Verbal Memory Impairment in Patients with Subsyndromal Bipolar Disorder

Correlation between low frequency fluctuation and cognitive performance in bipolar disorder patients with suicidal ideation

BACKGROUND

Patients with bipolar disorder (BD) are at high risk of suicidal ideation (SI), and BD patients with suicidal ideation (BDSI) have shown marked abnormalities in spontaneous brain function. Cognitive impairment, on the other hand, is considered to be one of the core symptoms of BD. However, few studies have addressed the association between cognitive performance and abnormal spontaneous brain function in BDSI.

METHODS

In the current study, the MATRICS Consensus Cognitive Battery (MCCB) was used to assess cognitive performance in BDSI (n = 20), BD subjects without suicidal ideation (BDNSI) (n = 24) and healthy controls (HC) (n = 30). Their cognitive performance was then correlated with amplitude of low frequency fluctuation (ALFF) values obtained by resting-state functional magnetic resonance imaging (rs-fMRI).

RESULTS

We found that ALFF was significantly higher in the left precuneus and right posterior cingulate cortex in the BDSI group and significantly lower in the right precuneus in the BDNSI group than in the HC group. In addition, in the BDSI group, visual learning performance was positively correlated with ALFF values in the left precuneus.

CONCLUSIONS

Our findings support the notion that BD patients present with ALFF abnormalities, which are associated with cognitive performance in BDSI.

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.

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

Background

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

Methods

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

Results

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

Conclusions

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

Associations between cognitive impairment and illness awareness in fully remitted bipolar outpatients

The euthymic state of bipolar disorder is often characterized by impaired cognitive function. In this investigation, we hypothesized that subjective cognitive function is impaired and illness awareness is inadequate and we further explored the associations among cognitive complaints, objective cognitive functions, and current illness awareness in Japanese patients. Twenty-seven patients in remission and 27 healthy subjects were recruited in this study. The Japanese version of the Cognitive Complaints in Bipolar Disorder Rating Assessment (COBRA) and Scale to Assess Unawareness in Mental Disorders (Japanese, SUMD-J) were used to assess each patient. All patients underwent neuropsychological tests for the assessment of objective cognitive functions. Only SUMD2.C (current awareness of the effects of medication) was significantly correlated with COBRA, and the objective cognitive assessments, Word Fluency Test and Stroop Test Reaction Time, represented significant correlations with SUMD1.C (current awareness of mental illness). In remitted bipolar outpatients, both the objective and subjective cognitive functions were found to be associated with illness awareness. However, subjective and objective cognitive functions differed in the related illness awareness subscales in fully remitted bipolar outpatients.

Neurocognitive Impairments (NCI) in bipolar disorder: Comparison with schizophrenia and healthy controls

BACKGROUND

Neurocognitive impairments (NCI) are common in patients with bipolar I disorder. However, reports about the affected domains, outcomes and magnitude have been inconsistent. The aim of this study was to compare the magnitude (severity) and specificity (domains), of (NCI) in euthymic Bipolar I Disorder (BD) patients with a demographically and educationally matched sample of patients with schizophrenia in remission (SC) and healthy controls (HC).

METHODS

The Screen for Cognitive Impairment in Psychiatry (SCIP) was applied in this cross-sectional study, to all consecutive and consenting euthymic outpatients with bipolar I disorder (BD) (n = 76), remitted patients with schizophrenia (n = 130) and age and gender-matched healthy controls (HC) (n = 100). The cognitive tests done included Verbal List Learning-Immediate (VLT-I), Working Memory Test (WMT), Verbal Fluency Test (VFT), Verbal Learning Test-Delayed (VLT-D) and Processing Speed Test (PST). Within the bipolar group, the association between NCI and functioning was assessed.

RESULTS

There was a significant difference in the proportions of participants that had cognitive impairment from the 3 groups (37% (HC) vs. 71.1% (BD) vs. 91.5%(SC) (p=<0.001). The BD group in comparison to the HCs did worse on all domains of the SCIP except WMT and PST. The BD group was not significantly different from the SC group in all neuropsychological domains of the SCIP except WMT. BD group significantly functions better than the SC group. The severity of depressive symptomatology and VLT-I were independent predictors of functioning in the BD group.

CONCLUSION

Cognitive impairment affects almost all the neurocognitive domains of the BD group. The difference in NCI between euthymic BD patients and SC in remission are quantitative rather than qualitative.

Associations between cognitive impairment and P300 mean amplitudes in individuals with bipolar disorder in remission

Cognitive functions are often affected during the euthymic state of bipolar disorder (BD). In this study, we investigated the associations among cognitive complaints, objective cognitive functions, and the mean amplitudes of the P300 event-related potential (ERP) wave in individuals with BD. The study population comprised 33 individuals with BD who were in remission and was conducted at Hokkaido University Hospital, Sapporo, Japan. Cognitive complaints were assessed using the Japanese version of the tool named "cognitive complaints in bipolar disorder rating assessment (COBRA)", whereas objective cognitive functions were measured by neuropsychological tests. P300 mean amplitudes were investigated during two- and three-stimulus oddball tasks and showed significant correlations with neuropsychological test scores at all electrode locations, confirming that ERPs and objective cognitive tests that assessed attention and memory function tend to coincide; however, neither P300 amplitudes nor neuropsychological test scores were correlated with COBRA scores. ERPs most likely represent the neurophysiological basis for objective rather than subjective cognitive function in euthymic individuals. Thus, our results suggest that objective cognitive function is related more to P300 mean amplitude scores than subjective cognitive function in individuals with BD.

Insulin resistance is associated with verbal memory impairment in bipolar disorders

BACKGROUND

Cognitive impairment contributes to deterioration in social, family and work functioning in Bipolar Disorder (BD). Cognitive deficits are present not only during, but also outside of mood episodes. Insulin resistance (IR) impairs cognitive functioning and is frequent in participants with BD. Thus, we hypothesized that IR might contribute to cognitive deficits in remitted BD participants.

METHODS

We acquired biochemical (fasting insulin, glucose, lipids) cognitive (California Verbal Learning Test, Digit Span) measures from 100 euthymic participants with BD type I or II. IR was diagnosed using HOMA-IR.

RESULTS

BD participants with IR displayed worse composite verbal memory score (-0.38 vs 0.17; F(1, 8.23)=17.90; p = 0.003), while composite working memory scores were comparable in patients with or without IR (-0.20 vs 0.07; F(1, 6.05)=1.64; p = 0.25). Insulin resistance remained significantly associated with composite verbal memory scores (F(1, 47.99)=9.82, p = 0.003) even when we controlled for levels of lipids. The association between IR and verbal memory was not confounded by exposure to antipsychotics, which were not associated with worse cognitive performance (F(1, 2.07)=5.95, p = 0.13).

LIMITATIONS

The main limitation is the cross-sectional design, which does not allow us to rule out reverse causation.

CONCLUSIONS

We demonstrated that among remitted BD participants without diabetes mellitus, IR was significantly associated with verbal memory performance, even when we controlled for other relevant metabolic or treatment variables. These findings raise the possibility that early detection and treatment of IR, which is reversible, could possibly improve cognitive functioning in at least some BD participants.

The Impact of Subsyndromal Bipolar Symptoms on Patient's Functionality and Quality of Life

Subsyndromal symptoms have rarely been in the focus of bipolar research. This may be, in part, due to the fact that there is neither a uniform definition nor do they constitute an indication of regulatory and commercial interest. Nevertheless, they do have a decisive impact on the long-term course of bipolar disorder (BD), and the degree of functionality and quality of life (QoL) is more likely determined by their presence or absence than by acute episodes. Summarizing the literature an estimated 20-50% of patients suffer inter-episodically or chronically from subsyndromal BD. The most prominent symptoms that interfere with functionality are subsyndromal depression, disturbances of sleep, and perceived cognitive impairment, whereas anxiety negatively impacts on QoL. In the absence of evidence-based pharmacological treatments for subsyndromal BD, clinical practice adopts guidelines designed for treatment-resistant full-blown episodes of BD, supplemented by cognitive-behavioral, family focused or social-rhythm-based psychotherapies.

Social cognition and interaction training (SCIT) for partially remitted patients with bipolar disorder in China

Bipolar disorder (BD) is associated with functional impairment. Social Cognition and Interaction Training (SCIT) has been shown to be feasible and effective at improving social functioning in patients with schizophrenia. We aimed to explore the association between SCIT and improvements in the clinical symptoms and functioning of partially remitted patients with BD in China. Seventy-four BD patients were randomly assigned to the SCIT and psychoeducation (Control) groups. All subjects participated in group interventions weekly for 8 weeks. Furthermore, the participants were administered the Young Mania Rating Scale (YMRS), the 17-item Hamilton Depression Rating Scale (HDRS-17), the Function Assessment Short Test (FAST) and neurocognitive measures at baseline and after eight weeks. There were no differences in demographics, the HDRS-17, YRMS, and FAST scores or neurocognitive measures between the groups at baseline (p>0.05). The repeated-measures analysis revealed that SCIT resulted in greater improvement in the HDRS, YMRS, and FAST scores (including six domains) (p<0.01) and two neurocognitive measures (p<0.05) compared to psychoeducation. Our findings suggest that SCIT is a feasible and promising intervention for the clinical symptoms and functioning of partially remitted patients with BD. Further longitudinal studies are needed to observe the long-term impact of SCIT on emotional and functional improvement in these patients.

Associations between cognitive impairment and quality of life in euthymic bipolar patients

During the euthymic state in bipolar disorder, cognitive functions often remain affected. Specifically, subjective and objective cognitive impairment might distinctly affect patients' quality of life (QoL); however, this question had not been examined previously in Japanese patients. Therefore, the current study investigated the associations between cognitive complaints, QoL, and objective cognitive functions. Forty patients in remission were recruited from the Hokkaido University Hospital, Sapporo, Japan and assessed with the translated version of the cognitive complaints in bipolar disorder rating assessment (COBRA), medical outcomes study 36-item short-form health survey version 2 (SF-36v2), and Sheehan disability scale (SDS). The Japanese adult reading scale, Wisconsin card sorting test, word fluency, continuous performance test, trail making test (TMT), auditory verbal learning, and Stroop test evaluated objective cognitive functions. Significant correlations were observed between the COBRA, SF-36v2, and SDS results, as well as the TMT scores. Overall, euthymic patients were aware of their cognitive dysfunction, which could be understood in relation to the decrease in satisfaction in their daily life. Therefore, even mild cognitive impairments can have ramifications for patients in the euthymic state of bipolar disorder.

Evaluation Of Subjective Cognitive Function Using The Cognitive Complaints In Bipolar Disorder Rating Assessment (COBRA) In Japanese Adults

PURPOSE

To examine the relationship between depressive symptoms, subjective cognitive function, and quality of life in Japanese adults using the Cognitive Complaints in Bipolar Disorder Rating Assessment (COBRA).

PATIENTS AND METHODS

We evaluated 585 adult community volunteers using the Patient Health Questionnaire-9 (PHQ-9) for evaluation of depressive symptoms and the COBRA for evaluation of subjective cognitive function. We additionally used the 8-item Short-Form Health Survey and the Sheehan Disability Scale to evaluate the quality of life (QoL).

RESULTS

Measures of subjective cognitive function were significantly correlated with depressive symptoms and QoL. Structural equation modeling demonstrated that depressive symptoms directly and indirectly decreased QoL via their effects on subjective cognitive dysfunction. Measures of depressive symptoms were more closely related to QoL than were measures of subjective cognitive function.

LIMITATIONS

Study participants were general adult population community volunteers and included healthy people; thus, these results may not be generalizable to patients with depression or bipolar disorder. In addition, the cross-sectional design of this study prevented the identification of causal relationships among the parameters.

CONCLUSION

Changes in subjective cognitive function may affect QoL via depressive symptoms. Evaluations of subjective cognitive function may help identify factors that reduce QoL.