Neurocognitive heterogeneity in patients with bipolar disorder and their unaffected relatives: associations with emotional cognition

Implementing cognitive screenings for outpatients with bipolar disorder following optimised treatment in a specialised mood disorder clinic

Bipolar disorder (BD) is often accompanied by persistent cognitive impairment. However, screening for cognitive impairment in the clinic is challenged by a lack of consensus on screening procedures. This study assesses cognitive impairment prevalence and screening feasibility in alignment with the International Society for Bipolar Disorder Targeting Cognition Task Force recommendations. Between January 2022 and May 2023, 136 newly diagnosed BD outpatients were assessed with the Screen for Cognitive Impairment in Psychiatry after 15-20 months of specialised care at the Copenhagen Affective Disorder Clinic. Cognitive impairment patterns and associations with cognitive complaints, perceived stress, and functioning were examined. Most screened patients (73 %) achieved full or partial remission, with 51 % being cognitively normal, 38 % showing global impairments, and 11 % displaying selective impairments. Among remitted patients, 56 % were cognitively normal, while 31 % and 13 % exhibited global or selective impairments, respectively. Both objectively impaired patient groups reported more subjective cognitive difficulties than those who were cognitively normal. The globally impaired group also demonstrated poorer functioning, more depressive symptoms and lower quality of life than cognitively normal patients. Across all patients, lower cognitive performance correlated with more cognitive complaints, lower functioning, lower quality of life, and more depressive symptoms. Cognitive screenings were relatively easily implementable, involving only a 1.5 h session including mood ratings, feedback and cognitive strategy discussion. The study highlights the clinical relevance and feasibility of cognitive screenings in BD patients, emphasizing the need for tailored interventions given frequent cognitive impairment in clinically stable individuals.

Increased grey matter volumes in the temporal lobe and its relationship with cognitive functioning in euthymic patients with bipolar disorder

BACKGROUND

Bipolar disorder (BD) is characterized by episodic mood dysregulation, although a significant portion of patients suffer persistent cognitive impairment during euthymia. Previous magnetic resonance imaging (MRI) research suggests BD patients may have accelerated brain aging, observed as lower grey matter volumes. How these neurostructural alterations are related to the cognitive profile of BD is unclear.

METHODS

We aim to explore this relationship in euthymic BD patients with multimodal structural neuroimaging. A sample of 27 euthymic BD patients and 24 healthy controls (HC) underwent structural grey matter MRI and diffusion-weighted imaging (DWI). BD patient's cognition was also assessed. FreeSurfer algorithms were used to obtain estimations of regional grey matter volumes. White matter pathways were reconstructed using TRACULA, and four diffusion metrics were extracted. ANCOVA models were performed to compare BD patients and HC values of regional grey matter volume and diffusion metrics. Global brain measures were also compared. Bivariate Pearson correlations were explored between significant brain results and five cognitive domains.

RESULTS

Euthymic BD patients showed higher ventricular volume (F(1, 46) = 6.04; p = 0.018) and regional grey matter volumes in the left fusiform (F(1, 46) = 15.03; pFDR = 0.015) and bilateral parahippocampal gyri compared to HC (L: F(1, 46) = 12.79, pFDR = 0.025/ R: F(1, 46) = 15.25, pFDR = 0.015). Higher grey matter volumes were correlated with greater executive function (r = 0.53, p = 0.008).

LIMITATIONS

We evaluated a modest sample size with concurrent pharmacological treatment.

CONCLUSIONS

Higher medial temporal volumes in euthymic BD patients may be a potential signature of brain resilience and cognitive adaptation to a putative illness neuroprogression. This knowledge should be integrated into further efforts to implement imaging into BD clinical management.

Stable neural underpinnings of emotional cognition subgroups in patients newly diagnosed with bipolar disorder: A prospective fMRI study

OBJECTIVES

This study aimed to investigate the neural underpinnings of emotional cognition subgroups in recently diagnosed patients with bipolar disorder (BD) and change over time over a 15-month follow-up period.

METHODS

Patients and healthy controls (HC) underwent emotional and nonemotional cognitive assessments and functional magnetic resonance imaging (fMRI) at the baseline (BD n = 87; HC n = 65) and at 15-month follow-up (BD n = 44; HC n = 38). Neural activity during emotion reactivity and regulation in response to aversive pictures was assessed during fMRI. Patients were clustered into subgroups based on their emotional cognition and, with HC, were compared longitudinally on cognition and neural activity during emotion reactivity and regulation.

RESULTS

Patients were optimally clustered into two subgroups: Subgroup 1 (n = 40, 46%) was characterized by heightened emotional reactivity in negative social scenarios, which persisted over time, but were otherwise cognitively intact. This subgroup exhibited stable left amygdala hyper-activity over time during emotion reactivity compared to subgroup 2. Subgroup 2 (n = 47, 54%) was characterized by global emotional cognitive impairments, including stable difficulties with emotion regulation over time. During emotion regulation across both time points, this group exhibited hypo-activity in the left dorsolateral prefrontal cortex. Additionally, patients in subgroup 2 had poorer nonemotional cognition, had more psychiatric hospital admissions and history of psychotic episodes than those in subgroup 1.

CONCLUSIONS

Broad impairments in emotional cognition in approximately half of BD patients and associated nonemotional cognitive deficits may originate from insufficient recruitment of prefrontal resources, contributing to poorer clinical outcomes.

Socio-economic status, functioning and cognition in young versus adult patients newly diagnosed with bipolar disorder and their unaffected relatives; results from a cross-sectional study

BACKGROUND

Bipolar disorders (BD) figures on top of the World Health Organization classification of disabling disorders. It is unclear if there are socioeconomic, functioning, and cognition differences in young patients newly diagnosed with BD and whether these are different for young and adult patients newly diagnosed with BD. Understanding these differences is important for tailored treatment and support.

METHODS

Participant groups included 401 patients newly diagnosed with BD, 145 of their unaffected first-degree relatives (UR) and 209 healthy control individuals (HC). First, we compared socio-economic status, functioning and cognition between young patients newly diagnosed with BD (150), UR (61) and HC (92) (15-25 years) and adult patients newly diagnosed with BD (251), UR (84) and HC (117) (>25 years), respectively. Second, within patients, we compared functioning and cognition between young and adult patients newly diagnosed with BD.

RESULTS

In both participant groups, patients newly diagnosed with BD, and to a lesser degree UR, had lower socio-economic status and impaired functioning and cognition compared with HC. Further, young patients newly diagnosed with BD were less functionally impaired, than adults newly diagnosed with BD, whereas cognition did not differ between groups.

LIMITATIONS

Applied tools for assessments of functioning and cognition are not validated below age 18.

CONCLUSIONS

Overall, lower socio-economic status and impaired functioning and cognition were found both in young and adult patients newly diagnosed with BD and their UR compared with young and adult HC, respectively. Young patients were less functionally impaired than adults, but cognition was similarly impaired.

Neurocognition across bipolar disorder phases compared to healthy subjects

INTRODUCTION

Bipolar disorder (BD) is associated with cognitive abnormalities that may persist during euthymia and are linked to poor occupational performance. The cognitive differences between phases of BD are not well known. Therefore, a cross-sectional study with a relatively large population was conducted to evaluate the differences among BD phases in a wide range of neurocognitive parameters.

METHODS

Neuropsychological profile of 169 patients with a diagnosis of BD in manic, depressive, mixed, and euthymic phases between the ages of 18 and 70 years were compared to 45 healthy individuals' between ages of 24 and 69 years. The working memory (digit-span backward test), face recognition, executive functions (verbal fluency and Stroop test), face recognition, and visual and verbal memory (immediate and delayed recall) were evaluated. For BD subgroup analyses, we used the Kruskal-Wallis (KW) test. Then, for the comparison of BD versus healthy individuals, we used the Mann-Whitney U (MWU) test.

RESULTS

Analyses based on non-parametric tests showed impairments in BD for all tests. There were no significant differences between phases.

CONCLUSION

Cognitive performance in patients with BD appears to be mostly unrelated to the phase of the disorder, implying that cognitive dysfunction in BD is present even during remission.

Functional Alterations in Patients with Bipolar Disorder and Their Unaffected First-Degree Relatives: Insight from Genetic, Epidemiological, and Neuroimaging Data

Bipolar disorder (BD) profoundly affects cognitive and psychosocial functioning, leading to a significant illness burden on patients and their families. Genetic factors are predominant in the onset of bipolar disorder and functional impairments. This disorder exhibits a strong family aggregation, with heritability estimates reaching up to 80%. Individuals with BD often experience impaired functioning, especially in significant areas such as physical performance, sleep, cognition, interpersonal interactions, socioeconomic status, family and marital relationships, work and school performance, well-being, and life expectancy. However, patients with different subtypes exhibit significant heterogeneity in social functioning, cognition, and creativity levels. There are notable differences in psychosocial and cognitive function in their unaffected first-degree relatives (UFR) who do not suffer but may carry susceptibility genes compared to healthy control (HC) without a family history. The observations indicate common genetic structures between BD patients and their UFR, which results in varying degrees of functional abnormalities. Therefore, this article mainly provides evidence on cognition, creativity, and psychosocial functioning in patients with BD and their UFR to provide a more comprehensive understanding of this critical topic in the field of BD. By integrating various findings, including clinical data and neuroimaging studies, our article aims to provide insights and valuable information for a deeper exploration of the pathogenesis of BD and the development of more targeted therapeutic strategies in the future.

Associations between aberrant working memory-related neural activity and cognitive impairments in somatically healthy, remitted patients with mood disorders

BACKGROUND

Persistent cognitive deficits are prevalent in patients with bipolar disorder (BD) and unipolar disorder (UD), but treatments effectively targeting cognition in these mood disorders are lacking. This is partly due to poor insight into the neuronal underpinnings of cognitive deficits.

METHODS

The aim of this functional magnetic resonance imaging (fMRI) study was to investigate the neuronal underpinnings of working memory (WM)-related deficits in somatically healthy, remitted patients with BD or UD (n = 66) with cognitive and functional impairments compared to 38 healthy controls (HC). The participants underwent neuropsychological testing and fMRI, while performing a visuospatial and a verbal N-back WM paradigm.

RESULTS

Relative to HC, patients exhibited hypo-activity across dorsolateral prefrontal cortex as well as frontal and parietal nodes of the cognitive control network (CCN) and hyper-activity in left orbitofrontal cortex within the default mode network (DMN) during both visuospatial and verbal WM performance. Verbal WM-related response in the left posterior superior frontal gyrus (SFG) within CCN was lower in patients and correlated positively with out-of-scanner executive function performance across all participants.

CONCLUSIONS

Our findings suggest that cognitive impairments across BD and UD are associated with insufficient recruitment of task-relevant regions in the CCN and down-regulation of task-irrelevant orbitofrontal activity within the DMN during task performance. Specifically, a lower recruitment of the left posterior SFG within CCN during verbal WM was associated with lower cognitive performance.

Association between childhood trauma, cognition, and psychosocial function in a large sample of partially or fully remitted patients with bipolar disorder and healthy participants

BACKGROUND

Childhood trauma (CT) are frequently reported by patients with bipolar disorder (BD), but it is unclear whether and how CT contribute to patients' cognitive and psychosocial impairments. We aimed to examine the impact of CT on cognition and psychosocial functioning in a large sample of 345 patients with BD and 183 healthy control participants (HC) using the Childhood Trauma Questionnaire, neurocognitive tests and ratings of mood symptoms and functioning.

RESULTS

Patients showed broad cognitive impairments across memory, attention and executive function and functional disability despite being in partial or full remission and had higher levels of CT than HC. Higher levels of CT correlated with impairments across almost all cognitive domains and lower psychosocial functioning across BD patients and HC. Of these, the associations between CT and poorer working memory and lower psychosocial functioning, respectively, prevailed after adjusting for clinical and demographical variables. Diagnosis of BD and estimated verbal intelligence did not moderate these associations. Analysis of CT sub-categories showed that working memory impairments were related particularly to childhood physical and emotional abuse, while psychosocial difficulties were related to physical and emotional neglect.

CONCLUSIONS

CT may have negative implications for working memory and psychosocial functioning across both BD and healthy populations. If the findings are replicated, this would suggest that early interventions that reduce the frequency of CT in vulnerable families may aid children's cognitive and psychosocial development.

Neurocognitive subgroups among newly diagnosed patients with schizophrenia spectrum or bipolar disorders: A hierarchical cluster analysis

Studies across schizophrenia (SZ) and bipolar disorder (BD) indicate common transdiagnostic neurocognitive subgroups. However, existing studies of patients with long-term illness precludes insight into whether impairments result from effects of chronic illness, medication or other factors. This study aimed to investigate whether neurocognitive subgroups across SZ and BD can be demonstrated during early illness stages. Data from overlapping neuropsychological tests were pooled from cohort studies of antipsychotic-naïve patients with first-episode SZ spectrum disorders (n = 150), recently diagnosed BD (n = 189) or healthy controls (HC) (n = 280). Hierarchical cluster analysis was conducted to examine if transdiagnostic subgroups could be identified based on the neurocognitive profile. Patterns of cognitive impairments and patient characteristics across subgroups were examined. Patients could be clustered into two, three and four subgroups, of which the three-cluster solution (with 83% accuracy) was selected for posthoc analyses. This solution revealed a subgroup covering 39% of patients (predominantly BD) who were cognitively relatively intact, a subgroup of 33% of patients (more equal distributions of SZ and BD) displaying selective deficits, particularly in working memory and processing speed, and a subgroup of 28% (mainly SZ) with global impairments. The globally impaired group exhibited lower estimated premorbid intelligence than the other subgroups. Globally impaired BD patients also showed more functional disability than cognitively relatively intact patients. No differences were observed across subgroups in symptoms or medications. Neurocognitive results can be understood by clustering analysis with similar clustering solutions occurring across diagnoses. The subgroups were not explained by clinical symptoms or medication, suggesting neurodevelopmental origins.

Association of childhood trauma with cognitive impairment and structural brain alterations in remitted patients with bipolar disorder

BACKGROUND

Cognitive impairment affects many patients with bipolar disorder (BD). No pro-cognitive treatment with robust efficacy exists partly due to limited insight into underlying neurobiological abnormalities.

METHODS

This magnetic resonance imaging (MRI) study investigates structural neuronal correlates of cognitive impairment in BD by comparing brain measures in a large sample of cognitively impaired versus cognitively intact patients with BD or cognitively impaired patients with major depressive disorder (MDD) and healthy controls (HC). Participants underwent neuropsychological assessments and MRI scans. The cognitively impaired and - intact BD and MDD patient groups were compared with each other and HC regarding prefrontal cortex measures, hippocampus shape/volume, and total cerebral white (WM) and grey matter (GM).

RESULTS

Cognitively impaired BD patients showed lower total cerebral WM volume than HC, which scaled with poorer global cognitive performance and more childhood trauma. Cognitively impaired BD patients also showed lower adjusted GM volume and thickness in the frontopolar cortex than HC but greater adjusted GM volume in the temporal cortex than cognitively normal BD patients. Cognitively impaired BD patients showed decreased cingulate volume than cognitively impaired MDD patients. Hippocampal measures were similar across all groups.

LIMITATIONS

The cross-sectional study design prevented insights into causal relationships.

CONCLUSIONS

Lower total cerebral WM and regional frontopolar and temporal GM abnormalities may constitute structural neuronal correlates of cognitive impairment in BD, of which the WM deficits scale with the degree of childhood trauma. The results deepen the understanding of cognitive impairment in BD and provide a neuronal target for pro-cognitive treatment development.

The Big Five as Predictors of Cognitive Function in Individuals with Bipolar Disorder

The connection between cognitive function and the "Big Five" personality traits (openness, conscientiousness, extraversion, agreeableness, and neuroticism) in the general population is well known; however, studies researching bipolar disorder (BD) are scarce. Therefore, this study aimed to investigate the Big Five as predictors of executive function, verbal memory, attention, and processing speed in euthymic individuals with BD (cross-sectional: n = 129, including time point t1; longitudinal: n = 35, including t1 and t2). Participants completed the NEO Five-Factor Inventory, the Color and Word Interference Test, the Trail Making Test, the d2 Test of Attention Revised, and the California Verbal Learning Test. The results showed a significant negative correlation between executive function and neuroticism at t1. Changes in cognitive function between t1 and t2 did not correlate with and could not be predicted by the Big Five at t1. Additionally, worse executive function at t2 was predicted by higher neuroticism and lower conscientiousness at t1, and high neuroticism was a predictor of worse verbal memory at t2. The Big Five might not strongly impact cognitive function over short periods; however, they are significant predictors of cognitive function. Future studies should include a higher number of participants and more time in between points of measurement.

Neural basis of memory impairments and relation to functional disability in fully or partially remitted patients with affective disorders

Bipolar disorder (BD) and major depressive disorder (MDD) are associated with cognitive and functional impairment. Cognitive impairment is often associated with dorsal prefrontal cortex (dPFC) hypo-activity, but the neuronal correlates of functional disability is largely unknown. In this study, 91 patients with affective disorders in full or partial remission (BD, n = 67; MDD, n = 24) with objectively verified cognitive impairment and substantial functional disability underwent neuropsychological assessment and functional magnetic resonance imaging (fMRI) scan during which they completed a strategic picture-encoding task. For comparison, 36 matched healthy controls underwent an identical test protocol. Patients showed encoding-related hypo-activity in the dPFC compared to controls. In patients, lower right dlPFC activity was associated with poorer overall functioning and more antipsychotic drug use. In conclusion, memory impairments were underpinned by failure to recruit the dPFC during task performance which was associated with impaired functioning in fully or partially remitted patients with affective disorders. This aberrant neurocircuitry activity has implications for the design of future pro-cognitive interventions that aim to improve not only cognition but also real-world functioning.

The longitudinal trajectory of emotional cognition in subgroups of recently diagnosed patients with bipolar disorder

Although cross-sectional studies show heterogeneity in emotional cognition in bipolar disorder (BD), the temporal course within subgroups is unclear. In this prospective, longitudinal study we assessed the trajectories of emotional cognition subgroups within a 16-month follow-up period in recently diagnosed BD patients compared to healthy controls (HC). Recently diagnosed BD patients and HC underwent comprehensive emotional and non-emotional testing at baseline and again at follow-up. We employed hierarchical cluster analysis at baseline to identify homogenous emotional cognition subgroups of patients, and changes across the subgroups of BD and HC were assessed with linear mixed-model analyses. We found two emotional cognition subgroups: subgroup 1 (65%, n = 179), showing heightened negative emotional reactivity in neutral and negative social scenarios and faster recognition of emotional facial expressions than HC (ps<0.001, n = 190), and subgroup 2 (35%, n = 96) showing blunted reactivity in positive social scenarios, impaired emotion regulation, poorer recognition of positive and slower recognition of all facial expressions than HC (ps≤.03). Subgroup 1 exhibited normalization of the initial emotional cognition abnormalities in follow-up. In contrast, subgroup 2 showed a lack of improvement in reactivity positively-valenced emotional information. Patients in subgroup 2 presented more and longer mixed episodes during the follow-up time and were more often prescribed lithium. One third of patients display blunted emotional reactivity, impaired emotion regulation abilities and facial expression recognition difficulties also show persistent impairments and poorer course of illness. This subgroup may indicate a need for earlier and more targeted therapeutic interventions.

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

BACKGROUND

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

METHODS

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

RESULTS

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

LIMITATIONS

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

CONCLUSION

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

The longitudinal trajectory of emotion regulation and associated neural activity in patients with bipolar disorder: A prospective fMRI study

OBJECTIVES

Impaired emotion regulation is a key feature of bipolar disorder (BD) that presents during acute mood episodes and in remission. The neural correlates of voluntary emotion regulation seem to involve deficient prefrontal top-down regulation already at BD illness onset. However, the trajectory of aberrant neuronal activity during emotion regulation in BD is unclear.

METHODS

We investigated neural activity during emotion regulation in response to aversive pictures from the International Affective Picture System in patients with recently diagnosed BD (n = 43) in full or partial remission and in healthy controls (HC) (n = 38) longitudinally at baseline and 16 months later.

RESULTS

Patients with BD exhibited stable hypo-activity in the left dorsomedial prefrontal cortex (DMPFC) and right dorsolateral prefrontal cortex (DLPFC) and impaired emotion regulation compared to HC over the 16 months follow-up time. More DLPFC hypo-activity during emotion regulation correlated with less successful down-regulation (r = 0.16, p = 0.045), more subsyndromal depression (r = -0.18, p = 0.02) and more functional impairment (r = -0.24, p = 0.002), while more DMPFC hypo-activity correlated with less efficient emotion regulation (r = 0.16, p = 0.048). Finally, more DMPFC hypo-activity during emotion regulation at baseline was associated with an increased likelihood of subsequent relapse during the 16 months follow-up time (β = -2.26, 95% CI [0.01; 0.99], p = 0.048).

CONCLUSION

The stable DLPFC and DMPFC hypo-activity during emotion regulation represents a neuronal trait-marker of persistent emotion regulation difficulties in BD. Hypo-activity in the DMPFC may contribute to greater risk of relapse.

Clinical research diagnostic criteria for bipolar illness (CRDC-BP): rationale and validity

BACKGROUND

In the 1970 s, scientific research on psychiatric nosology was summarized in Research Diagnostic Criteria (RDC), based solely on empirical data, an important source for the third revision of the official nomenclature of the American Psychiatric Association in 1980, the Diagnostic and Statistical Manual, Third Edition (DSM-III). The intervening years, especially with the fourth edition in 1994, saw a shift to a more overtly "pragmatic" approach to diagnostic definitions, which were constructed for many purposes, with research evidence being only one consideration. The latest editions have been criticized as failing to be useful for research. Biological and clinical research rests on the validity of diagnostic definitions that are supported by firm empirical foundations, but critics note that DSM criteria have failed to prioritize research data in favor of "pragmatic" considerations.

RESULTS

Based on prior work of the International Society for Bipolar Diagnostic Guidelines Task Force, we propose here Clinical Research Diagnostic Criteria for Bipolar Illness (CRDC-BP) for use in research studies, with the hope that these criteria may lead to further refinement of diagnostic definitions for other major mental illnesses in the future. New proposals are provided for mixed states, mood temperaments, and duration of episodes.

CONCLUSIONS

A new CRDC could provide guidance toward an empirically-based, scientific psychiatric nosology, and provide an alternative clinical diagnostic approach to the DSM system.

Neural underpinnings of emotion regulation subgroups in remitted patients with recently diagnosed bipolar disorder

Neuroimaging studies of bipolar disorder (BD) generally involve comparison with healthy controls (HC), which may mask neurobiological variability within the disorder. This study aims to assess the neural underpinnings of potential subgroups of BD patients based on functional activity in the emotion regulation network and its relation to illness characteristics and relapse risk. Eighty-seven remitted patients with recently diagnosed BD and 66 HC underwent functional magnetic resonance imaging (fMRI) while performing an emotion regulation task. Patients were re-assessed with clinical interviews after 16 (±5) months. Data-driven hierarchical cluster analysis was employed to investigate 'neuronal subgroups' of patients based on their neuronal activity in a pre-defined emotion regulation network. Relations between neuronal subgroups and illness characteristics and relapse rates were examined. Patients were allocated into two subgroups. Subgroup 1 (n=62, 75%) was characterized by exaggerated bilateral amygdala reactivity but normal prefrontal and temporo-parietal activation. Subgroup 2 (n= 22, 25%) showed widespread hypo-activity within all emotion regulation regions. Both subgroups were less successful at down-regulating their emotions than HC (F(2,146)=5.33, p=.006, η_p²=.07). Patients in subgroup 2 had a history of more and longer mixed episodes (ps≤.01). Importantly, heightened amygdala activity across all patients was associated with increased risk of relapse during a 16-month follow-up period (β=3.36, 95% CI [1.49;550.35], N=60, p=.03). The identified neuronal subgroups of patients with either amygdala hyper-activity or broad network hypo-activity during emotion regulation points to neurobiological heterogeneity among remitted patients with BD. Heightened amygdala reactivity may be a neuronal target for personalized treatments to prevent relapse.

Identifying social cognition subgroups in euthymic patients with bipolar disorder: a cluster analytical approach

BACKGROUND

Bipolar disorder (BD) is associated with social cognition (SC) impairments even during remission periods although a large heterogeneity has been described. Our aim was to explore the existence of different profiles on SC in euthymic patients with BD, and further explore the potential impact of distinct variables on SC.

METHODS

Hierarchical cluster analysis was conducted using three SC domains [Theory of Mind (ToM), Emotional Intelligence (EI) and Attributional Bias (AB)]. The sample comprised of 131 individuals, 71 patients with BD and 60 healthy control subjects who were compared in terms of SC performance, demographic, clinical, and neurocognitive variables. A logistic regression model was used to estimate the effect of SC-associated risk factors.

RESULTS

A two-cluster solution was identified with an adjusted-performance group (N = 48, 67.6%) and a low-performance group (N = 23, 32.4%) with mild deficits in ToM and AB domains and with moderate difficulties in EI. Patients with low SC performance were mostly males, showed lower estimated IQ, higher subthreshold depressive symptoms, longer illness duration, and poorer visual memory and attention. Low estimated IQ (OR 0.920, 95% CI 0.863-0.981), male gender (OR 5.661, 95% CI 1.473-21.762), and longer illness duration (OR 1.085, 95% CI 1.006-1.171) contributed the most to the patients clustering. The model explained up to 35% of the variance in SC performance.

CONCLUSIONS

Our results confirmed the existence of two discrete profiles of SC among BD. Nearly two-thirds of patients exhibited adjusted social cognitive abilities. Longer illness duration, male gender, and lower estimated IQ were associated with low SC performance.

The long-term course of cognition in bipolar disorder: a systematic review and meta-analysis of patient-control differences in test-score changes

Neuropsychological impairment represents a key aspect of bipolar disorder (BD) that is evident even in early-course patients and is a strong predictor of functional outcomes among those affected. Previous meta-analyses of longitudinal studies suggest that BD-related cognitive deficits may not progress along the course of the disorder. However, short test-retest periods were used in most primary studies and comparisons with healthy controls were limited. The aim of this review was to synthesize the findings of research reports comparing long-term neurocognitive trajectories between BD patients and healthy individuals. PubMed, PsycINFO, and Scopus databases were searched from inception through July 2021. Publications were considered for inclusion if they reported cognitive test scores of BD patients and healthy controls at two different time points, with a minimum test-retest interval of 5 years. Fifteen studies compared the long-term course of cognition in BD patients with that of healthy controls. Ten of these were included in the quantitative analysis and involved 540 BD patients and 644 healthy individuals (mean follow-up period: 8.9 years). Patient-control effect sizes (standardized mean differences) were calculated for test-score changes in 24 neuropsychological variables and combined by means of meta-analytic procedures. No significant differences were found between patients and controls regarding long-term cognitive outcomes. These findings are consistent with previous shorter-term longitudinal meta-analyses and do not provide evidence for progressive cognitive deterioration in most bipolar individuals. Future studies should address the longitudinal course of cognition in different subgroups of BD patients and its prognostic and therapeutic value.

Assessment of the neuronal underpinnings of cognitive impairment in bipolar disorder with a picture encoding paradigm and methodological lessons learnt

BACKGROUND

Mood disorders are often associated with persistent cognitive impairments. However, pro-cognitive treatments are essentially lacking. This is partially because of poor insight into the neurocircuitry abnormalities underlying these deficits and their change with illness progression.

AIMS

This functional magnetic resonance imaging (fMRI) study investigates the neuronal underpinnings of cognitive impairments and neuronal change after mood episodes in remitted patients with bipolar disorder (BD) using a hippocampus-based picture encoding paradigm.

METHODS

Remitted patients with BD (n=153) and healthy controls (n=52) were assessed with neuropsychological tests and underwent fMRI while performing a strategic picture encoding task. A subgroup of patients (n=43) were rescanned after 16 months. We conducted data-driven hierarchical cluster analysis of patients' neuropsychological data and compared encoding-related neuronal activity between the resulting neurocognitive subgroups. For patients with follow-up data, effects of mood episodes were assessed by comparing encoding-related neuronal activity change in BD patients with and without episode(s).

RESULTS

Two neurocognitive subgroups were revealed: 91 patients displayed cognitive impairments while 62 patients were cognitively normal. No neuronal activity differences were observed between neurocognitive subgroups within the dorsal cognitive control network or hippocampus. However, exploratory whole-brain analysis revealed lower activity within a small region of middle temporal gyrus in impaired patients, which significantly correlated with poorer neuropsychological performance. No changes were observed in encoding-related neuronal activity or picture recall accuracy with the occurrence of mood episode(s) during the follow-up period.

CONCLUSION

Memory encoding fMRI paradigms may not capture the neuronal underpinnings of cognitive impairment or effects of mood episodes.

Affective and non-affective cognition in patients with bipolar disorder type I and type II in full or partial remission: Associations with familial risk

BACKGROUND

The upcoming conversion of the ICD-11 will subdivide patients with bipolar disorder (BD) into BD type I (BD-I) and BD type II (BD-II). This study aimed to investigate whether cognitive impairments could aid as objective cognitive biomarkers for recently diagnosed BD subtypes by comparing cognitive profiles between BD subtypes, their unaffected relatives (UR), and healthy controls (HC).

METHODS

The sample included 76 patients with BD-I, 149 patients with BD-II, 28 UR of patients with BD-I (UR-I), 50 UR of patients with BD-II (UR-II) and 168 HC from the Bipolar Illness Onset study, who were assessed with an extensive non-affective and affective cognitive test battery.

RESULTS

The results showed no significant differences in affective or non-affective cognition between BD-I and BD-II. Compared to HC, patients with BD-I (but not BD-II) showed worse performance in verbal fluency (p = .01) and were slower at recognising fearful faces (p = .045), while patients with BD-II (but not BD-I) displayed generally poorer recognition of facial expressions (p = .02). Only UR-I showed lower performance on verbal fluency (p = .049) and aberrant affective cognition (ps≤.047) compared to HC.

LIMITATIONS

The potential confounding effects of medication were not explored.

CONCLUSIONS

The lack of significant differences in cognitive profiles between recently diagnosed BD-I and BD-II suggests that neither affective nor non-affective cognition are indicative of BD subtype.

Norms for the Screen for Cognitive Impairment in Psychiatry and cognitive trajectories in bipolar disorder

BACKGROUND

The International Society for Bipolar Disorders Targeting Cognition Task Force recommends screening for and monitoring of cognitive impairments in patients with bipolar disorder (BD) with the Screen for Cognitive Impairment in Psychiatry (SCIP). The study aimed to provide the first demographically adjusted norms and change norms for the SCIP and to compare the cognitive trajectory over one year in remitted BD patients with normative cognitive change.

METHODS

Patients with fully or partially remitted BD and healthy controls (HC) were assessed with the SCIP at baseline and at a one-year follow-up. Regression-based models were used to determine demographically adjusted norms and change norms. Using the change models, predicted follow-up scores were calculated for BD and HC, and independent t-tests were used to compare deviations of the observed from the predicted follow-up scores for BD vs. HC to assess differences in cognitive trajectories.

RESULTS

Baseline data were collected for n=273 HC and n=218 BD, and follow-up data for n=139 HC and n=74 BD. Baseline norm models included age, sex and years of education, while change models included baseline SCIP scores and age. Patients with follow-up data showed selective impairments within verbal learning and recall at baseline. They followed the normative cognitive trajectories for all cognitive domains but verbal learning.

LIMITATIONS

Cognition was assessed with a screening tool.

CONCLUSIONS

We recommend implementing demographically adjusted norms and change norms for the SCIP in clinical and research settings. Change norms seem sensitive to subtle and selective cognitive decline over one year in remitted BD.