Differential executive functioning performance by phase of bipolar disorder

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.

Childhood trauma relates to worse memory functioning in bipolar disorder

BACKGROUND

Childhood trauma is commonly experienced by individuals diagnosed with bipolar disorder (BP). In BP, childhood trauma is related to a more severe clinical course, but its association with cognition remains unclear.

METHODS

This study evaluated 405 adult participants diagnosed with BP and 136 controls. Participants completed the Childhood Trauma Questionnaire and a comprehensive neuropsychological battery. High versus low childhood trauma was defined with one standard deviation above the control participant's mean Childhood Trauma Questionnaire score. Neuropsychological data was transformed into eight cognitive factors, including four executive functioning, auditory and visual memory, fine motor, and emotion processing. Multivariate analysis of covariance evaluated group differences in cognition, while adjusting for covariates.

RESULTS

There were significant differences among the three groups, F(16, 968) = 4.05, p < .001, Wilks' Λ = 0.88, partial η² = 0.06. Comparing the high and low trauma BP groups, high trauma was related to lower auditory and visual memory factor scores (p < .05). As compared to controls, the BP high trauma group had lower scores on six of eight factors (all p < .01), while the BP low trauma group had lower scores on four of eight factors (all p < .01).

LIMITATIONS

Analyses of factor score do not address which aspect of the memory process is affected and biomarkers may help guide interventions addressing underlying biological process.

CONCLUSIONS

Adults diagnosed with BP with higher childhood trauma have worse memory functioning, beyond the lower childhood trauma BP group, highlighting the importance of understanding the long-term cognitive outcomes of childhood trauma.

Peripheral insulin sensitivity predicting cognitive function in euthymic bipolar disorder patients

OBJECTIVE

High prevalence of insulin resistance (IR) has been reported in bipolar disorder (BD) patients. Importantly, impaired insulin sensitivity could modulate the course and treatment outcome in BD. Here, we hypothesized that insulin sensitivity could be potentially associated with the neurocognitive trajectory in euthymic BD. We aimed to examine differences in insulin sensitivity and executive function between BD patients and controls.

METHODS

Sixty-two patients with BD receiving mood stabilizer treatment and 62 controls, matching age, sex, and body mass index, were recruited in this study. Insulin sensitivity was estimated using the homeostasis model assessment of insulin resistance (HOMA-IR). The Wisconsin card-sorting test (WCST) was applied to test participants' ability to shift cognitive set. Group differences were measured and multivariate regression analysis was performed to examine relationships among factors.

RESULTS

The results indicated that the HOMA-IR (P = .048) value in the patients with BD were significantly higher than those in controls. With regards to executive function, the BD patients performed significantly poorer than the control subjects (P < .05). Moreover, the interaction effect between BD diagnosis and HOMA-IR value on the WCST-preservation errors was significant (P = .01), and post-hoc analyses showed that the cognitive abilities were worse in the BD patients with a higher IR than in the others groups.

CONCLUSION

Insulin sensitivity is associated with the neurocognitive performance in euthymic BD patients. Although the underlying mechanisms remain unclear, interventions to improve insulin sensitivity could potentially improve the functional outcome of BD.

Differential trajectory of cognitive functions in neurocognitive subgroups of newly diagnosed patients with bipolar disorder and their unaffected first-degree relatives - A longitudinal study

BACKGROUND

Cognitive impairments exist in a large proportion of remitted patients with bipolar disorder (BD). However, no study has investigated the cognitive trajectories across neurocognitive subgroups of patients or their unaffected first-degree relatives (UR).

METHODS

Newly diagnosed BD patients, UR and healthy controls (HC) underwent comprehensive cognitive testing at baseline and at 16-months follow-up. Hierarchical cluster analysis was conducted to identify homogeneous subgroups of patients based on their neurocognitive profile at baseline. Cognitive change across subgroups of patients and UR was assessed with linear mixed-model analyses.

RESULTS

Data from baseline and follow-up were collected from 152 patients, 53 UR and 135 HC. Patients were clustered into three discrete neurocognitive subgroups: 'cognitively normal' (43%), 'mild-moderately impaired' (33%) and 'globally impaired' (24%). While 'mild-moderately impaired' patients and HC showed normative cognitive improvement over time in global cognition (p < .001), 'globally impaired' patients showed greater improvement than all groups (p < .001), whereas 'cognitively normal' patients showed a lack of normative improvement (p = .17). UR of impaired patients showed a lack of normative improvement in executive functions (p = .01). 'Globally impaired' patients also presented with stable impairments in facial expression recognition and emotion regulation.

LIMITATIONS

Follow-up data was available for 62% of participants, possibly reflecting a selection bias.

CONCLUSIONS

The greater cognitive improvement in 'globally impaired' patients partly speaks against neuroprogression. However, the lack of normative improvement in 'cognitively normal' patients could indicate negative effects of illness. Further follow-up assessments are warranted to clarify whether lack of normative improvement in executive function in UR represents an illness risk-marker.

Cognitive factor structure and measurement invariance between healthy controls and patients with major depressive disorder

Cognitive impairments are crucial in functional outcomes of major depressive disorder (MDD). The effectiveness of currently available treatment methods for cognitive deficits is suboptimal. A cognitive test battery is often applied to evaluate cognition with multiple interrelated and difficult-to-interpret outcomes. Generating cognitive factor scores after the confirmation of a common cognitive structure and measurement invariance between healthy controls (HCs) and patients may aid in understanding cognition further. This methodology has been applied for several neuropsychiatric disorders, but not for MDD. Therefore, we conducted a series of exploratory factor analyses (EFA), confirmatory factor analyses (CFA), and multiple groups CFA (MGCFA) for a cognitive test battery in HCs and patients with MDD. The initial EFA of 106 HCs yielded a three-factor model-comprising attention, memory, and executive function. The CFA confirmed the initial model in other 94 HCs with revisions, which reasonably fit the cognitive data of 54 patients with MDD. MGCFA supported the measurement invariance of the determined model between HCs and patients with MDD. The associations of cognitive factor scores with age or education and the effect sizes of group differences in cognitive factor scores externally validated the determined model. In conclusion, this is the first study to demonstrate the measurement invariance of a cognitive model between HCs and patients with MDD using MGCFA. The measurement invariance substantiated valid group comparisons of factor scores and their relationships with other markers. The current results may be applicable for the development of improved treatment strategies for cognitive impairments in MDD.

Mathematical modeling of risk-taking in bipolar disorder: Evidence of reduced behavioral consistency, with altered loss aversion specific to those with history of substance use disorder

Bipolar disorder (BD) is associated with excessive pleasure-seeking risk-taking behaviors that often characterize its clinical presentation. However, the mechanisms of risk-taking behavior are not well-understood in BD. Recent data suggest prior substance use disorder (SUD) in BD may represent certain trait-level vulnerabilities for risky behavior. This study examined the mechanisms of risk-taking and the role of SUD in BD via mathematical modeling of behavior on the Balloon Analogue Risk Task (BART). Three groups-18 euthymic BD with prior SUD (BD+), 15 euthymic BD without prior SUD (BD-), and 33 healthy comparisons (HC)-completed the BART. We modeled behavior using 4 competing hierarchical Bayesian models, and model comparison results favored the Exponential-Weight Mean-Variance (EWMV) model, which encompasses and delineates five cognitive components of risk-taking: prior belief, learning rate, risk preference, loss aversion, and behavioral consistency. Both BD groups, regardless of SUD history, showed lower behavioral consistency than HC. BD+ exhibited more pessimistic prior beliefs (relative to BD- and HC) and reduced loss aversion (relative to HC) during risk-taking on the BART. Traditional measures of risk-taking on the BART (adjusted pumps, total points, total pops) detected no group differences. These findings suggest that reduced behavioral consistency is a crucial feature of risky decision-making in BD and that SUD history in BD may signal additional trait vulnerabilities for risky behavior even when mood symptoms and substance use are in remission. This study also underscores the value of using mathematical modeling to understand behavior in research on complex disorders like BD.

Naturalistic smartphone keyboard typing reflects processing speed and executive function

OBJECTIVE

The increase in smartphone usage has enabled the possibility of more accessible ways to conduct neuropsychological evaluations. The objective of this study was to determine the feasibility of using smartphone typing dynamics with mood scores to supplement cognitive assessment through trail making tests.

METHODS

Using a custom-built keyboard, naturalistic keypress dynamics were unobtrusively recorded in individuals with bipolar disorder (n = 11) and nonbipolar controls (n = 8) on an Android smartphone. Keypresses were matched to digital trail making tests part B (dTMT-B) administered daily in two periods and weekly mood assessments. Following comparison of dTMT-Bs to the pencil-and-paper equivalent, longitudinal mixed-effects models were used to analyze daily dTMT-B performance as a function of typing and mood.

RESULTS

Comparison of the first dTMT-B to paper TMT-B showed adequate reliability (intraclass correlations = 0.74). In our model, we observed that participants who typed slower took longer to complete dTMT-B (b = 0.189, p < .001). This trend was also seen in individual fluctuations in typing speed and dTMT-B performance (b = 0.032, p = .004). Moreover, participants who were more depressed completed the dTMT-B slower than less depressed participants (b = 0.189, p < .001). A practice effect was observed for the dTMT-Bs.

CONCLUSION

Typing speed in combination with depression scores has the potential to infer aspects of cognition (visual attention, processing speed, and task switching) in people's natural environment to complement formal in-person neuropsychological assessments that commonly include the trail making test.

Sleep quality and neuropsychological functioning in bipolar I disorder

BACKGROUND

Individuals with bipolar I disorder (BD-I) experience both poor sleep and neuropsychological dysfunction relative to non-psychiatric populations, which limits functional recovery. Poor sleep adversely affects learning, memory, and executive functioning in healthy individuals; however, little is known about the role of poor sleep in neuropsychological functioning in BD-I. We tested whether sleep disturbance was greater in BD-I than healthy control participants (HC), and compared the effect of sleep quality on learning, memory, and executive functioning between BD-I and HC.

METHODS

Participants with BD-I (N=250) and HC (N=206) completed the Pittsburgh Sleep Quality Index, neuropsychological testing, and clinician-administered mood measures as part of a naturalistic study of bipolar disorder. We examined effects of both diagnosis and sleep quality on neuropsychological functioning.

RESULTS

Relative to HC, BD-I showed poorer sleep quality and neuropsychological functioning in verbal learning, verbal and visual memory, processing speed, psychomotor speed, inhibitory control, and selective attention (7/9 domains). Poor sleep quality was associated with poorer verbal learning, verbal fluency, processing speed, and interference control (4/9). Effects of poor sleep on neuropsychological functioning did not differ between BD-I and HC.

LIMITATIONS

The assessment of sleep quality using a self-report measure and the effects of medications/sleeping aids (given the naturalistic study design) should be considered when interpreting results.

CONCLUSIONS

Those with BD-I experiencing poor sleep may also be more vulnerable to verbal learning and executive functioning impairments. The findings of poor sleep in relation to poorer neuropsychological functioning have implications for assessment and treatment of sleep disturbance in BD-I.

Metabolic Syndrome Impairs Executive Function in Bipolar Disorder

Background: Metabolic syndrome (MetS) is more prevalent in individuals with bipolar disorder and has a negative impact on cognition, in particular on executive function, which is already impaired in individuals with bipolar disorder compared to healthy controls.

Methods: In a cross-sectional study, we compared 148 euthymic patients with bipolar disorder and 117 healthy controls in cognitive function depending on the diagnosis of MetS. A neuropsychological test battery was used including the Trail Making Test A/B, Stroop Color and Word Interference Test, the d2 Test of Attention Revised, and the California Verbal Learning Test. In addition, MetS variables as well as the defining variables waist circumference, serum triglyceride levels, high-density lipoprotein cholesterol levels, blood pressure, fasting glucose levels, and body mass index were compared between patients and controls. In addition, illness-related variables were associated with MetS in individuals with bipolar disorder.

Results: The prevalence of MetS in patients with bipolar disorder was higher than in controls (30.4 vs. 15.4%). Patients with bipolar disorder with MetS had impaired executive function compared to patients without MetS or healthy controls with and without MetS (p = 0.020). No MetS effects or interaction MetS × Group was found in attention/processing speed (p = 0.883) and verbal learning/memory (p = 0.373). Clinical variables (illness duration, suicidality, number of affective episodes, medication, age of onset, and history of psychosis) did not relate to MetS in bipolar disorder (p > 0.05).

Conclusion: Bipolar disorder comorbid with MetS bears additional risk for impaired executive function. Executive function includes action planning, inhibition, and impulse control and could play a critical role in keeping long-term goals in mind associated with gaining and maintaining a healthy weight.

Metacognitive knowledge and experience across multiple cognitive domains in euthymic bipolar disorder

Background

Metacognitive knowledge (MK; general awareness of cognitive functioning) and metacognitive experience (ME; awareness of cognitive performance on a specific cognitive task) represent two facets of metacognition that are critical for daily functioning, but are understudied in bipolar disorder. This study was conducted to evaluate MK and ME across multiple cognitive domains in individuals diagnosed with bipolar disorder and unaffected volunteers, and to investigate the association between metacognition and quality of life (QoL).

Methods

Fifty-seven euthymic participants with bipolar disorder and 55 demographically similar unaffected volunteers provided prediction and postdiction ratings of cognitive task performance across multiple cognitive domains. Self-ratings were compared to objective task performance, and indices of MK and ME accuracy were generated and compared between groups. Participants rated QoL on the Quality of Life in Bipolar Disorder Scale (QoL.BD).

Results

Metacognitive inaccuracies in both MK and ME were observed in participants with bipolar disorder, but only in select cognitive domains. Furthermore, most metacognitive inaccuracies involved underestimation of cognitive ability. Metacognitive indices were minimally associated with medication variables and mood symptoms, but several indices were related to QoL.

Conclusions

Individuals with bipolar disorder demonstrate inaccuracies in rating their cognitive functioning and in rating their online cognitive task performance, but only on select cognitive functions. The tendency to underestimate performance may reflect a negative information processing bias characteristic of mood disorders. Metacognitive variables were also predictive of QoL, indicating that further understanding of cognitive self-appraisals in persons with bipolar disorder has significant clinical relevance.

The Effects of Bipolar Disorder Risk on a Mobile Phone Keystroke Dynamics Based Biomarker of Brain Age

Background: Research by our group and others have demonstrated the feasibility of using mobile phone derived metadata to model mood and cognition. Given the effects of age and mood on cognitive performance, it was hypothesized that using such data a model could be built to predict chronological age and that differences between predicted age and actual age could be a marker of pathology. Methods: These data were collected via the ongoing BiAffect study. Participants complete the Mood Disorders Questionnaire (MDQ), a screening questionnaire for bipolar disorder, and self-reported their birth year. Data were split into training and validation sets. Features derived from the smartphone kinematics were used to train random forest regression models to predict age. Prediction errors were compared between participants screening positive and negative on the MDQ. Results: Three hundred forty-four participants had analyzable data of which 227 had positive screens for bipolar disorder and 117 had negative screens. The absolute prediction error tended to be lower for participants with positive screens (median 4.50 years) than those with negative screens (median 7.92 years) (W = 508, p = 0.0049). The raw prediction error tended to be lower for participants with negative screens (median = -5.95 years) than those with positive screens (median = 0.55 years) (W = 1,037, p= 0.037). Conclusions: The tendency to underestimate the chronological age of participants screening negative for bipolar disorder compared to those screening positive is consistent with the finding that bipolar disorder may be associated with brain changes that could reflect pathological aging. This interesting result could also reflect that those who screen negative for bipolar disorder and who engaged in the study were more likely to have higher premorbid functioning. This work demonstrates that age-related changes may be detected via a passive smartphone kinematics based digital biomarker.

A Lifespan Model of Interference Resolution and Inhibitory Control: Risk for Depression and Changes with Illness Progression

The cognitive processes involved in inhibitory control accuracy (IC) and interference resolution speed (IR) or broadly - inhibition - are discussed in this review, and both are described within the context of a lifespan model of mood disorders. Inhibitory control (IC) is a binary outcome (success or no for response selection and inhibition of unwanted responses) for any given event that is influenced to an extent by IR. IR refers to the process of inhibition, which can be manipulated by task design in earlier and later stages through use of distractors and timing, and manipulation of individual differences in response proclivity. We describe the development of these two processes across the lifespan, noting factors that influence this development (e.g., environment, adversity and stress) as well as inherent difficulties in assessing IC/IR prior to adulthood (e.g., cross-informant reports). We use mood disorders as an illustrative example of how this multidimensional construct can be informative to state, trait, vulnerability and neuroprogression of disease. We present aggregated data across numerous studies and methodologies to examine the lifelong development and degradation of this subconstruct of executive function, particularly in mood disorders. We highlight the challenges in identifying and measuring IC/IR in late life, including specificity to complex, comorbid disease processes. Finally, we discuss some potential avenues for treatment and accommodation of these difficulties across the lifespan, including newer treatments using cognitive remediation training and neuromodulation.

Decreased working memory capacity among individuals with a mood disorder who have increased metabolic burden

BACKGROUND

Individuals with mood disorders experience a higher rate of obesity than the general population, putting them at risk for poorer outcomes. The relationship between obesity and a core feature of the mood disorders, neurocognition, is less understood. We examined the interaction of obesity as indexed by body mass index (BMI) and working memory performance in a large sample of individuals with bipolar disorder (BD), major depressive disorder (MDD), and healthy controls (HC).

METHODS

Participants with BD (n = 133), MDD (n = 78), and HC (n = 113) (age range 18-40) completed a spatial working memory (SWM) task that included three-graded increases in the number of target locations. Participants were subdivided by BMI classification into six diagnostic-BMI (BMI groups: Normal Weight, Overweight/Obese) subgroups. Performance on the task was indexed by number of errors within each difficulty level.

RESULTS

The number of errors, across all groups, increased with task difficulty. There was an interaction between errors and diagnostic-BMI group. Post-hoc analyses indicated that while the Normal Weight-BD group did not differ in performance from the other groups, the Overweight/Obese-BD group performed significantly worse than HC groups.

LIMITATIONS

Metabolic effects of psychotropic medications due to the naturalistic nature of the study, younger age of the MDD sample, and utilizing self-reported indicators of obesity may limit generalizability.

CONCLUSIONS

Individuals with BD with increased metabolic burden exhibit increased working memory errors than non-psychiatric controls who also have increased metabolic burden. Future work could address prevention and amelioration of such difficulties to reduce associated functional morbidity.

Genetic Intersections of Language and Neuropsychiatric Conditions

PURPOSE OF REVIEW

To better understand the shared basis of language and mental health, this review examines the behavioral and neurobiological features of aberrant language in five major neuropsychiatric conditions. Special attention is paid to genes implicated in both language and neuropsychiatric disorders, as they reveal biological domains likely to underpin the processes controlling both.

RECENT FINDINGS

Abnormal language and communication are common manifestations of neuropsychiatric conditions, and children with impaired language are more likely to develop psychiatric disorders than their peers. Major themes in the genetics of both language and psychiatry include master transcriptional regulators, like FOXP2; key developmental regulators, like AUTS2; and mediators of neurotransmission, like GRIN2A and CACNA1C.

Cluster analysis with MOODS-SR illustrates a potential bipolar disorder risk phenotype in young adults with remitted major depressive disorder

OBJECTIVES

Delays in the diagnosis and detection of bipolar disorder can lead to adverse consequences, including improper treatment and increased suicide risk. The Mood Spectrum Self-Report Measure (MOODS-SR) was designed to capture the full spectrum of lifetime mood symptomology with factor scores for depression and mania symptom constellations. The utility of the MOODS-SR as a tool to investigate homogeneous subgroups was examined, with particular focus on a possible bipolar risk subgroup. Moreover, potential patterns of differences in MOODS-SR subtypes were probed using cognitive vulnerabilities, neuropsychological functioning, and ventral striatum connectivity.

METHODS

K-mean cluster analysis based on factor scores of MOODS-SR was used to determine homogeneous subgroupings within a healthy and remitted depressed young adult sample (N = 86). Between-group comparisons (based on cluster subgroupings) were conducted on measures of cognitive vulnerabilities, neuropsychological functioning, and ventral striatum rs-fMRI connectivity.

RESULTS

Three groups of participants were identified: one with minimal symptomology, one with moderate primarily depressive symptomology, and one with more severe manic and depressive symptomology. Differences in impulsivity, neuroticism, conscientiousness, facial perception accuracy, and rs-fMRI connectivity exist between moderate and severe groups.

CONCLUSIONS

Within a sample of people with and without depression histories, a severe subgroup was identified with potentially increased risk of developing bipolar disorder through use of the MOODS-SR. This small subgroup had higher levels of lifetime depression and mania symptoms. Additionally, differences in traits, affective processing, and connectivity exist between those with a more prototypic unipolar subgrouping and those with potential risk for developing bipolar disorder.

Predicting Mood Disturbance Severity with Mobile Phone Keystroke Metadata: A BiAffect Digital Phenotyping Study

Background

Mood disorders are common and associated with significant morbidity and mortality. Better tools are needed for their diagnosis and treatment. Deeper phenotypic understanding of these disorders is integral to the development of such tools. This study is the first effort to use passively collected mobile phone keyboard activity to build deep digital phenotypes of depression and mania.

Objective

The objective of our study was to investigate the relationship between mobile phone keyboard activity and mood disturbance in subjects with bipolar disorders and to demonstrate the feasibility of using passively collected mobile phone keyboard metadata features to predict manic and depressive signs and symptoms as measured via clinician-administered rating scales.

Methods

Using a within-subject design of 8 weeks, subjects were provided a mobile phone loaded with a customized keyboard that passively collected keystroke metadata. Subjects were administered the Hamilton Depression Rating Scale (HDRS) and Young Mania Rating Scale (YMRS) weekly. Linear mixed-effects models were created to predict HDRS and YMRS scores. The total number of keystrokes was 626,641, with a weekly average of 9791 (7861), and that of accelerometer readings was 6,660,890, with a weekly average 104,076 (68,912).

Results

A statistically significant mixed-effects regression model for the prediction of HDRS-17 item scores was created: conditional R²=.63, P=.01. A mixed-effects regression model for YMRS scores showed the variance accounted for by random effect was zero, and so an ordinary least squares linear regression model was created: R²=.34, P=.001. Multiple significant variables were demonstrated for each measure.

Conclusions

Mood states in bipolar disorder appear to correlate with specific changes in mobile phone usage. The creation of these models provides evidence for the feasibility of using passively collected keyboard metadata to detect and monitor mood disturbances.

Developing Dimensional, Pandiagnostic Inhibitory Control Constructs With Self-Report and Neuropsychological Data

Trait markers, or intermediate phenotypes linking different units of analysis (self-report, performance) from the Research Domain Criteria (RDoC) matrix across populations is a necessary step in identifying at-risk individuals. In the current study, 150 healthy controls (HC) and 456 individuals with bipolar disorder (BD) Type I or II, NOS (not otherwise specified) or Schizoaffective BD completed self-report neuropsychological tests of inhibitory control (IC) and executive functioning. Bifactor analyses were used to examine the factor structure of these measures and to evaluate for invariance across groups. Bifactor analyses found modest convergence of items from neuropsychological tests and self-report measures of IC among HC and BD. The factor scores showed evidence of a general IC construct (i.e., subdomain) across measures. Importantly, invariance testing indicated that the same construct was measured equally well across groups. Groups differed on the general factor for three of the four scales. Convergence on a general IC factor and invariance across diagnosis supports the use of combined dimensional measures to identify clinical risk and highlights how prospective RDoC studies might integrate units of analysis.

Psychosis in bipolar disorder: Does it represent a more "severe" illness?

OBJECTIVES

Although there is a common clinical assumption that bipolar disorder with psychotic features reflects greater severity than bipolar disorder without psychosis, the existing empirical literature is mixed. This study investigated the phenomenology of psychosis as well as demographic, clinical, functional, and neuropsychological features in a large, cross-sectional sample of participants with bipolar disorder divided by history of psychosis.

METHODS

In a large single study, 168 affective-only bipolar disorder (BP-A) participants and 213 bipolar disorder with a history of psychosis (BP-P) participants completed a comprehensive clinical diagnostic interview and neuropsychological testing. t tests, chi-square tests, and Bayes factors were used to investigate group differences or lack thereof.

RESULTS

The prevalence of psychosis in this sample (53%) was similar to published reports. Nearly half of BP-P participants experienced grandiose delusions, and relatively few endorsed "first-rank" hallucinations of running commentary or two or more voices conversing. There were no demographic or neuropsychological differences between groups. BP-A participants experienced greater chronicity of affective symptoms and a greater degree of rapid cycling than BP-P participants; there were no other clinical differences between groups.

CONCLUSIONS

Overall, these results contradict the conventional notion that bipolar disorder with psychotic features represents a more severe illness than bipolar disorder without a history of psychosis. The presence of psychosis does not appear to be associated with poorer clinical/functional outcome or suggest a greater degree of neuropsychological impairment; conversely, the absence of psychosis was associated with affective chronicity and rapid cycling. Nosological and treatment implications are discussed.

Biochemical abnormalities in basal ganglia and executive dysfunction in acute- and euthymic-episode patients with bipolar disorder: A proton magnetic resonance spectroscopy study

BACKGROUND

Recent studies found abnormal biochemical metabolism and executive cognitive deficits in acute bipolar disorder (BD). However, the evidence concerning in euthymic BD is limited. Thus, a comparison between acute and euthymic BD is conductive to better understanding the association between cognition and the outcome of neuroimaging. This study sought to investigate the relationship between the executive function and the biochemical metabolism in acute- and euthymic-episode BD patients and delineate the prominent endophenotype of BD.

METHODS

Three groups of participants were recruited in this study: 30 BD patients with an acute depressive episode, 22 euthymic BD patients, and 31 healthy controls. All participants were interviewed using the Structured Clinical Interview for DSM-IV, and underwent two-dimensional multivoxel proton magnetic resonance spectroscopy (1H-MRS) to obtain the bilateral metabolite levels in the lenticular nucleus of basal ganglia(BG). The ratios of N-acetylaspartate (NAA)/creatine (Cr) and Choline-containing compounds (Cho) /Cr ratios were calculated. Executive function was assessed by using the Wisconsin Card Sorting Test (WCST) and Trail Making Test, Part-B(TMT-B).

RESULTS

The comparison of biochemical changes showed that the NAA/Cr ratios in bilateral lenticular nucleus in both acute and euthymic BD patients was significantly lower than that in healthy controls at a confidence level of p<0.05. In the comparison of executive function, both acute and euthymic BD patients showed significantly decreased numbers of categories completed, and increased numbers of total errors, perseverative and noperseverative errors, and TMT-B uptake compared to the healthy controls at a confidence level of p<0.05. There were no significant differences between the acute BD and euthymic BD groups in the biochemical metabolite ratios and executive function. We found that the NAA/Cr ratio in the left in BG in the acute -episode BD patients was positively correlated with the number of categories completed, whereas it was negatively correlated with the total errors and TMT-B uptake. There was no correlation between the NAA/Cr and Cho/Cr ratios in the bilateral BG and the scores of SWCT and TMT-B in euthymic-episode BD patients.

LIMITATION

The sample size was relatively small and not all the euthymic-episode patients are the ones with an acute episode.

CONCLUSIONS

Our findings suggest that biochemical abnormalities in the lenticular nucleus and the executive dysfunction may occur early in the course of BD, and persist during remission, and are the most likely markers of endophenotypes of BD. The dysfunction of the neuronal function in the lenticular nucleus may be correlated with the cold dysfunction in patients with acute BD.

Equivalent linear change in cognition between individuals with bipolar disorder and healthy controls over 5 years

OBJECTIVES

Cognitive dysfunction is a key feature of bipolar disorder (BD). However, not much is known about its temporal stability, as some studies have demonstrated a neurodegenerative model in BD while others have shown no change in cognitive functioning over time. Building upon our prior work, which examined the natural course of executive functioning, the current study aimed to investigate the natural course of memory, emotion processing, and fine motor dexterity over a 5-year period in BD and healthy control (HC) samples.

METHODS

Using a 5-year longitudinal cohort, 90 individuals with BD and 17 HCs were administered a battery of neuropsychological tests at study baseline and at 1 and 5 years after study entry that captured four areas of cognitive performance: visual memory, auditory memory, emotion processing, and fine motor dexterity.

RESULTS

Latent growth curve modeling showed no group differences in the slopes of any of the cognitive factors between the BD and HC groups. Age at baseline was negatively associated with visual memory, emotion processing, and fine motor dexterity. Education level was positively associated with auditory and visual memory and fine motor. Female gender was negatively associated with emotion processing.

CONCLUSIONS

Extending our prior work on longitudinal evaluation of executive functioning, individuals with BD show similar linear change in other areas of cognitive functioning including memory, emotion processing, and fine motor dexterity as compared to unaffected HCs. Age, education, and gender may have some differential effects on cognitive changes.

Domain-specific impairment in cognitive control among remitted youth with a history of major depression

AIM

Impairment in neuropsychological functioning is common in major depressive disorder (MDD), but it is not clear to what degree these deficits are related to risk (e.g. trait), scar, burden or state effects of MDD. The objective of this study was to use neuropsychological measures, with factor scores in verbal fluency, processing speed, attention, set-shifting and cognitive control in a unique population of young, remitted, unmedicated, early course individuals with a history of MDD in hopes of identifying putative trait markers of MDD.

METHODS

Youth aged 18-23 in remission from MDD (rMDD; n = 62) and healthy controls (HC; n = 43) were assessed with neuropsychological tests at two time points. These were from four domains of executive functioning, consistent with previous literature as impaired in MDD: verbal fluency and processing speed, conceptual reasoning and set-shifting, processing speed with interference resolution, and cognitive control.

RESULTS

rMDD youth performed comparably to HCs on verbal fluency and processing speed, processing speed with interference resolution, and conceptual reasoning and set-shifting, reliably over time. Individuals with rMDD demonstrated relative decrements in cognitive control at Time 1, with greater stability than HC participants.

CONCLUSION

MDD may be characterized by regulatory difficulties that do not pertain specifically to active mood state or fluctuations in symptoms. Deficient cognitive control may represent a trait vulnerability or early course scar of MDD that may prove a viable target for secondary prevention or early remediation.

Executive functioning deficits among adults with Bipolar Disorder (types I and II): A systematic review and meta-analysis

BACKGROUND

Executive functioning (EF) deficits contribute to a significant proportion of the burden of disease associated with bipolar disorder (BD). Yet, there is still debate in the literature regarding the exact profile of executive functioning in BD. The purpose of the present project was to assess whether EF deficits exist among adults suffering BD, and whether these deficits (if apparent) differ by BD subtype.

METHODS

A systematic search identified relevant literature. Randomised controlled trials that used neuropsychological assessment to investigate EF among adults 16-65 years) with a remitted DSM diagnosis of BD (type I or II) were included. Studies were published between 1994 and 2015. A systematic review and meta-analysis were undertaken. For individual studies, standardised mean differences (Cohen's d) and 95% confidence intervals were calculated and represented in forest plots to illustrate differences in executive performance between groups. Summary effects were produced and tests of heterogeneity employed to assess the dispersion and generalisability of results.

RESULTS

Thirty-six studies met criteria for inclusion. Six domains of EF were identified: Set-shifting (SS), inhibition (INH), planning (PLA), verbal fluency (VF), working memory (WM), and attention (ATT). BD1s performed worse than HCs in all domains. BD2s demonstrated impairment in VF, WM, SS, and ATT. The results were mixed for comparisons between BD1s and BD2s, but revealed that BD2s can experience similar (or sometimes greater) EF impairment.

LIMITATIONS

Only a limited number of studies that included BD2 samples were available for inclusion in the current study. Subgroup analysis to elucidate potential moderators of within-study variance was not undertaken.

CONCLUSION

This is the first systematic review and meta-analysis to have compared the EF of remitted BD1s, BD2s, and HCs. The results provided useful insight into the EF profile of patients with BD, and offered commentary as to some of the contradictory results reported in the literature. A standardised methodological protocol for assessment of EF in BD was proposed. The information in this review could enhance our understanding of EF impairment inherent in BD, and the methods and efficacy with which clinicians assess and treat this population.

Response inhibition in the parametric Go/No-Go task in psychopathic offenders

Previous research on response inhibition in psychopaths has failed to find consistent evidence for aberrant inhibitory ability, despite strong expectations to the contrary. However, previous examinations have utilised inhibition paradigms that suffer from critical shortcomings, such as a lack of ecological validity and overly simplistic response criteria. To assess inhibition under conditions close to the demands of everyday settings, the current study employs a parametric Go/No-go task in male offenders (n77). Additionally, rather than treating psychopathy as a categorical descriptor, a dimensional approach is taken to assess the relationship between individual psychopathic traits and response inhibition performance. Results indicate significant relationships between response inhibition and individual facets of psychopathy as measured by the Psychopathy Checklist: Screening Version. A positive relationship was found between inhibitory ability and interpersonal aspects of psychopathy, reflecting an enhancement of inhibitory functioning for those scoring high on this facet. In addition, a negative association was found between psychopathic lifestyle characteristics and response inhibition. Whereas the negative association mirrors the conceptualisation of the lifestyle facet, the positive association between interpersonal psychopathic aspects and response inhibition might reflect a propensity for adaptive behaviour that enables psychopaths to adequately manipulate their victims and mask their true nature.

Cognitive inconsistency in bipolar patients is determined by increased intra-individual variability in initial phase of task performance

BACKGROUND

Bipolar patients show high intra-individual variability during cognitive processing. However, it is not known whether there are a specific fluctuations of variability contributing to the overall high cognitive inconsistency. The objective was to compare dynamic profiles of patients and healthy controls to identify hypothetical differences and their associations with overall variability and processing speed.

METHODS

Changes of reaction times iSD during processing speed test performance over time was measured by dividing the iSD for whole task into four consecutive parts. Motor speed and cognitive effort were controlled.

RESULTS

Patients with BD exhibited significantly lower results regarding processing speed and higher intra-individual variability comparing with HC. The profile of intra-individual variability changes over time of performance was significantly different in BD versus HC groups: F(3, 207)=8.60, p<0.0001, η_p²=0.11. iSD of BD patients in the initial phase of performance was three times higher than in the last. There was no significant differences between four intervals in HC group. Inter-group difference in the initial part of the profiles was significant also after controlling for several cognitive and clinical variables.

LIMITATIONS

Applied computer version of Cognitive Speed Test was relatively new and, thus, replication studies are needed. Effect seen in the present study is driven mainly by the BD type I.

CONCLUSIONS

Patients with BD exhibits problems with setting a stimulus-response association in starting phase of cognitive processing. This deficit may negatively interfere with the other cognitive functions, decreasing level of psychosocial functioning, therefore should be explored in future studies.

Influence of cognitive reserve on neuropsychological functioning in bipolar disorder: Findings from a 5-year longitudinal study

OBJECTIVES

The present study examined the 5-year longitudinal course of cognitive functioning in a large sample of well-characterized patients with bipolar disorder (BP), compared to healthy controls (HCs), and the influence of cognitive reserve factors (e.g., education and IQ) on cognitive change over time.

METHODS

Participants included 159 individuals diagnosed with BP and 54 HCs recruited as part of a longitudinal naturalistic study of BP who had completed neuropsychological testing at the time of their enrollment and again 5 years later.

RESULTS

The overall relative rate of change did not differ between the BP and HC groups. In total, 46.5% of the BP group and 37% of the HC group showed evidence of decline on at least one measure over time. T-test analyses did not find differences between BP 'decliners' and 'non-decliners' in cognitive reserve variables. However, we found that higher baseline intellectual ability was associated with more stability in cognitive test scores over time for the BP group. Results of linear regression modeling revealed that lower verbal IQ and education were related to increased cognitive decline in specific domains in the BP group.

CONCLUSIONS

This study has explored the influence of cognitive reserve on preservation of specific cognitive abilities over time in BP. The BP group did not demonstrate accelerated cognitive decline over 5 years compared to the HC group. Although the trajectory of cognitive change over time was similar between BP patients and HCs, higher overall intellectual ability may be a protective factor against cognitive decline, particularly for BP patients.

Verbal fluency in bipolar disorders: A systematic review and meta-analysis

BACKGROUND

One of the main features of bipolar disorder (BD), besides mood dysregulation, is an alteration of the structure of language. Bipolar patients present changes in semantic contents, impaired verbal associations, abnormal prosody and abnormal speed of language highlighted with various experimental tasks. Verbal fluency tasks are widely used to assess the abilities of bipolar patients to retrieve and produce verbal material from the lexico-semantic memory. Studies using these tasks have however yielded discrepant results. The aim of this study was thus to determine the extent of the verbal fluency impairment in BD patients and to evaluate if the deficits are affected by the type of task or by mood states.

METHODS

A systematic literature search was conducted in MEDLINE, EBSCOHost and Google Scholar and relevant data were submitted to a meta-analysis.

RESULTS

Thirty-nine studies were retained providing data for 52 independent groups of BD patients. The overall meta-analysis revealed a moderate verbal fluency impairment in BD compared to healthy controls (effect size d=0.61). Comparisons between mood states showed significant differences only between euthymic and manic patients and only on category fluency performances.

LIMITATIONS

This review is limited by the heterogeneity between studies for the characteristics of BD populations. Also, few of the retained studies examined depressive or mixed episodes.

CONCLUSIONS

This work confirms that BD patients present with moderate verbal fluency impairments, and underlines the specific effect of mood state on category fluency. This emphasizes the need to distinguish semantic from phonological processes in verbal fluency assessments in BD.

Distinct and Shared Endophenotypes of Neural Substrates in Bipolar and Major Depressive Disorders

Little is known about disorder-specific biomarkers of bipolar disorder (BD) and major depressive disorder (MDD). Our aim was to determine a neural substrate that could be used to distinguish BD from MDD. Our study included a BD group (10 patients with BD, 10 first-degree relatives (FDRs) of individuals with BD), MDD group (17 patients with MDD, 17 FDRs of individuals with MDD), and 27 healthy individuals. Structural and functional brain abnormalities were evaluated by voxel-based morphometry and a trail making test (TMT), respectively. The BD group showed a significant main effect of diagnosis in the gray matter (GM) volume of the anterior cingulate cortex (ACC; p = 0.01) and left insula (p < 0.01). FDRs of individuals with BD showed significantly smaller left ACC GM volume than healthy subjects (p < 0.01), and patients with BD showed significantly smaller ACC (p < 0.01) and left insular GM volume (p < 0.01) than healthy subjects. The MDD group showed a tendency toward a main effect of diagnosis in the right and left insular GM volume. The BD group showed a significantly inverse correlation between the left insular GM volume and TMT-A scores (p < 0.05). Our results suggest that the ACC volume could be a distinct endophenotype of BD, while the insular volume could be a shared BD and MDD endophenotype. Moreover, the insula could be associated with cognitive decline and poor outcome in BD.

Reconsidering Dietary Polyunsaturated Fatty Acids in Bipolar Disorder: A Translational Picture

Inflammation is an important mediator of pathophysiology in bipolar disorder. The omega-3 (n-3) and omega-6 (n-6) polyunsaturated fatty acid (PUFA) metabolic pathways participate in several inflammatory processes and have been linked through epidemiologic and clinical studies to bipolar disorder and its response to treatment. We review the proposed role of PUFA metabolism in neuroinflammation, modulation of brain PUFA metabolism by antimanic medications in rodent models, and anti-inflammatory pharmacotherapy in bipolar disorder and in major depressive disorder (MDD). Although the convergence of findings between preclinical and postmortem clinical data is compelling, we investigate why human trials of PUFA as treatment are mixed. We view the biomarker and treatment study findings in light of the evidence for the hypothesis that arachidonic acid hypermetabolism contributes to bipolar disorder pathophysiology and propose that a combined high n-3 plus low n-6 diet should be tested as an adjunct to current medication in future trials.

Similar Trajectory of Executive Functioning Performance over 5 years among individuals with Bipolar Disorder and Unaffected Controls using Latent Growth Modeling

OBJECTIVE

Executive Functioning (EF) deficits in bipolar disorder (BD) are commonly present regardless of mood state and therefore are considered core features of the illness. However, very little is known about the temporal stability of these deficits. We examined the natural course of EF over a five year period in BD and healthy control (HC) samples.

METHOD

Using a 5-year longitudinal cohort, 91 individuals with BD and 17 HC were administered a battery of neuropsychological tests that captured four main areas of EF: Processing Speed with Interference Resolution, Verbal Fluency with Processing Speed, Inhibitory Control, and Conceptual Reasoning and Set Shifting. Evaluations occurred at study entry, one, and five years later.

RESULTS

Latent Growth Curve Modeling demonstrated that the BD group performed significantly worse in all EF areas than the HC group. Changes in EF from baseline to 5-year follow-up were similar across both diagnostic groups. Older age at baseline, above and beyond education and diagnosis, was associated with worse initial performance in EF. Being of older age was associated with greater decline in Processing Speed with Interference Resolution, and Verbal Fluency with Processing Speed. Higher education was marginally associated with a smaller declining slope for Processing Speed with Interference Resolution.

CONCLUSIONS

Executive functioning deficits in BD persist over time, and in the context of normative age-related decline, may place individuals at greater risk for cognitive disability as the disease progresses. Age and having a BD diagnosis together, however, do not accelerate executive functioning decline over time.

Cognitive deficits in first-degree relatives of bipolar patients: the use of homogeneous subgroups in the search of cognitive endophenotypes

Previous studies have demonstrated impairments in attention, memory and executive functions in euthymic bipolar patients (BP) as well as their unaffected first-degree relatives, albeit in an attenuated form. Subsequently, cognitive deficits are discussed as a possible endophenotype of bipolar disorder. However, recent studies showed that only a subgroup of BP shows cognitive impairments. The aim of the present study was to investigate cognitive functioning in relatives compared to BP, to find out if the differentiation in a cognitive deficit vs. non-deficit subgroup is valid for relatives of BP, too. Therefore, the performance of 27 unaffected relatives of BP, 27 euthymic BP and 27 HC were compared using a neuropsychological test battery. The results showed that BP exhibited a reduced psychomotor speed and deficits in working memory compared to relatives and HC. Relatives performed significantly slower (psychomotor speed) as compared to HC (p = 0.024); performance in the other test measures lie between BP and HC. Furthermore, a detailed evaluation of the data indicated that only subgroups of BP and relatives exhibited cognitive impairments in the implemented tests. However, the deficit and non-deficit groups did not differ in sociodemographic and clinical variables from each other, possibly due to the small sample size. In conclusion, our results suggest that reduced psychomotor speed could serve as a potential endophenotype for bipolar disorder which should be investigated along the developmental trajectory of this disorder, also to examine whether abnormalities therein precede onset of the first mood episode. Furthermore, the division of relatives into subgroups aids in the identification of stable trait markers and high-risk bipolar groups and could enable early prevention strategies. As to that more research using distinct and homogeneous subgroups is necessary.

The manic phase of Bipolar disorder significantly impairs theory of mind decoding

Bipolar disorder is associated with significant deficits in the decoding of others' mental states in comparison to healthy participants. However, differences in theory of mind decoding ability among patients in manic, depressed, and euthymic phases of bipolar disorder is currently unknown. Fifty-nine patients with bipolar I or II disorder (13 manic, 25 depressed, 20 euthymic) completed the "Reading the Mind in the Eyes" Task (Eyes task) and the Animals Task developed to control for non-mentalistic response demands of the Eyes Task. Patients also completed self-report and clinician-rated measures of depression, mania, and anxiety symptoms. Patients in the manic phase were significantly less accurate than those in the depressed and euthymic phases at decoding mental states in the Eyes task, and this effect was strongest for eyes of a positive or neutral valence. Further Eyes task performance was negatively correlated with the symptoms of language/thought disorder, pressured speech, and disorganized thoughts and appearance. These effects held when controlling for accuracy on the Animals task, response times, and relevant demographic and clinical covariates. Results suggest that the state of mania, and particularly psychotic symptoms that may overlap with the schizophrenia spectrum, are most strongly related to social cognitive deficits in bipolar disorder.

The double burden of age and major depressive disorder on the cognitive control network

Poor cognitive control (CC) is common among older individuals with major depressive disorder (OMDD). At the same time, studies of CC in OMDD with fMRI are relatively limited and often have small samples. The present study was conducted to further examine poor CC in OMDD with early onset depression, as well as to investigate the interactive effects of MDD and aging on cognitive control. Twenty OMDD, 17 older never-depressed comparisons (ONDC), 16 younger adults with MDD (YMDD), and 18 younger never-depressed comparisons (YNDC) participated. All participants completed the Go level of the Parametric Go/No-Go Test, which requires sustained attention and inhibitory control while undergoing functional MRI (fMRI). YNDC were faster in reaction times (RTs) to go targets relative to the other 3 groups, and the YMDD group was faster than the OMDD group. fMRI effects of both age and diagnosis were present, with greater activation in MDD, and in aging. Additionally, the interaction of age and MDD was also significant, such that OMDD exhibited greater recruitment of fronto-subcortical regions relative to older comparisons. These results are consistent with prior research reporting that OMDD recruit more fronto-striatal regions in order to perform at the same level as their never-depressed peers, here on a task of sustained attention and inhibitory control. There may be an interaction of cognitive aging and depression to create a double burden on the CC network in OMDD, including possible fronto-striatal compensation during CC that is unique to OMDD, as younger MDD individuals do not show this pattern.

Patients with bipolar disorder show differential executive dysfunctions: A case-control study

Executive deficits in euthymic bipolar I disorder were examined in a fractionated manner based on the "Supervisory Attentional System" (SAS) model, and the relationship between the degree of executive impairment and the demographic and clinical characteristics of bipolar I participants was explored. A battery of neurocognitive tests capturing specific components of executive function was administered on 30 patients with bipolar I disorder in euthymic state, and compared with 30 healthy controls who were matched by age, gender and IQ. A differential impairment in executive function was demonstrated in euthymic bipolar I participants by using a fractionated approach of the SAS. Euthymic bipolar I patients were found to have significantly poorer performance in immediate and delayed visual memory; and in the executive domains of "initiation", "sustained attention", and "attention allocation and planning". Those with a greater number of executive impairments had lower IQ and higher negative sub-scores on PANSS. These findings might provide a the basis for further studies on identifying the executive components that are associated with particular disease characteristics of bipolar disorder, and those with poorer functional outcome, so that rehabilitation can be focused on the selective domains concerned.

Interaction between COMT rs5993883 and second generation antipsychotics is linked to decreases in verbal cognition and cognitive control in bipolar disorder

BACKGROUND

Second generation antipsychotics (SGAs) are increasingly utilized in Bipolar Disorder (BD) but are potentially associated with cognitive side effects. Also linked to cognitive deficits associated with SGA-treatment are catechol-O-methyltransferase (COMT) gene variants. In this study, we examine the relationship between cognition in SGA use and COMT rs5993883 in cohort sample of subjects with BD.

METHODS

Interactions between SGA-treatment and COMT rs5993883 genotype on cognition was tested using a battery of neuropsychological tests performed in cross-sectional study of 246 bipolar subjects.

RESULTS

The mean age of our sample was 40.15 years and was comprised of 70 % female subjects. Significant demographic differences included gender, hospitalizations, benzodiazepine/antidepressant use and BD-type diagnosis. Linear regressions showed that the COMT rs5993883 GG genotype predicted lower verbal learning (p = 0.0006) and memory (p = 0.0026) scores, and lower scores on a cognitive control task (p = 0.004) in SGA-treated subjects. Interestingly, COMT GT- or TT-variants showed no intergroup cognitive differences. Further analysis revealed an interaction between SGA-COMT GG-genotype for verbal learning (p = 0.028), verbal memory (p = 0.026) and cognitive control (p = 0.0005).

CONCLUSIONS

This investigation contributes to previous work demonstrating links between cognition, SGA-treatment and COMT rs5993883 in BD subjects. Our analysis shows significant associations between cognitive domains such as verbal-cognition and cognitive control in SGA-treated subjects carrying the COMT rs5993883 GG-genotype. Prospective studies are needed to evaluate the clinical significance of these findings.

Cognitive deficits in bipolar disorder: from acute episode to remission

Considerable evidence demonstrates that neuropsychological deficits are prevalent in bipolar disorder during both acute episodes and euthymia. However, it is less clear whether these cognitive disturbances are state- or trait-related. We here present the first longitudinal study employing a within-subject pre- and post-testing examining acutely admitted bipolar patients (BP) in depression or mania and during euthymia, aiming to identify cognitive performance from acute illness to remission. Cognitive performance was measured during acute episodes and repeated after at least 3 months of remission. To do so, 55 BP (35 depressed, 20 hypo-/manic) and 55 healthy controls (HC) were tested with a neuropsychological test battery (attention, working memory, verbal memory, executive functioning). The results showed global impairments in acutely ill BP compared to HC: depressed patients showed a characteristic psychomotor slowing, while manic patients had severe deficits in executive functioning. Twenty-nine remitted BP could be measured in the follow-up (dropout rate 48 %), whose cognitive functions partially recovered, whereas working memory and verbal memory were still impaired. However, we found that subthreshold depressive symptoms and persisting sleep disturbances in euthymic BP were associated with reduced speed, deficits in attention and verbal memory, while working memory was correlated with psychotic symptoms (lifetime). This result indicates working memory as trait related for a subgroup of BP with psychotic symptoms. In contrast, attention and verbal memory are negatively influenced by state factors like residual symptoms, which should be more considered as possible confounders in the search of cognitive endophenotypes in remitted BP.

Response inhibition in the parametric go/no-go task and its relation to impulsivity and subclinical psychopathy

The current study utilizes the parametric go/no-go task (PGNG), a task that examines changes in inhibitory performance as executive function load increases, to examine the link between psychopathic traits, impulsivity, and response inhibition in a cohort of healthy participants. The results show that as executive function load increased, inhibitory ability decreased. High scores on the Cognitive Complexity subscale of the Barratt Impulsivity Scale (BIS-11) predict poor inhibitory ability in the PGNG. Similarly, high scores on the Psychopathy Personality Inventory-Revised (PPI-R) Blame Externalization subscale predict response inhibition deficits in the PGNG, which loads more on the executive functions than the standard go/no-go task. The remaining BIS-11 as well as PPI-R subscales did not interact with inhibitory performance in the PGNG highlighting the specificity of associations between aspects of personality and impulsivity with inhibitory performance as cognitive load is increased. These data point towards the sensitivity of the PGNG in studying response inhibition in the context of highly impulsive populations and its utility as a measure of impulsivity.

Neuroprogression and Cognitive Functioning in Bipolar Disorder: A Systematic Review

Bipolar disorder (BD) has been associated with impairments in a range of cognitive domains including attention, verbal learning, and mental flexibility. These deficits are increased during the acute phases of the illness and worsen over the course of BD. This review will examine the literature in relation to potential mechanisms associated with cognitive decline in BD. Scopus (all databases), Pubmed, and Ovid Medline were systematically searched with no language or year restrictions, up to January 2015, for human studies that collected cross-sectional and longitudinal cognitive data in adults with BD and matched healthy controls (HC). Selected search terms were "bipolar," "cognitive," "aging," "illness duration," "onset," and "progression." Thirty-nine studies satisfied the criteria for consideration. There is evidence that cognitive function in BD is negatively associated with features of illness progression such as number of mood episodes, illness duration, and hospitalizations. Aging does not appear to affect cognitive functioning to a greater extent than in HC. Furthermore, the small number of longitudinal studies in this field does not allow to reaching firm conclusion in terms of which sub-populations would be more prone to cognitive decline in BD. The decline in cognitive abilities over the course of the BD seems to be associated with the number of episodes and number of hospitalizations. No meaningful interaction of age and bipolar disorder has been found in terms of cognitive decline. Future large-scale longitudinal studies are necessary to confirm these findings and assist in the development of preventive interventions in vulnerable individuals.

Shared dimensions of performance and activation dysfunction in cognitive control in females with mood disorders

Major depressive disorder and bipolar disorder share symptoms that may reflect core mood disorder features. This has led to the pursuit of intermediate phenotypes and a dimensional approach to understand neurobiological disruptions in mood disorders. Executive dysfunction, including cognitive control, may represent a promising intermediate phenotype across major depressive disorder and bipolar disorder. This study examined dimensions of cognitive control in women with major depressive disorder or bipolar disorder in comparison to healthy control subjects using two separate, consecutive experiments. For Experiment 1, participants completed a behavioural cognitive control task (healthy controls = 150, major depressive disorder = 260, bipolar disorder = 202; age range 17-84 years). A sample of those participants (healthy controls = 17, major depressive disorder = 19, and bipolar disorder = 16) completed a similar cognitive control task in an event-related design functional magnetic resonance imaging protocol for Experiment 2. Results for Experiment 1 showed greater impairments on the cognitive control task in patients with mood disorders relative to healthy controls (P < 0.001), with more of those in the mood disorder group falling into the 'impaired' range when using clinical cut-offs (<5th percentile). Experiment 2 revealed only a few areas of shared activation differences in mood disorder greater than healthy controls. Activation analyses using performance as a regressor, irrespective of diagnosis, revealed within and extra-network areas that were more active in poor performers. In summary, performance and activation during cognitive control tasks may represent an intermediate phenotype for mood disorders. However, cognitive control dysfunction is not uniform across women with mood disorders, and activation is linked to performance more so than disease. These findings support subtype and dimensional approaches to understanding risk and expression of mood disorders and are a promising area of inquiry, in line with the Research Domain Criteria initiative of NIMH.

Dorsolateral prefrontal hemodynamic responses during a verbal fluency task in hypomanic bipolar disorder

OBJECTIVES

Neuroimaging studies have suggested prefrontal dysfunction in response to cognitive activation in bipolar disorder (BD). However, its characteristics in manic states have not been well understood. Thus, we compared prefrontal hemodynamic responses during a cognitive task between hypomanic and depressive states in BD. We then longitudinally compared hypomanic and subsequent euthymic states.

METHODS

The prefrontal function of 27 patients with BD (11 hypomanic and 16 depressed) and 12 age- and gender-matched healthy controls (HCs) was evaluated using near-infrared spectroscopy (NIRS) during a verbal fluency task (VFT). Hypomanic symptoms were assessed using the Young Mania Rating Scale. Among the 11 hypomanic patients, eight participated in the second NIRS measurement after their hypomanic symptoms resolved.

RESULTS

VFT performance did not differ among hypomanic, depressed, and HC groups. Both BD groups exhibited significantly lower activation during the VFT than HCs in the broader bilateral prefrontal cortex. Hemodynamic changes in the left dorsolateral prefrontal cortex (DLPFC) in the hypomanic patients with BD were significantly larger than those in the depressed patients. In addition, hypomanic symptom severity was positively correlated with activation in the left DLPFC and frontopolar cortex in patients with BD. Follow-up measurement of the hypomanic patients revealed that prefrontal activation was decreased after hypomanic symptoms resolved.

CONCLUSIONS

Combining cross-sectional and longitudinal assessments, the present results suggest that prefrontal hemodynamic responses associated with cognitive activation differ between hypomanic and depressive states in BD. NIRS measurement could be a useful tool for objectively evaluating state-dependent characteristics of prefrontal hemodynamics in BD.

Reduced white matter integrity and verbal fluency impairment in young adults with bipolar disorder: a diffusion tensor imaging study

BACKGROUND

Clinical evidence shows that bipolar disorder (BD) is characterized by white matter (WM) microstructural abnormalities. However, little is known about the biological mechanisms associated with these abnormalities and their relationship with cognitive functioning.

METHODS

49 adult BD patients ((M±SD): 29.27 ± 7.92 years; 17 males, 32 females; 34 BD-I, 10 BD-II, and 5 BD-NOS) and 28 age-matched normal subjects ((M±SD): 29.19 ± 7.35 years; 10 males and 18 females) underwent diffusion tensor imaging (DTI) imaging. DTI metrics were computed using whole-brain tract-based spatial statistics (TBSS) as part of the FMRIB Software Library. Measures of WM coherence (fractional anisotropy - FA) and axonal structure (mean, axial and radial diffusivity - MD, AD and RD) were employed to characterize the microstructural alterations in the limbic, commissural, association and projection fiber tracts. All participants performed the Brief Assessment of Cognition for Affective disorders (BAC-A).

RESULTS

BD patients performed poorly on verbal fluency tasks and exhibited large clusters of altered FA, RD and MD values within the retrolenticular part of the internal capsule, the superior and anterior corona radiata, and the corpus callosum. Increased FA values in the left IFOF and the forceps minor correlated positively with verbal fluency scores. Altered RD parameters in the corticospinal tract and the forceps minor were associated with reduced visuomotor abilities.

CONCLUSIONS

The reported verbal fluency deficits and FA, RD and MD alterations in WM structures are potential cognitive and neural markers of BD. Abnormal RD values may be associated with progressive demyelination.

Evidence for cognitive subgroups in bipolar disorder and the influence of subclinical depression and sleep disturbances

Recent research in bipolar disorder (BD) points to the relevance and persistence of cognitive deficits even in euthymia. Up to now, the mechanisms behind why some bipolar patients (BP) do not reach their former level of cognitive performance and psychosocial functioning while others remit completely, are not understood. In this study we aimed to identify a "cognitive deficit" vs. "non-deficit" subgroup within BD by using an extensive neuropsychological test battery. The test performance of 70 euthymic outpatients (BD-I and II, recruited as a sample of convenience from our bipolar disorder programme) was compared to 70 matched, healthy controls (HC). Furthermore, we investigated the association between demographic/clinical variables and the cognitive performance of BP. As expected, our sample of euthymic BP performed significantly worse than HC in psychomotor speed, divided attention, working memory, verbal memory, word fluency and problem solving. However, 41.4% of the patients did not have any neurocognitive deficits at all, and whether or not a patient belonged to the non-deficit group was not influenced by disease severity. Instead, our results demonstrate that patients suffering from persistent sleep disturbances and sub-threshold depressive symptomatology show more severe cognitive dysfunctions. In addition, antipsychotic treatment and comorbid anxiety disorder were associated with cognitive deficits. In sum, these results suggest that a major part of cognitive impairment is due to current symptomatology, especially sleep disorder and sub-syndromal depression. Rigorous treatment of these symptoms thus might well improve cognitive deficits and, as a consequence, overall functioning in BD.

The neurocognitive functioning in bipolar disorder: a systematic review of data

BACKGROUND

During the last decades, there have been many different opinions concerning the neurocognitive function in Bipolar disorder (BD). The aim of the current study was to perform a systematic review of the literature and to synthesize the data in a comprehensive picture of the neurocognitive dysfunction in BD.

METHODS

Papers were located with searches in PubMed/MEDLINE, through June 1st 2015. The review followed a modified version of the recommendations of the Preferred Items for Reporting of Systematic Reviews and Meta-Analyses statement.

RESULTS

The initial search returned 110,403 papers. After the deletion of duplicates, 11,771 papers remained for further evaluation. Eventually, 250 were included in the analysis.

CONCLUSION

The current review supports the presence of a neurocognitive deficit in BD, in almost all neurocognitive domains. This deficit is qualitative similar to that observed in schizophrenia but it is less severe. There are no differences between BD subtypes. Its origin is unclear. It seems it is an enduring component and represents a core primary characteristic of the illness, rather than being secondary to the mood state or medication. This core deficit is confounded (either increased or attenuated) by the disease phase, specific personal characteristics of the patients (age, gender, education, etc.), current symptomatology and its treatment (especially psychotic features) and long-term course and long-term exposure to medication, psychiatric and somatic comorbidity and alcohol and/or substance abuse.

Emotion regulation strategies can predict task-switching abilities in euthymic bipolar patients

This study examined task-switching abilities and emotion regulation strategies in euthymic bipolar patients (EBP). Forty EBP and 40 healthy individuals performed face categorization tasks where they switched between emotion and non-emotion (i.e., gender) features among faces and completed emotion regulation questionnaire (Gross and John, 2003). Subject groups showed substantial differences in task-switching abilities and emotion regulation strategies: (1) there was a dissociation between emotion and gender classification in EBP. The switch cost was larger [i.e., higher reaction times (RTs) on switch as compared to no-switch trials] for gender categorization as compared to the emotion categorization task. In contrast, such asymmetries were absent among healthy participants. The differential pattern of task switching reflected functional disturbances in frontotemporal neural system and an attentional bias to emotion features of the faces in EBP. This suggests that when a euthymic bipolar patient is preoccupied with emotion recognition, an instruction to perform gender categorization results in greater cost on RTs. (2) In contrast to healthy individuals, EBP reported more frequent use of emotion suppression and lesser use of cognitive reappraisal as emotion regulation strategy. (3) Emotion regulation was found to be a significant predictor of task-switching abilities. It is argued that task switching deficits rely on maladaptive emotion regulation strategies in EBP specifically when tasks of emotional significance are involved.

Openness predicts cognitive functioning in bipolar disorder

OBJECTIVES

Openness to experience (O) is a well-established personality factor and is associated with cognitive performance. Little is known about the personality-cognitive relationship in bipolar disorder, an illness with significant variability in mood. Cognitive evaluation is essential in psychopathology assessment as it may reflect underlying disease processes and psychosocial functional capacity. Screening using a proxy personality variable may identify those in need of comprehensive cognitive testing. We hypothesized that O and measures of cognition would associate in both the Bipolar Disorder (BD) and healthy control (HC) samples, whereas neuroticism and extraversion would correlate with cognition only in the BD sample.

METHODS

Data from a longitudinal study of BD were used to study the association between personality factors and cognitive measures of attention, executive functioning, memory and fine motor skills. Regression analyses were used to determine the variables that account for the association between personality and cognition.

RESULTS

Aspects of O explained significant cognitive variance (~5%) in both groups; this persisted when demographic variables (including BD versus HC status) were considered. Neuroticism and extraversion did not consistently correlate with cognitive performance in either group.

LIMITATIONS

There were more females in the HC group who were slightly younger compared to the BD group. We lack direct measures of positive affect, and there is a reliance on a single measure of personality.

CONCLUSIONS

BD Individuals scoring low on self-reported Openness are potential candidates for more comprehensive cognitive assessments (which represent a limited resource).

Current Neural and Behavioral Dimensional Constructs across Mood Disorders

Our understanding of the underlying neurobiology for mood disorders is still limited. We present an integrated model for conceptualizing and understanding mood disorders drawing upon a broad literature pertinent to mood disorders. The integrated model of emotion processing and regulation incorporates the linguistic constructs of the Research Domain Criteria (RDoC) initiative. In particular, we focus on the Positive Valence domain/circuit (PVC), highlighting recent reward research and the Negative Valence domain/circuit (NVC), highlighting rumination. Furthermore, we also illustrate the Cognitive Control and Problem Solving (CCaPS) circuit, which is heavily involved in emotion regulation, as well as the default mode network (DMN) and interactions between circuits. We conclude by proposing methods for addressing challenges in the developmental study of mood disorders including using high-risk design that incorporates risk for many disorders.