Prevalence and determinants of cognitive impairment in the euthymic phase of bipolar disorders: results from the FACE-BD cohort

Functioning and neurocognition in very early and early-life onset bipolar disorders: the moderating role of bipolar disorder type

Defining homogeneous subgroups of bipolar disorder (BD) is a major goal in personalized psychiatry and research. According to the neurodevelopmental theory, age at onset may be a key variable. As potential trait markers of neurodevelopment, cognitive and functional impairment should be greater in the early form of the disease, particularly type 1 BD (BD I). The age at onset was assessed in a multicenter, observational sample of 4190 outpatients with BD. We used a battery of neuropsychological tests to assess six domains of cognition. Functioning was measured using the Functioning Assessment Short Test (FAST). We studied the potential moderation of the type of BD on the associations between the age at onset and cognitive and functioning in a subsample of 2072 euthymic participants, controlling for potential clinical and socio-demographic covariates. Multivariable analyses showed cognition to not be impaired in individuals with early (21-30 years) and very early-life (before 14 years) onset of BD. Functioning was equivalent between individuals with early and midlife-onset of BD II and NOS but better for individuals with early onset of BD I. In contrast, functioning was not worse in individuals with very early-onset BD I but worse in those with very early-onset BD II and NOS. Early-life onset BDs were not characterized by poorer cognition and functioning. Our results do not support the neurodevelopmental view that a worse cognitive prognosis characterizes early-life onset BD. This study suggests that functional remediation may be prioritized for individuals with midlife-onset BD I and very early life onset BD 2 and NOS.

Comparative analysis of anticholinergic burden scales to explain iatrogenic cognitive impairment and self-reported side effects in the euthymic phase of bipolar disorders: Results from the FACE-BD cohort

Bipolar disorders (BD) are characterized by cognitive impairment during the euthymic phase, to which treatments can contribute. The anticholinergic properties of medications, i.e., the ability of a treatment to inhibit cholinergic receptors, are associated with cognitive impairment in elderly patients and people with schizophrenia but this association has not been well characterized in individuals with remitted BD. Moreover, the validity of only one anticholinergic burden scale designed to assess the anticholinergic load of medications has been tested in BD. In a literature review, we identified 31 existing scales. We first measured the associations between 27 out of the 31 scales and objective cognitive impairment in bivariable regressions. We then adjusted the bivariable models with covariates: the scales significantly associated with cognitive impairment in bivariable and multiple logistic regressions were defined as having good concurrent validity to assess cognitive impairment. In a sample of 2,031 individuals with euthymic BD evaluated with a neuropsychological battery, two scales had good concurrent validity to assess cognitive impairment, whereas chlorpromazine equivalents, lorazepam equivalents, the number of antipsychotics, or the number of treatments had not. Finally, similar analyses with subjective anticholinergic side-effects as outcome variables reported 14 scales with good concurrent validity to assess self-reported peripheral anticholinergic side-effects and 13 to assess self-reported central anticholinergic side-effects. Thus, we identified valid scales to monitor the anticholinergic burden in BD, which may be useful in estimating iatrogenic cognitive impairment in studies investigating cognition in BD.

Altered intrinsic brain activity and cognitive impairment in euthymic, unmedicated individuals with bipolar disorder

Cognitive impairment in euthymic bipolar disorder (BD) contributes to poor functional outcomes. Resting-state magnetic resonance imaging (MRI)may help us understand the neurobiology of cognitive impairment in BD. Here, forty unmedicated euthymic BD patients and thirty-nine healthy controls were recruited, undergoing MRI scans and neuropsychological measures. The amplitude of low-frequency fluctuation (ALFF) and ALFF-based functional connectivity (FC) analysis was employed to explore the potential alterations of neural activity. Voxel-wised correlation was calculated between clinical and cognitive variables and abnormal brain activity. Compared with healthy controls, euthymic BD patients showed worse cognitive performance in Trail Making Test, Digit Span Test, and Stroop Color-Word Test (SCWT). The euthymic BD group had significantly lower ALFF in the left medial frontal gyrus, right middle frontal gyrus, right postcentral gyrus, and left superior frontal gyrus. Furthermore, we found decreased ALFF values in the right middle frontal gyrus that was negatively correlated with cognitive inhibition, (r = -0.43, P = 0.015). ALFF-based FC analysis showed that BD group showed significantly decreased FC between the right middle frontal gyrus (seed) and left middle temporal gyrus and left medial frontal gyrus, (Two-tailed, P_FWE < 0.05, TFCE corrected). The findings demonstrated that individuals with BD during the euthymic phase exhibited decreased ALFF and hypoconnectivity of key brain areas within the frontoparietal network. These altered spontaneous brain activity in euthymic BD patients may be involved in the pathophysiology mechanism of cognitive deficits.

Differences of resting fMRI and cognitive function between drug-naïve bipolar disorder and schizophrenia

BACKGROUND

Bipolar disorder (BD) and schizophrenia (SC) have many similarities in clinical manifestations. The acute phase of BD has psychotic symptoms, while SC also has emotional symptoms during the onset, which suggests that there is some uncertainty in distinguishing BD and SC through clinical symptoms.

AIM

To explore the characteristics of brain functional activities and cognitive impairment between BD and SC.

METHODS

Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) test was performed on patients in drug-naïve BD and SC (50 subjects in each group), and resting-state functional magnetic resonance imaging (rs-fMRI) scanning was performed meanwhile. Rs-fMRI data were routinely preprocessed, and the value of the fractional amplitude of low-frequency fluctuation (fALFF) was calculated. Then each part of the scores of the RBANS and the characteristics of brain function activities were compared between the two groups. Finally used Pearson correlation to analyze the correlation between cognition and brain function.

RESULTS

(1) Compared with BD group, all parts of RBANS scores in SC group decreased; (2) The left inferior occipital gyrus (IOG, peak coordinates - 30, -87, -15; t = 4.78, voxel size = 31, Alphasim correction) and the right superior temporal gyrus (STG, peak coordinates 51, -12, 0; t = 5.08, voxel size = 17, AlphaSim correction) were the brain areas with significant difference in fALFF values between BD and SC. Compared with SC group, the fALFF values of the left IOG and the right STG in BD group were increased (p < 0.05); (3) Pearson correlation analysis showed that the visuospatial construction score was positively correlated with the fALFF values of the left IOG and the right STG (r_{left IOG} = 0.304, p = 0.003; r_{right STG} = 0.340, p = 0.001); The delayed memory (figure recall) score was positively correlated with the fALFF value of the left IOG (r_{left IOG} = 0.207, p = 0.044).

DISCUSSION

The cognitive impairment of SC was more serious than BD. The abnormal activities of the left IOG and the right STG may be the core brain region to distinguish BD and SC, and are closely related to cognitive impairment, which provide neuroimaging basis for clinical differential diagnosis and explore the pathological mechanism of cognitive impairment.

Cognitive profiles in bipolar I disorder and associated risk factors: Using Wechsler adult intelligence scale—IV

Background

Despite the growing evidence of cognitive impairments in bipolar disorder (BD), little work has evaluated cognitive performances utilizing the latest version of the Wechsler Intelligence Scale-IV (WAIS-IV), which is one of the most widely used neurocognitive assessments in clinical settings. Furthermore, clinical characteristics or demographic features that negatively affect the cognitive functioning of BD were not systematically compared or evaluated. Accordingly, the present study aimed to examine the cognitive profile of bipolar I disorder (BD-I) patients and associated risk factors.

Methods

Participants included 45 patients, diagnosed with BD-I, current or most recent episode manic, and matching 46 healthy controls (HC). Cognitive performance was evaluated via WAIS-IV, and clinical characteristics of the BD-I group were examined via multiple self- and clinician-report questionnaires.

Results

Multivariate analysis of covariance (MANCOVA) results indicated that the BD-I group demonstrated significantly poorer performance compared to the HC group in subtests and indexes that reflect working memory and processing speed abilities. Redundancy analysis revealed that overall symptom severity, manic symptom severity, and anxiety were significant predictors of cognitive performance in BD-I, while age of onset, past mood disorder history, depression severity, and impulsiveness showed comparatively smaller predictive values.

Conclusion

The current study suggests cognitive deterioration in the cognitive proficiency area while generalized ability, including verbal comprehension and most of the perceptual reasoning skills, remain intact in BD-I. The identified risk factors of cognitive performance provide specific clinical recommendations for intervention and clinical decision-making.

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.

Key findings on bipolar disorders from the longitudinal FondaMental Advanced Center of Expertise-Bipolar Disorder (FACE-BD) cohort

BACKGROUND

The FACE-BD cohort is an observational cohort of individuals with bipolar disorders (BD) who benefited from a systematic evaluation with evidence-based treatment recommendations and who were followed-up every year for 3 years in France. The objectives were to describe the lifetime course of BD, associated psychiatric and somatic comorbidities, and cognition profile. This cohort aims to identify clinical/biological signatures of outcomes, trajectories of functioning and transition between clinical stages. This article summarizes 10 years of findings of the FACE-BD cohort.

METHOD & RESULTS

We included 4422 individuals, all having a baseline assessment, among which 61.2% had at least one follow-up visit at either one, two or three years. A subsample of 1200 individuals had at least one biological sample (serum, plasma, DNA). Assessments include family history of psychiatric disorders, psychiatric diagnosis, current mood symptoms, functioning, hospitalizations, suicidal attempts, physical health, routine blood tests, treatment history, psychological dimensions, medico-economic data and a cognitive assessment. Studies from this cohort illustrate that individuals with BD display multiple coexistent psychiatric associated conditions including sleep disturbances, anxiety disorders, substance use disorders and suicide attempts as well as a high prevalence of metabolic syndrome. During follow-up, we observed a 55% reduction of the number of days of hospitalization and a significant improvement in functioning.

CONCLUSIONS

The FACE-BD cohort provides a strong research infrastructure for clinical research in BD and has a unique position among international cohorts because of its comprehensive clinical assessment and sustainable funding from the French Ministry of Health.

The impact of substance use disorder comorbidity on cognition of individuals with bipolar disorder: A systematic review

The aim of this study is to describe whether Bipolar Disorder (BD) with Substance Use Disorder (SUD) comorbidity is associated with an increased cognitive impairment as compared to BD without SUD comorbidity. This is a systematic review. The literature search was conducted in three databases: PubMed, PsycINFO and Embase. A total of 2032 studies were screened after removing duplicates. 29 articles were included for full text screening, and a total of 14 articles were included in the systematic review. Multiple cognitive domains were assessed, including verbal, spatial and visual memory, and psychomotor and executive functioning. Over half the articles (64.3%, n=9) identified cognitive impairments in individuals with BD+SUD comorbidity as compared to individuals with BD without SUD comorbidity. In addition, individuals with the comorbidity exhibited more severe impairments on tests of executive functioning, and greater impairments in verbal and visual memory. The studies included in this systematic review reinforce that individual with comorbidity of BD and SUD have increased cognitive impairment as compared to individuals with BD without SUD comorbidity. Executive functioning was the most impaired cognitive domain found across the studies included in this review. Intervention strategies focused on executive functioning would be beneficial for this specific population.

Correlation between cognitive performance and structural neuroanatomy in patients with type I bipolar affective disorder treated with and without lithium

INTRODUCTION

Lithium treatment of bipolar disorder (BD) has been associated with less cognitive impairment and fewer changes in structural brain anatomy compared to other treatments. However, the studies are heterogeneous and few assess whether these effects are related. The objective of this study was to evaluate and relate cognitive performance and structural neuroanatomy in patients treated with and without lithium.

METHODS

Cross-sectional study that included 48 subjects with BD-I, of which 22 were treated with lithium and 26 without lithium. Performance was assessed on Wechsler III (WAIS III), TMT A and B (Trial Making Test) neuropsychological tests, California verbal learning test (CVLT), Rey complex figure test and Wisconsin card sorting test. Brain structures obtained by magnetic resonance imaging (MRI) were evaluated. The standardised mean difference (SMD) between both groups was calculated, adjusted for confounding variables using a propensity score, and the Spearman correlation coefficient (ρ) was used to assess the relationship between cognitive performance and neuroanatomical regions.

RESULTS

Compared to the group without lithium, the group with lithium had fewer perseverative errors in the Wisconsin test (SMD = -0.69) and greater left and right cortical areas (SMD = 0.85; SMD = 0.92); greater surface area in the left anterior cingulate (SMD = 1.32), right medial orbitofrontal cortex (SMD = 1.17), right superior frontal gyrus (SMD = 0.82), and right and left precentral gyrus (SMD = 1.33; SMD = 0.98); greater volume of the right amygdala (SMD = 0.57), right hippocampus (SMD = 0.66), right putamen (SMD = 0.87) and right thalamus (SMD = .67). In the lithium group, a correlation was found with these errors and the thickness of the left precentral gyrus (ρ = -0.78), the volume of the right thalamus (ρ = -0.44), and the right amygdala (ρ = 0.6).

CONCLUSIONS

The lithium group had better cognitive flexibility and greater dimension in some frontal and subcortical cortical regions. Furthermore, there was a moderate to high correlation between performance in this executive function and the thickness of the right precentral gyrus, and the volumes of the thalamus and the right amygdala. These findings could suggest a neuroprotective effect of lithium.

Violent suicide attempt history in elderly patients with bipolar disorder: The role of sex, abdominal obesity, and verbal memory: Results from the FACE-BD cohort (FondaMental Advanced center of Expertise for Bipolar Disorders)

BACKGROUND

Bipolar disorder (BD) is a chronic, lifelong condition, associated with increased risk of obesity, cognitive impairment, and suicidal behaviors. Abdominal obesity and a higher risk of violent suicide attempt (SA) seem to be shared correlates with older age, BD, and male sex until middle age when menopause-related female body changes occur. This study aimed at assessing the role of abdominal obesity and cognition in the violent SA burden of individuals with BD.

METHODS

From the well-defined nationwide cohort FACE-BD (FondaMental Advanced center of Expertise for Bipolar Disorders), we extracted data on 619 euthymic BD patients that were 50 years or older at inclusion. Cross-sectional clinical, cognitive, and metabolic assessments were performed. SA history was based on self-report.

RESULTS

Violent SA, in contrast to non-violent and no SA, was associated with higher waist circumference, abdominal obesity and poorer California Verbal Learning Test short-delay free recall (CVLT-SDFR) (ANOVA, p < .001, p = .014, and p = .006). Waist circumference and abdominal obesity were associated with violent SA history independently of sex, BD type and anxiety disorder (Exp(B) 1.02, CI 1.00-1.05, p = .018; Exp(B) 2.16, CI 1.00-4.64, p = .009, accordingly). In an exploratory model, waist circumference and CVLT-SDFR performance mediated the association between male sex and violent SA.

LIMITATIONS

Cross-sectional design and retrospective reporting.

CONCLUSIONS

Violent SA history was associated with abdominal obesity and poorer verbal memory in older age BD patients. These factors were interlinked and might mediate the association between male sex and violent SA.

Reaction Time and Visual Memory in Connection to Alcohol Use in Persons with Bipolar Disorder

The purpose of this study was to explore the association of cognition with hazardous drinking and alcohol-related disorder in persons with bipolar disorder (BD). The study population included 1268 persons from Finland with bipolar disorder. Alcohol use was assessed through hazardous drinking and alcohol-related disorder including alcohol use disorder (AUD). Hazardous drinking was screened with the Alcohol Use Disorders Identification Test for Consumption (AUDIT-C) screening tool. Alcohol-related disorder diagnoses were obtained from the national registrar data. Participants performed two computerized tasks from the Cambridge Automated Neuropsychological Test Battery (CANTAB) on A tablet computer: the 5-choice serial reaction time task, or reaction time (RT) test and the Paired Associative Learning (PAL) test. Depressive symptoms were assessed with the Mental Health Inventory with five items (MHI-5). However, no assessment of current manic symptoms was available. Association between RT-test and alcohol use was analyzed with log-linear regression, and eβ with 95% confidence intervals (CI) are reported. PAL first trial memory score was analyzed with linear regression, and β with 95% CI are reported. PAL total errors adjusted was analyzed with logistic regression and odds ratios (OR) with 95% CI are reported. After adjustment of age, education, housing status and depression, hazardous drinking was associated with lower median and less variable RT in females while AUD was associated with a poorer PAL test performance in terms of the total errors adjusted scores in females. Our findings of positive associations between alcohol use and cognition in persons with bipolar disorder are difficult to explain because of the methodological flaw of not being able to separately assess only participants in euthymic phase.

Long-term trajectory of cognitive performance in people with bipolar disorder and controls: 6-year longitudinal study

BACKGROUND

Cross-sectional studies have found impaired cognitive functioning in patients with bipolar disorder, but long-term longitudinal studies are scarce.

AIMS

The aims of this study were to examine the 6-year longitudinal course of cognitive functioning in patients with bipolar disorder and healthy controls. Subsets of patients were examined to investigate possible differences in cognitive trajectories.

METHOD

Patients with bipolar I disorder (n = 44) or bipolar II disorder (n = 28) and healthy controls (n = 59) were tested with a comprehensive cognitive test battery at baseline and retested after 6 years. We conducted repeated measures ANCOVAs with group as a between-subject factor and tested the significance of group and time interaction.

RESULTS

By and large, the change in cognitive functioning between baseline and follow-up did not differ significantly between participants with bipolar disorder and healthy controls. Comparing subsets of patients, for example those with bipolar I and II disorder and those with and without manic episodes during follow-up, did not reveal subgroups more vulnerable to cognitive decline.

CONCLUSIONS

Cognitive performance remained stable in patients with bipolar disorder over a 6-year period and evolved similarly to healthy controls. These findings argue against the notion of a general progressive decline in cognitive functioning in bipolar disorder.

Neurocognitive profiles of patients with first-episode and recurrent depression: a cross-sectional comparative study from China

BACKGROUND

Accumulating evidence has shown that cognitive deficits are prevalent among patients with major depressive disorder (MDD). However, the pattern and extent of cognitive deficits in patients with first-episode and recurrent depression remain unclear.

METHODS

Objective measures of cognitive function were assessed in 433 first-episode of depression (FED) patients, 206 recurrent major depression (RMD) patients during the acute phase and 287 healthy controls (HCs). Five domains of cognition (speed of processing, attention, verbal learning, visual learning and execution function) were assessed by seven neuropsychological tests. Neuropsychological data were transformed into T scores according to the Chinese norm.

RESULTS

Both FED and RMD patients displayed deficits of mild-to-medium severity across all cognitive domains and their subtests, relative to HCs (Cohen's d = 0.12-0.62). Among MDD patients, RMD patients exhibited poorer verbal learning (Cohen's d = 0.17) and visual learning (Cohen's d = 0.21) than FED patients.

CONCLUSIONS

MDD patients in the acute phase exhibited broad cognitive impairments, and there were significant differences in verbal and visual learning between FED and RMD patients. Our findings indicate that more attention should be paid to the domains of verbal and visual learning in future screening assessments and targeted interventions.

Longitudinal relationships between cognition and functioning over 2 years in euthymic patients with bipolar disorder: a cross-lagged panel model approach with the FACE-BD cohort

BACKGROUND

Longitudinal studies of the relationship between cognition and functioning in bipolar disorder are scarce, although cognition is thought to be a key determinant of functioning. The causal structure between cognition and psychosocial functioning in bipolar disorder is unknown.

AIMS

We sought to examine the direction of causality between cognitive performance and functional outcome over 2 years in a large cohort of euthymic patients with bipolar disorder.

METHOD

The sample consisted of 272 adults diagnosed with bipolar disorder who were euthymic at baseline, 12 and 24 months. All participants were recruited via the FondaMental Advanced Centers of Expertise in Bipolar Disorders. We used a battery of tests, assessing six domains of cognition at baseline and 24 months. Residual depressive symptoms and psychosocial functioning were measured at baseline and 12 and 24 months. The possible causal structure between cognition and psychosocial functioning was investigated with cross-lagged panel models with residual depressive symptoms as a covariate.

RESULTS

The analyses support a causal model in which cognition moderately predicts and is causally primary to functional outcome 1 year later, whereas psychosocial functioning does not predict later cognitive performance. Subthreshold depressive symptoms concurrently affected functioning at each time of measure.

CONCLUSIONS

Our results are compatible with an upward causal effect of cognition on functional outcome in euthymic patients with bipolar disorder. Neuropsychological assessment may help specify individual prognoses. Further studies are warranted to confirm this causal link and evaluate cognitive remediation, before or simultaneously with functional remediation, as an intervention to improve functional outcome.

Correlation Between Cognitive Performance and Structural Neuroanatomy in Patients with Type I Bipolar Affective Disorder Treated with and Without Lithium

INTRODUCTION

Lithium treatment of bipolar disorder (BD) has been associated with less cognitive impairment and fewer changes in structural brain anatomy compared to other treatments. However, the studies are heterogeneous and few assess whether these effects are related. The objective of this study was to evaluate and relate cognitive performance and structural neuroanatomy in patients treated with and without lithium.

METHODS

Cross-sectional study that included 48 subjects with BD-I, of which 22 were treated with lithium and 26 without lithium. Performance was assessed on Wechsler III (WAIS III), TMT A and B (Trial Making Test) neuropsychological tests, California verbal learning test (CVLT), Rey complex figure test and Wisconsin card sorting test. Brain structures obtained by magnetic resonance imaging (MRI) were evaluated. The standardised mean difference (SMD) between both groups was calculated, adjusted for confounding variables using a propensity score, and the Spearman correlation coefficient (ρ) was used to assess the relationship between cognitive performance and neuroanatomical regions.

RESULTS

Compared to the group without lithium, the group with lithium had fewer perseverative errors in the Wisconsin test (SMD = -0.69) and greater left and right cortical areas (SMD = 0.85; SMD = 0.92); greater surface area in the left anterior cingulate (SMD = 1.32), right medial orbitofrontal cortex (SMD = 1.17), right superior frontal gyrus (SMD = 0.82), and right and left precentral gyrus (SMD = 1.33; SMD = 0.98); greater volume of the right amygdala (SMD = 0.57), right hippocampus (SMD = 0.66), right putamen (SMD = 0.87) and right thalamus (SMD=.67). In the lithium group, a correlation was found with these errors and the thickness of the left precentral gyrus (ρ = -0.78), the volume of the right thalamus (ρ =-0.44), and the right amygdala (ρ = 0.6).

CONCLUSIONS

The lithium group had better cognitive flexibility and greater dimension in some frontal and subcortical cortical regions. Furthermore, there was a moderate to high correlation between performance in this executive function and the thickness of the right precentral gyrus, and the volumes of the thalamus and the right amygdala. These findings could suggest a neuroprotective effect of lithium.

Minimum clinically important differences for the Functioning Assessment Short Test and a battery of neuropsychological tests in bipolar disorders: results from the FACE-BD cohort

AIMS

Establishing the minimum clinically important difference (MCID) in functioning and cognition is essential to the interpretation of the research and clinical work conducted in bipolar disorders (BD). The present study aimed to estimate the MCID for the Functioning Assessment Short Test (FAST) and a battery of neuropsychological tests in BD.

METHODS

Anchor-based and distributive methods were used to estimate the MCID for the FAST and cognition using data from a large, multicentre, observational cohort of individuals with BD. The FAST and cognition were linked with the Clinical Global Impressions Scale-Severity (CGI-S) and Global Assessment of Functioning (GAF) using an equipercentile method. The magnitude of the standard error measurement (s.e.m.) provided another estimate of the MCID.

RESULTS

In total, 570 participants were followed for 2 years. Cross-sectional CGI-S and GAF scores were linked to a threshold ⩽7 on the FAST for functional remission. The MCID for the FAST equalled 8- or 9-points change from baseline using the CGI-S and GAF. One s.e.m. on the FAST corresponded to 7.6-points change from baseline. Cognitive variables insufficiently correlated with anchor variables (all ρ <0.3). One s.e.m. for cognitive variables corresponded to a range of 0.45 to 0.93-s.d. change from baseline.

CONCLUSIONS

These findings support the value of the estimated MCID for the FAST and cognition and may be a useful tool to evaluate cognitive and functional remediation effects and improve patient functional outcomes in BD. The CGI-S and GAF were inappropriate anchors for cognition. Further studies may use performance-based measures of functioning instead.

Neurocognitive Impairment in Bipolar Disorder and Associated Factors: Using Population-based Norms and a Strict Criterion for Impairment Definition

BACKGROUND

Cognitive impairment is often identified in individuals with bipolar disorder and is associated with their functional impairment. However, there is controversy surrounding potential classification methods for impairment in cognitive measures.

OBJECTIVE

To examine the proportion of cognitive measures indicating impairment of attention, processing speed, memory, visuoconstructional abilities, and executive functions in individuals with bipolar disorder type I (euthymic) and healthy controls, using a strict criterion for defining impairment.

METHODS

We gave 43 individuals with bipolar disorder type I and 17 healthy controls a comprehensive clinical and neuropsychological assessment. All scores were standardized using means and standard deviations according to age. Impaired performance in all cognitive measures was determined using a distribution-based threshold of z=±1645. The effects of the sociodemographic and clinical variables on cognitive performance were examined using multiple stepwise backward regression analyses.

RESULTS

Clinically significant cognitive impairment was observed more frequently in the bipolar disorder group, compared to controls, on all measures. From participant factors, we found that level of education and number of manic episodes predicted variation in more cognitive measure scores.

DISCUSSION

The use of population-based norms to standardize cognitive measures, and a strict criterion to define cognitive impairment, in individuals with bipolar disorder type 1 and healthy controls resulted in a prevalence of impairment in cognitive domains' frequencies of deficits that fell within the ranges previously reported in meta-analyses.

CONCLUSIONS

Clinically introducing population norms and a stringent cognitive impairment criterion can facilitate more accurate measures of cognitive impairment in individuals with bipolar disorder.