Syndrome (BADS), plus 28 healthy controls underwent structural MRI using voxel-based morphometry (VBM). Twenty-seven of the cognitively preserved patients, 23 of the cognitively impaired patients and 28 controls also underwent fMRI during performance of the n-back working memory task.

Results

No clusters of grey or white matter volume difference were found between the two patient groups. During n-back performance, the cognitively impaired patients showed hypoactivation compared to the cognitively preserved patients in a circumscribed region in the right dorsolateral prefrontal cortex. Both patient groups showed failure of de-activation in the medial frontal cortex compared to the healthy controls.

Conclusions

Cognitive impairment in euthymic bipolar patients appears from this study to be unrelated to structural brain abnormality, but there was some evidence for an association with altered prefrontal function.