Sex differences in cognitive functioning in patients with bipolar disorder who recently recovered from a first episode of mania: data from the Systematic Treatment Optimization Program for Early Mania (STOP-EM)

The impact of sex in the effectiveness of functional remediation in bipolar disorder

BACKGROUND

Functional recovery remains a core clinical objective for patients with bipolar disorder (BD). Sociodemographic, clinical, and neurocognitive variables are associated with long-term functional impairment, yet the impact of sex differences is unclear. Functional remediation (FR) is a validated intervention aimed at achieving functional recovery in BD. The present study assessed the effect of sex differences of FR on psychosocial functioning at post-treatment (6-months) and 12-month follow-up (FUP). To the best of our knowledge, this is the first study to explore the role of sex as a factor in the efficacy of FR.

METHODS

157 participants with BD were randomly assigned to either FR (N = 77) or treatment as usual group (80). Clinical, sociodemographic, neuropsychological, and functional data were obtained using a comprehensive assessment battery. Sex differences were explored via a general linear model (GLM) for repeated measures to compare the effect of sex on the intervention over time (6 months and FUP).

RESULTS

Results demonstrated that FR benefits both sexes, males (p = 0.001; d' = 0.88) and females (p = 0.04; d' = 0.57), at 6 months suggesting a generalized functional improvement. Conversely, at 12-month FUP sex differences were observed only in males (p = 0.005; d' = 0.68).

CONCLUSIONS

FR is a beneficial intervention for males and females after treatment, suggesting that there are no relevant distinct needs. Females may benefit from ongoing psychosocial functioning booster sessions after the intervention to maintain original improvements. Future research exploring sex differences could help to identify strategies to offer personalized FR intervention approaches in individuals with BD.

Verbal Learning and Memory Deficits across Neurological and Neuropsychiatric Disorders: Insights from an ENIGMA Mega Analysis

Deficits in memory performance have been linked to a wide range of neurological and neuropsychiatric conditions. While many studies have assessed the memory impacts of individual conditions, this study considers a broader perspective by evaluating how memory recall is differentially associated with nine common neuropsychiatric conditions using data drawn from 55 international studies, aggregating 15,883 unique participants aged 15-90. The effects of dementia, mild cognitive impairment, Parkinson's disease, traumatic brain injury, stroke, depression, attention-deficit/hyperactivity disorder (ADHD), schizophrenia, and bipolar disorder on immediate, short-, and long-delay verbal learning and memory (VLM) scores were estimated relative to matched healthy individuals. Random forest models identified age, years of education, and site as important VLM covariates. A Bayesian harmonization approach was used to isolate and remove site effects. Regression estimated the adjusted association of each clinical group with VLM scores. Memory deficits were strongly associated with dementia and schizophrenia (p < 0.001), while neither depression nor ADHD showed consistent associations with VLM scores (p > 0.05). Differences associated with clinical conditions were larger for longer delayed recall duration items. By comparing VLM across clinical conditions, this study provides a foundation for enhanced diagnostic precision and offers new insights into disease management of comorbid disorders.

Sex-differential cognitive performance on MCCB of youth with BD-II depression

BACKGROUND

Recent evidences have shown sex-differential cognitive deficits in bipolar disorder (BD) and differences in cognitions across BD subtypes. However, the sex-specific effect on cognitive impairment in BD subtype II (BD-II) remains obscure. The aim of the current study was to examine whether cognitive deficits differ by gender in youth with BD-II depression.

METHOD

This cross-sectional study recruited 125 unmedicated youths with BD-II depression and 140 age-, sex-, and education-matched healthy controls (HCs). The Chinese version of the Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) Consensus Cognitive Battery (MCCB) was used to assess cognitive functions. Mood state was assessed using the 24-item Hamilton Depression Rating Scale (24-HDRS) and the Young Mania Rating Scale (YMRS). Multivariate analysis of covariance (MANCOVA) was conducted.

RESULT

​Compared with HCs, patients with BD-II depression had lower scores on MCCB composite and its seven cognitive domains (all p < 0.001). After controlling for age and education, MANCOVA revealed significant gender-by-group interaction on attention/vigilance (F = 6.224, df = 1, p = 0.013), verbal learning (F = 9.847, df = 1, p = 0.002), visual learning (F = 4.242, df = 1, p = 0.040), and composite (F = 8.819, df = 1, p = 0.003). Post hoc analyses suggested that males performed worse in the above-mentioned MCCB tests than females in BD-II depression.

CONCLUSION

Our study demonstrated generalized cognitive deficits in unmedicated youths with BD-II depression. Male patients performed more serious cognitive impairment on attention/vigilance, verbal learning, and visual learning compared to female patients.

Risk of periodontitis in adolescents with bipolar disorder: a cohort study of 21,255 subjects

Although a growing number of studies have investigated the relationship between psychosocial factors and periodontitis, studies investigating the association between bipolar disorder (BD) and periodontitis are lacking. Using the Taiwan National Health Insurance Research Database, 4251 adolescents with BD and 17,004 age- and sex-matched controls were included. They were followed up from enrollment to the end of 2011 or death. Periodontitis was diagnosed during the follow-up. Cox regression analysis indicated that adolescents with BD had a higher risk of periodontitis (hazard ratio [HR]: 2.96, 95% confidence interval [CI] 2.77-3.17) than did controls. Subanalyses stratified by sex revealed a higher risk of periodontitis in male (HR: 2.83, 95% CI 2.56-3.14) and female (HR: 3.01, 95% CI 2.74-3.30) adolescents with BD than their respective controls. The long-term use of mood stabilizers was associated with a higher risk of periodontitis (HR: 1.19, 95% CI 1.06-1.35) in the BD cohort. Our study highlighted an increased risk of periodontitis in adolescents with BD compared with controls during the follow-up. We recommend that more attention should be paid to the prevention of periodontitis in adolescents with BD, especially those who are female or receiving mood stabilizers.

Sex differences in bipolar disorder: The dorsolateral prefrontal cortex as an etiopathogenic region

Bipolar disorder (BD) is worldwide a prevalent mental illness and a leading risk factor for suicide. Over the past three decades, it has been discovered that sex differences exist throughout the entire panorama of BD, but the etiologic regions and mechanisms that generate such differences remain poorly characterized. Available evidence indicates that the dorsolateral prefrontal cortex (DLPFC), a critical region that controls higher-order cognitive processing and mood, exhibits biological disparities between male and female patients with psychiatric disorders, which are highly correlated with the co-occurrence of psychotic symptoms. This review addresses the sex differences in BD concerning epidemiology, cognitive impairments, clinical manifestations, neuroimaging, and laboratory abnormalities. It also provides strong evidence linking DLPFC to the etiopathogenesis of these sex differences. We emphasize the importance of identifying gene signatures using human brain transcriptomics, which can depict sexually different variations, explain sex-biased symptomatic features, and provide novel targets for sex-specific therapeutics.

Sex Differences in Brain Disorders

A remarkable feature of the brain is its sexual dimorphism. Sexual dimorphism in brain structure and function is associated with clinical implications documented previously in healthy individuals but also in those who suffer from various brain disorders. Sex-based differences concerning some features such as the risk, prevalence, age of onset, and symptomatology have been confirmed in a range of neurological and neuropsychiatric diseases. The mechanisms responsible for the establishment of sex-based differences between men and women are not fully understood. The present paper provides up-to-date data on sex-related dissimilarities observed in brain disorders and highlights the most relevant features that differ between males and females. The topic is very important as the recognition of disparities between the sexes might allow for the identification of therapeutic targets and pharmacological approaches for intractable neurological and neuropsychiatric disorders.

Female advantage in verbal learning revisited: a HUNT study

The argument for a female advantage in word list learning is often based on partial observations that focus on a single component of the task. Using a large sample (N = 4403) of individuals 13-97 years of age from the general population, we investigated whether this advantage is consistently reflected in learning, recall, and recognition and how other cognitive abilities differentially support word list learning. A robust female advantage was found in all subcomponents of the task. Semantic clustering mediated the effects of short-term and working memory on long-delayed recall and recognition, and serial clustering on short-delayed recall. These indirect effects were moderated by sex, with men benefiting more from reliance on each clustering strategy than women. Auditory attention span mediated the effect of pattern separation on true positives in word recognition, and this effect was stronger in men than in women. Men had better short-term and working memory scores, but lower auditory attention span and were more vulnerable to interference both in delayed recall and recognition. Thus, our data suggest that auditory attention span and interference control (inhibition), rather than short-term or working memory scores, semantic and/or serial clustering on their own, underlie better performance on word list learning in women.

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

OBJECTIVE

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

METHOD

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

RESULTS

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

CONCLUSION

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

Sex differences in fronto-limbic white matter tracts in youth with mood disorders

AIMS

Patients with depression and bipolar disorder have previously been shown to have impaired white matter (WM) integrity compared with healthy controls. This study aimed to investigate potential sex differences that may provide further insight into the pathophysiology of these highly debilitating mood disorders.

METHODS

Participants aged 17 to 30 years (168 with depression [60% females], 107 with bipolar disorder [74% females], and 61 controls [64% females]) completed clinical assessment, self-report measures, and a neuropsychological assessment battery. Participants also underwent magnetic resonance imaging from which diffusion tensor imaging data were collected among five fronto-limbic WM tracts: cingulum bundle (cingulate gyrus and hippocampus subsections), fornix, stria terminalis, and the uncinate fasciculus. Mean fractional anisotropy (FA) scores were compared between groups using analyses of variance with sex and diagnosis as fixed factors.

RESULTS

Among the nine WM tracts analyzed, one revealed a significant interaction between sex and diagnosis, controlling for age. Male patients with bipolar disorder had significantly lower FA scores in the fornix compared with the other groups. Furthermore, partial correlations revealed a significant positive association between FA scores for the fornix and psychomotor speed.

CONCLUSIONS

Our findings suggest that males with bipolar disorder may be at increased risk of disruptions in WM integrity, especially in the fornix, which is thought to be responsible for a range of cognitive functions. More broadly, our findings suggest that sex differences may exist in WM integrity and thereby alter our understanding of the pathophysiology of mood disorders.

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.

Sex differences in neurocognitive and psychosocial functioning in bipolar disorder

BACKGROUND

Sex differences influence the clinical characteristics and course of illness of bipolar disorder (BD).

OBJECTIVE

Therefore, the aim of the present study was to examine the role of sex differences in neurocognitive performance and psychosocial functioning in a large sample of euthymic patients suffering from BD.

METHODS

The sample included 462 individuals, 347 patients with BD (148 males and 199 females) and 115 healthy controls (HC) (45 males and 70 females). Performance on a comprehensive neuropsychological battery assessing six cognitive domains and psychosocial functioning was compared between groups using linear mixed models, with sex and group as main effects, group by sex interactions and center as a random effect.

RESULTS

Males performed better than females in working memory (p < 0.001), whereas females outperformed males in the verbal learning (p = 0.03) and memory recognition (p = 0.03) tasks. No significant group by sex interactions were detected in cognitive performance. There were no overall sex differences or group by sex interactions in psychosocial functioning.

LIMITATIONS

Lack of assessment of visuo-spatial working memory.

CONCLUSIONS

There were no overall sex differences in neurocognition and psychosocial functioning. However, small sex differences in some measures of working memory and verbal memory were found. Individual differences of each patient, including sex perspective, should be considered in order to perform a tailored intervention plan adjusted to specific needs in the context of personalized treatment.

Sex differences in cognitive function of first-diagnosed and drug-naïve patients with bipolar disorder

BACKGROUND

Bipolar disorder (BD) is a severe mental illness that affects more than 1% the world's population with high recurrence rates and a series of comorbidities. Cognitive dysfunction is an endophenotype of BD, but sex influences in cognitive impairment remains unclear.

METHOD

We evaluated the performance of 139 patients with first-diagnosed, drug-naïve BD (44 males and 95 females) and 92 healthy controls (24 males and 68 females) using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) scale and the Stroop color-word test.

RESULT

Immediate memory, visuospatial/constructional ability, language, attention, delayed memory, total RBANS score, and Stroop color-word scores were significantly lower in patients with first-diagnosed, drug-naïve BD than healthy participants. Thus, male patients had worse attention and delayed memory scores compared with female patients with BD. Importantly, a worse performance in visuospatial/constructional ability was negatively associated with the Young Mania Rating Scale score in male patients only.

CONCLUSION

Male patients with first-diagnosed, drug-naïve bipolar disorder had worse cognitive dysfunction than female patients in attention and delayed memory. Cognitive deficits were correlated with mania severity only in male patients. These findings reveal the sexual dimorphism in the cognitive deficits of early BD patients with mild and moderated symptoms for further pathophysiological exploration.

The functional impairment of different subtypes and occupational states in euthymic patients with bipolar disorder

BACKGROUND

The aim was to explore the associations between clinical symptoms, demographic variables, social and neurocognitive functioning in euthymic patients with bipolar disorder (BD) stratified by subgroups of DSM-IV BD (type I (BD-I) and type II (BD-II)) and occupational status (employed/unemployed), and to highlight the significance of occupational status when assessing social and neurocognitive functioning in euthymic BD patients.

METHODS

A total of 81 euthymic BD patients were participated in the study. The severity of the depressive and manic/hypomanic symptoms was measured using the 17-item Hamilton Depression Rating Scale (HDRS-17) and the Young Mania Rating Scale (YMRS), respectively. Social functioning and neurocognitive functioning were evaluated by the Functioning Assessment Short Test (FAST) and neurocognitive measures, respectively.

RESULTS

Employed BD patients displayed greater social functioning (autonomy, occupational functioning, interpersonal relationship domain) and better verbal learning performance and speed of processing than unemployed BD patients. The correlation between neurocognitive functioning and social functioning was stronger in the employed group than in the unemployed group. There were no significant differences in neurocognitive and social functioning between the BD-I and BD-II groups, and the correlation between neurocognitive functioning and social functioning was similar between the BD-I and BD-II groups.

CONCLUSION

Employed BD patients may present greater occupational functioning and interpersonal relationships, as well as better verbal learning performance and speed of processing.

White Matter Microstructure in Individuals With and At Risk for Bipolar Disorder: Evidence for an Endophenotype From a Voxel-Based Meta-analysis

BACKGROUND

Aberrant white matter (WM) microstructure has been proposed as a mechanism underlying bipolar disorder (BD). Given the strong genetic underpinnings of both WM microstructure and BD, such WM aberrations may be not only a disease marker, but also an endophenotype of BD. If so, they should be observable in individuals at risk for BD (AR) (i.e., first-degree relatives). This meta-analysis integrates evidence on perturbed WM microstructure in individuals with or at risk for BD.

METHODS

A comprehensive search of literature published through April 2020 identified diffusion tensor imaging studies that used a voxel-based approach to compare fractional anisotropy (FA) and radial diffusivity between individuals with BD and/or AR individuals and healthy volunteers. Effect size comparison and conjunction analysis allowed identification of endophenotypes and disease markers of BD. Effects of age, sex, mood state, and psychotropic medication were explored using meta-regressions.

RESULTS

We included 57 studies in individuals with BD (N = 4631) and 10 in AR individuals (N = 753). Both individuals with and at risk for BD were associated with lower FA in the body and splenium of the corpus callosum. In the BD group, decreased FA and increased radial diffusivity comprised the entire corpus callosum, anterior thalamic radiation, fronto-orbito-polar tracts, and superior longitudinal fasciculus, and were influenced by age, sex, and mood state. Studies with higher proportions of individuals taking lithium or antipsychotics reported smaller FA reductions in BD.

CONCLUSIONS

Findings suggest that abnormalities in the body and splenium of the corpus callosum may be an endophenotype for BD, and they associate BD with WM tracts relevant for working memory performance, attention, and reward processing.

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

OBJECTIVE

To perform a systematic review and meta-analysis of executive functions (EF) and episodic memory in bipolar disorder (BD).

METHODS

A literature search was conducted on three electronic databases. Results were combined using random-effects meta-analysis.

RESULTS

A total of 126 studies (6424 patients with BDI, 702 with BDII, and 8276 controls) were included. BDI was associated with moderate to large impairments across all cognitive functions and BDII with small-to-medium impairments. Small significant differences were identified between BDI and BDII on all cognitive functions except inhibition. The Trail Making Test (TMT) (g = 0.74, 95% CI: 0.67-0.80), Hayling Test (g = 0.58, 95% CI: 0.34-0.81), Digit Span Total (g = 0.79, 95% CI: 0.57-1.01), and Category Fluency (g = 0.59, 95% CI: 0.45-0.72) tasks were most sensitive to cognitive impairment in BDI. The TMT (g = 0.65, 95% CI: 0.50-0.80) and Category Fluency (g = 0.56, 95% CI: 0.37-0.75) were also sensitive to cognitive alterations in patients with BDII.

CONCLUSION

BD type I was associated with more severe and widespread impairments than BDII, which showed smaller impairments on all functions except inhibition, where impairments were larger. Education and (hypo)manic symptoms should be further investigated in future studies due to their possible influence on the neuropsychological profile of BD. The instruments identified in this review should be considered for inclusion in cognitive assessment batteries in BD.

Sex differences in schizophrenia, bipolar disorder, and post-traumatic stress disorder: Are gonadal hormones the link?

In this review, we describe the sex differences in prevalence, onset, symptom profiles, and disease outcome that are evident in schizophrenia, bipolar disorder, and post-traumatic stress disorder. Women with schizophrenia tend to exhibit less disease impairment than men. By contrast, women with post-traumatic stress disorder are more affected than men. The most likely candidates to explain these sex differences are gonadal hormones. This review details the clinical evidence that oestradiol and progesterone are dysregulated in these psychiatric disorders. Notably, existing data on oestradiol, and to a lesser extent, progesterone, suggest that low levels of these hormones may increase the risk of disease development and worsen symptom severity. We argue that future studies require a more inclusive, considered analysis of gonadal steroid hormones and the intricacies of the interactions between them, with methodological rigour applied, to enhance our understanding of the roles of steroid hormones in psychiatric disorders. LINKED ARTICLES: This article is part of a themed section on The Importance of Sex Differences in Pharmacology Research. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.21/issuetoc.

The brief assessment of cognition in affective disorders: Normative data for the Italian population

BACKGROUND

To date there are no validated tests in Italian to assess cognitive functions in Bipolar Disorder. Therefore, this study aimed to provide normative data for the Italian version of the Brief Assessment of Cognition in Affective Disorders (BAC-A), a battery targeting neuro- and affective-cognition in affective disorders.

METHODS

Data were collected from 228 healthy participants (age range: 18-67; mean age: 34.68 ± 12.15 years) across eight recruiting sites. The influence of age, sex and education was measured and adjusted for using multivariate stepwise regression models. Normative values were established by means of the Equivalent Score approach.

RESULTS

Most of the BAC-A subtests showed patterns of association with age (inversely associated with overall cognitive performance), education (positively associated with Verbal Memory and Fluency, Digit Sequencing and Affective Processing subtests) and sex (females performed better than males in the Affective Interference Test but worse in the Emotion Inhibition Task, Digit Sequencing and Tower of London).

LIMITATIONS

The sample size was not sufficiently large for developing stratified norms, using 10-years ranges. Moreover, the participants included in the study were, on average, highly educated.

CONCLUSIONS

The normative data of the BAC-A provided in this study can serve as a cognitive functioning reference for Italian-speaking participants within the age range of the study sample. This can increase the applicability of this test in both clinical and research settings. The reliability and validity of the Italian BAC-A need to be further investigated.

Social cognition in bipolar disorder: the role of sociodemographic, clinical, and neurocognitive variables in emotional intelligence

OBJECTIVE

The main aims of this study were to examine the differences in the Emotional Intelligence (EI), the emotional domain of social cognition (SC), between euthymic patients with bipolar disorder (BD) and healthy controls (HC) and to evaluate the contribution of sociodemographic, clinical, and neuropsychological variables to EI.

METHODS

We recruited 202 patients with BD and 50 HC. EI was evaluated using the Mayer-Salovey-Caruso Emotional Intelligence Test (MSCEIT). The sociodemographic, clinical, and neurocognitive variables that showed a significant association with EI were entered into hierarchical multiple regression analysis.

RESULTS

BD patients obtained significantly lower scores compared to HC in the Emotional Intelligence Quotient (EIQ) and in the Understanding Emotions branch score. The best fitting model for the variables associated with EI in the patients group was a linear combination of gender, estimated IQ, family history of affective diagnosis, and executive function. The model, including these previous variables, explained up to 27.6% of the observed variance (R²  = 0.276, F = 16.406, P < 0.001).

CONCLUSIONS

The identification of variables associated with deficit in EI, such as male gender, lower estimated IQ, family history of affective diagnosis. and lower executive function performance, may help in selecting treatment targets to improve SC, and especially EI, in patients with BD.

Sex-related variation of neurocognitive functioning in bipolar disorder: Focus on visual memory and associative learning

Bipolar disorder (BD) is associated with cognitive deficits in attention, verbal memory and executive functions. However, only few studies have examined sex effects on cognition despite their clinical relevance. Given that visual memory/ learning has been understudied the aim of our study was to investigate sex-related variation in cognition (executive functions and visual memory/ learning) in BD. Cognitive performance of 60 bipolar-I patients and 30 healthy controls was evaluated by using CANTAB battery tasks targeting spatial memory (SRM), paired associative learning (PAL) and executive functions. We fitted a multivariate analysis of covariance (MANCOVA), followed by task-specific ANCOVAs. A significant diagnosis by sex interaction effect was detected (MANCOVA); specifically, diagnosis-specific sex effects were found for SRM and PAL, as healthy males outperformed healthy females but this pattern was attenuated in BD patients. Patients' clinicodemographic characteristics, current psychopathology or medication status did not differ across sexes and were, therefore, unlikely to explain detected sex effects. Our study is one of few studies to assess sex-related variation in cognition in BD and the first to record a diagnosis-specific sex effect for two tasks of visuo-spatial memory/ learning, indicating that sex-related variation in healthy subjects is disrupted in BD.

Sex differences of hippocampal structure in bipolar disorder

Although differential patterns in clinical characteristics have been consistently noted between male and female patients with bipolar disorder (BD), the effect of sex on the hippocampal structure remains unclear. To address this, the present study investigated the effects of BD and sex on the hippocampal structure, and the relationship between the hippocampal structure and cognitive performance. Morphometric and neurocognitive analyses were performed in 91 subjects (patients with BD: male/female = 33/19; normal controls: male/female = 22/17). Patients had significantly decreased left parahippocampal gyrus area and left/right hippocampal volume compared to normal controls. Within the BD group only, female patients presented with smaller right hippocampal volume than males. In the Spatial Span (SS) test (used to assess working memory capacity) and the Maze test (used to evaluate the ability to anticipate), patients demonstrated decreased performance compared to normal controls, with a significant main effect of sex. Left parahippocampal gyrus area and right hippocampal volume were positively correlated with SS and Maze in patients; moreover, right hippocampal volume predicted 17.4% of SS performance variance. These results suggest that there may be a difference between male and female patients with regard to right hippocampal volume, and that female patients may need more attention than males.

Gender differences in C-reactive protein and homocysteine modulation of cognitive performance and real-world functioning in bipolar disorder

BACKGROUND

Cognitive and psychosocial impairment has been associated with increased levels of C-reactive protein (CRP) and homocysteine in bipolar disorder, but gender differences have seldom been studied.

METHODS

Two hundred and twenty-four bipolar outpatients were included. Cognitive performance was assessed through the Screen for Cognitive Impairment in Psychiatry (SCIP). Psychosocial functioning was evaluated using the Functioning Assessment Short Test (FAST) and the General Assessment of Functioning (GAF). Homocysteine and CRP levels were determined. Separate analyses were performed by gender. Partial correlations were calculated to test for associations between biomarkers and cognitive and psychosocial functioning. Hierarchical multiple regression was used to assess factors predicting cognitive and psychosocial functioning. Covariates were: age, education, duration of illness, hospital admissions, depressive symptoms, tobacco consumption, and BMI.

RESULTS

A better performance was noted in women in delayed verbal learning (p = 0.010), along with better occupational functioning (p = 0.027) and greater leisure time impairment (p = 0.034). In men, CRP and homocysteine levels were associated with psychosocial dysfunction (interpersonal relationships and financial functioning, respectively). In women, CRP levels correlated with cognitive performance (SCIP total raw score, immediate and delayed verbal learning, and verbal fluency). CRP was a predictor of cognitive performance in women only.

LIMITATIONS

The choice of the cognitive scale and covariates and the lack of a control group may be the main limitations.

CONCLUSIONS

A gender difference was found in biomarker modulation of cognition and psychosocial functioning. A gender-based approach to cognition and real-world functioning should be considered in bipolar disorder to ensure an optimal outcome.

Sex differences in visual-spatial working memory: A meta-analysis

Visual-spatial working memory measures are widely used in clinical and experimental settings. Furthermore, it has been argued that the male advantage in spatial abilities can be explained by a sex difference in visual-spatial working memory. Therefore, sex differences in visual-spatial working memory have important implication for research, theory, and practice, but they have yet to be quantified. The present meta-analysis quantified the magnitude of sex differences in visual-spatial working memory and examined variables that might moderate them. The analysis used a set of 180 effect sizes from healthy males and females drawn from 98 samples ranging in mean age from 3 to 86 years. Multilevel meta-analysis was used on the overall data set to account for non-independent effect sizes. The data also were analyzed in separate task subgroups by means of multilevel and mixed-effects models. Results showed a small but significant male advantage (mean d = 0.155, 95 % confidence interval = 0.087-0.223). All the tasks produced a male advantage, except for memory for location, where a female advantage emerged. Age of the participants was a significant moderator, indicating that sex differences in visual-spatial working memory appeared first in the 13-17 years age group. Removing memory for location tasks from the sample affected the pattern of significant moderators. The present results indicate a male advantage in visual-spatial working memory, although age and specific task modulate the magnitude and direction of the effects. Implications for clinical applications, cognitive model building, and experimental research are discussed.

Influences of patient informed cognitive complaints on activities of daily living in patients with bipolar disorder. An exploratory cross-sectional study

Many patients with bipolar disorder (BD) experience debilitating cognitive deficits, with risk of impaired occupational and psychosocial functioning. However, knowledge of how these deficits impact the patients' ability to perform Activities of Daily Living (ADL), tasks related to self-care and domestic life is limited. We explored the relation between impaired cognitive function and the ability to perform ADL in patients with BD. A total of 42 outpatients (mean age 36 years (range 19.0-58.0 years), 69% women) with BD in remission and with subjective cognitive complaints (≥ 13 on the Cognitive Complaints in Bipolar Disorder Rating Assessment questionnaire (COBRA)) were included. Objective neurocognitive function was evaluated with a short comprehensive cognitive test battery and ADL ability was evaluated with the performance-based Assessment of Motor and Process Skills (AMPS) in the homes of the patients. Our findings indicate that low processing speed correlated with decreased ADL ability, and processing speed as measured by the cognitive test battery thus seems to be significantly related to patients' ability to live independently in the community. Overall, adding a performance based test to assess ADL ability in patients with BD home-surroundings seems to provide new insights regarding the effect of cognitive impairment in patients with BD.

A Swedish National Prospective and Co-relative Study of School Achievement at Age 16, and Risk for Schizophrenia, Other Nonaffective Psychosis, and Bipolar Illness

While cognitive ability is inversely associated with risk for schizophrenia (SZ), the association is less clear with other nonaffective psychoses (ONAP) and bipolar illness (BPI). Using national Swedish hospital registry data, we examined the prospective relationship between school achievement (SA) and development of SZ, ONAP, and BPI in 1800643 adolescents born 1972-1990. We used Cox proportional hazard and co-relative control models to predict onset of SZ, ONAP, and BPI from standardized SA scores at age 16. The hazard ratio (HRs; and 95% CIs) for first onset of SZ as a function of SA was 0.66 (0.64-0.68) for both sexes. For ONAP, the HRs equaled 0.66 (0.64-0.68) for males and 0.72 (0.70-0.75) for females. For BPI, parallel HRs were 0.81 (0.78-0.84) and 0.71 (0.70-0.73). The association between SA and risk was stronger in the lower vs the higher ranges of SA. In most analyses, moderate increases in risk were observed at the highest levels of SA, with the strongest evidence for females and risk of ONAP. Co-relative control analyses indicated that common genetic or familial-environmental effects only marginally confounded these associations. Consistent with prior studies, these results have 3 major implications for neurodevelopmental models: (1) adolescent cognitive deficits that increase risk are not the result of prodromal changes,( 2) individual specific environmental exposures are largely responsible for the association between low SA and psychosis risk, and (3) neurodevelopmental disturbances (as indicated by low SA) are not unique to SZ but also occur in ONAP and to a lesser degree BPI.

Meta-analysis of Cognitive Impairment in First-Episode Bipolar Disorder: Comparison With First-Episode Schizophrenia and Healthy Controls

Neurocognitive deficits are evident both in established schizophrenia and bipolar disorder (BP). However, it has been suggested that schizophrenia, but not BP, is characterized by neurodevelopmental abnormalities that can lead to cognitive deficits at the earliest stages of the illness. The aim of this meta-analytic review was to compare neurocognitive deficits in first-episode BP (FEBP) with healthy controls and first-episode schizophrenia (FES) patients. The current meta-analysis included a total of 22 adult studies and involved comparisons of 533 FEBP patients with 1417 healthy controls and 605 FEBP and 822 FES patients. FEBP patients were significantly impaired in all cognitive domains (d = 0.26-0.80) and individual tasks (d = 0.22-0.66) investigated. FES patients significantly underperformed FEBP patients in most cognitive domains (d = 0.05-0.63) and on individual tasks (d = 0.13-0.77). Neuropsychological impairment, which is comparable to chronic BP, was evident in FEBP. Similar to chronic patients, cognitive functions in FEBP lie intermediate between FES and healthy controls. Neurodevelopmental factors are likely to play a significant role not only in schizophrenia but also in BP.

Cognitive impairment in first-episode mania: a systematic review of the evidence in the acute and remission phases of the illness

There is evidence of cognitive impairment that persists in the remission phase of bipolar disorder; however, the extent of the deficits that occur from the first onset of the disorder remains unclear. This is the first systematic review on cognitive functioning in the early stages of bipolar I disorder. The aim of the study was to identify the patterns and degree of cognitive impairment that exists from first-episode mania. Three electronic databases (MEDLINE, PsycINFO and PubMed) were systematically searched for studies published from January 1980 to June 2014. Eligible studies were separated into two groups: acute and remission. The Newcastle-Ottawa quality assessment scale was utilised to measure the quality of the included studies. A total of seven studies (three acute and four remission), including 230 first-episode mania and 345 healthy control participants, were eligible for the review. The studies in the acute phase only examined aspects of executive functioning, with impairments identified in cognitive flexibility, though not in response inhibition and verbal fluency relative to healthy controls. The most consistent finding during the remission phase was a deficit in working memory, whereas in the other domains, the findings were equivocal. Non-verbal memory and verbal fluency were not impacted in remission from first-episode mania. In conclusion, deficits are present in some but not all areas of cognitive functioning during the early stages of bipolar I disorder. Further research is warranted to understand the longitudinal trajectory of change from first-episode mania.

Neurocognitive functioning in the premorbid stage and in the first episode of bipolar disorder: a systematic review

It is well known that patients with bipolar disorder (BD) have cognitive impairments even during periods of euthymia. However, to date it remains unclear the moment when these deficits onset. Therefore, the aim of this study was to review the evidence focusing on the cognitive status of patients with BD in their premorbid stage and in their first episode. An extensive search was conducted through the online databases Pubmed/PsychInfo, covering the period between 1980 and 2014. A total of 23 studies were selected for the review (nine studies explored premorbid stage of people who lately develop BD and 14 examined first-episodes in bipolar patients). There is evidence that general intelligence is not impaired in the premorbid stage. Impairments in verbal memory, attention, and executive functions tend to be present during and after the first episode. Preliminary evidence suggests that these deficits in specific cognitive domains might precede the onset of illness.

Developmental trajectory of cognitive impairment in bipolar disorder: comparison with schizophrenia

Both schizophrenia and bipolar disorder (BP) are associated with neurocognitive deficits. However, it has been suggested that schizophrenia, but not BP, is characterised by premorbid cognitive impairments and neurodevelopmental abnormalities. In this paper, studies investigating neurocognitive deficits in premorbid, high-risk and first-episode BP were reviewed and these findings were compared with outcome of studies in schizophrenia. Available evidence suggests that cognitive deficits are evident in first-episode BP and such deficits can be evident even years before the onset of the illness in some patients. Trajectory of cognitive deficits from childhood to adulthood can be very similar in schizophrenia and many patients with BP. Developmental lag in acquisition of cognitive skills is a risk factor for both disorders. However, unlike schizophrenia, not only impaired cognition but also supranormal premorbid cognitive/scholastic performance predict BP. Neurodevelopmental cognitive impairment is evident in some but not all patients with BP. A model suggesting that only BP patients who share common genetic risk factors with schizophrenia have premorbid neurodevelopmental cognitive deficits is proposed. In this model, combination of absence of neurodevelopmental abnormalities and BP-related temperamental characteristics explains the relationship between supranormal cognition and risk for BP.