The association between sleep and cognitive abnormalities in bipolar disorder

A bibliometric and visual analysis of cognitive function in bipolar disorder from 2012 to 2022

INTRODUCTION

Bipolar disorder (BD) is a chronic psychiatric disorder that combines hypomania or mania and depression. The study aims to investigate the research areas associated with cognitive function in bipolar disorder and identify current research hotspots and frontier areas in this field.

METHODOLOGY

Publications related to cognitive function in BD from 2012 to 2022 were searched on the Web of Science Core Collection (WoSCC) database. VOSviewer, CiteSpace, and Scimago Graphica were used to conduct this bibliometric analysis.

RESULTS

A total of 989 articles on cognitive function in BD were included in this review. These articles were mainly from the United States, China, Canada, Spain and the United Kingdom. Our results showed that the journal "Journal of Affective Disorders" published the most articles. Apart from "Biploar disorder" and "cognitive function", the terms "Schizophrenia", "Meta analysis", "Rating scale" were also the most frequently used keywords. The research on cognitive function in bipolar disorder primarily focused on the following aspects: subgroup, individual, validation and pathophysiology.

CONCLUSIONS

The current concerns and hotspots in the filed are: "neurocognitive impairment", "subgroup", "1st degree relative", "mania", "individual" and "validation". Future research is likely to focus on the following four themes: "Studies of the bipolar disorder and cognitive subgroups", "intra-individual variability", "Validation of cognitive function tool" and "Combined with pathology or other fields".

Relative associations of behavioral and physiological risks for cardiometabolic disease with cognition in bipolar disorder during mid and later-life: findings from the UK biobank

BACKGROUND

Cardiometabolic disease risk factors are disproportionately prevalent in bipolar disorder (BD) and are associated with cognitive impairment. It is, however, unknown which health risk factors for cardiometabolic disease are relevant to cognition in BD. This study aimed to identify the cardiometabolic disease risk factors that are the most important correlates of cognitive impairment in BD; and to examine whether the nature of the relationships vary between mid and later life.

METHODS

Data from the UK Biobank were available for 966 participants with BD, aged between 40 and 69 years. Individual cardiometabolic disease risk factors were initially regressed onto a global cognition score in separate models for the following risk factor domains; (1) health risk behaviors (physical activity, sedentary behavior, smoking, and sleep) and (2) physiological risk factors, stratified into (2a) anthropometric and clinical risk (handgrip strength, body composition, and blood pressure), and (2b) cardiometabolic disease risk biomarkers (CRP, lipid profile, and HbA1c). A final combined multivariate regression model for global cognition was then fitted, including only the predictor variables that were significantly associated with cognition in the previous models.

RESULTS

In the final combined model, lower mentally active and higher passive sedentary behavior, higher levels of physical activity, inadequate sleep duration, higher systolic and lower diastolic blood pressure, and lower handgrip strength were associated with worse global cognition.

CONCLUSIONS

Health risk behaviors, as well as blood pressure and muscular strength, are associated with cognitive function in BD, whereas other traditional physiological cardiometabolic disease risk factors are not.

Processing speed and sustained attention in bipolar disorder and major depressive disorder: A systematic review and meta-analysis

OBJECTIVES

Cognitive impairment is a core feature of bipolar disorder (BD) and major depressive disorder (MDD). Deficits in processing speed (PS) and sustained attention (SA) may be particularly impaired and may underpin a broader profile of deficits, however current knowledge of the nature of these impairments is limited by heterogeneous results in the literature. Few reviews to date have attempted to disentangle sources of heterogeneity to assess the presence and magnitude of impairments in PS and SA in BD and MDD.

METHODS

One hundred and three studies were reviewed to examine performance in tests of PS and SA in BD (n = 3452) and MDD (n = 5461) compared to healthy controls (n = 8016). Neuropsychological methodology used in the literature was summarised. Data were meta-analysed to assess impairments in PS and SA for each neuropsychological test separately. Subgroup analysis was performed across mood states to investigate sources of heterogeneity.

RESULTS

Impairments were found across most neuropsychological tests, with small to large effect sizes for BD (range: d = 0.19-0.96) and MDD (range: d = 0.29-0.86). Impairments were present in symptomatic states and euthymia in most cases. Some outcome measures were not impaired in euthymia. Heterogeneity was observed for most neuropsychological tests and remained after separating by mood state. There inadequate data to meta-analyse some outcome measures, particularly for symptomatic groups.

CONCLUSION

Impairments in PS and SA in BD and MDD can be observed across most neuropsychological tests. Future research should further investigate the nature of these impairments across mood states, controlling for clinical confounds.

Efficacy of spironolactone as adjunctive therapy to sodium valproate in bipolar-I disorder: A double-blind, randomized, placebo-controlled clinical trial

INTRODUCTION

Treatment of mood and cognitive symptoms of patients with bipolar disorder is associated with many complications and is generally not associated with therapeutic satisfaction. In this clinical trial, we evaluated the effectiveness of spironolactone in controlling mood and cognitive symptoms, sleep quality, appetite, and body mass index in patients with bipolar disorder in manic episodes.

METHODS

Sixty inpatients with bipolar disorder in manic episodes were treated with spironolactone/placebo in an 8-week randomized, double-blind, placebo-controlled clinical trial. They were evaluated using the Young Mania Rating Scale (YMRS), mini-mental state examination (MMSE), Pittsburgh sleep quality index, Simplified Nutritional Appetite Questionnaire, and body mass index in weeks 1, 4, and 8.

RESULTS

For cognitive impairment (MMSE), there were significant interaction effects of group and time at week 8 (B = -1.60, SE = 0.69, t = -2.33, p = .021) such that individuals in the spironolactone group experienced more improvement in their cognitive performance. For manic symptoms (YMRS), there were no significant interaction effects of group and time at week 8 (B = -2.53, SE = 1.46, t = -1.73, p = .085).

CONCLUSIONS

Considering the promising findings in this clinical trial, further study of spironolactone as adjunctive therapy in bipolar disorder in manic episodes with larger sample sizes, multicenter settings, and longer follow-ups are recommended.

Enhanced Dynamic Laterality Based on Functional Subnetworks in Patients with Bipolar Disorder

An ocean of studies have pointed to abnormal brain laterality changes in patients with bipolar disorder (BD). Determining the altered brain lateralization will help us to explore the pathogenesis of BD. Our study will fill the gap in the study of the dynamic changes of brain laterality in BD patients and thus provide new insights into BD research. In this work, we used fMRI data from 48 BD patients and 48 normal controls (NC). We constructed the dynamic laterality time series by extracting the dynamic laterality index (DLI) at each sliding window. We then used k-means clustering to partition the laterality states and the Arenas-Fernandez-Gomez (AFG) community detection algorithm to determine the number of states. We characterized subjects' laterality characteristics using the mean laterality index (MLI) and laterality fluctuation (LF). Compared with NC, in all windows and state 1, BD patients showed higher MLI in the attention network (AN) of the right hemisphere, and AN in the left hemisphere showed more frequent laterality fluctuations. AN in the left hemisphere of BD patients showed higher MLI in all windows and state 3 compared to NC. In addition, in the AN of the right hemisphere in state 1, higher MLI in BD patients was significantly associated with patient symptoms. Our study provides new insights into the understanding of BD neuropathology in terms of brain dynamic laterality.

Shared and specific neurobiology in bipolar disorder and unipolar disorder: Evidence based on the connectome gradient and a transcriptome-connectome association study

BACKGROUND

Distinguishing bipolar disorder (BD) and unipolar disorder (UD) remains challenging. To identify the common and diagnosis-specific neuropathological alterations and their potential molecular mechanisms in patients with UD and BD (with a current depressive episode).

METHODS

Resting-state functional magnetic resonance imaging was obtained from 279 participants (95 BD patients, 107 UD patients and 77 health controls). Connectome gradients analysis was performed to explore the shared and diagnosis-specific gradient alterations in BD and UD. The Allen Human Brain Atlas data was used to explore the potential gene mechanisms of the gradient alterations.

RESULTS

BD and UD had shared hierarchical disorganisation, including downgrading and contraction from the unimodal sensory networks (vision and sensorimotor) to the transmodal cognitive networks (limbic, frontoparietal, dorsal attention, and default) (all P < 0.05, FDR corrected) in gradient 1 and gradient 2. The BD patients had specific connectome gradient dysfunction in the subcortical network. Moreover, the hierarchical disorganisation was closely correlated with profiles of gene expression specific to the neuroglial cells in the prefrontal cortex in BD and UD, while the most correlated gene ontology biological processes and function were concentrated in synaptic signalling, calcium ion binding, and transmembrane transporter activity.

CONCLUSION

These findings reveal the shared and diagnosis-specific neurobiological mechanism underlying BD and UD patients, which advances our understanding of the neuromechanisms of these disorders.

The relationship between sleep disturbance and cognitive impairment in mood disorders: A systematic review

BACKGROUND

Cognitive impairment experienced by people with bipolar disorders (BD) or major depressive disorder (MDD) is associated with impaired psychosocial function and poorer quality of life. Sleep disturbance is another core symptom of mood disorders which may be associated with, and perhaps worsen, cognitive impairments. The aim of this systematic review was to critically assess the relationship between sleep disturbance and cognitive impairment in mood disorders.

METHODS

In this systematic review, relevant studies were identified using electronic database searches of PsychINFO, MEDLINE, Embase and Web of Science.

FINDINGS

Fourteen studies were included; eight investigated people with BD, five investigated people with MDD, and one included both people with MDD and people with BD. One study was an intervention for sleep disturbance and the remaining thirteen studies used either a longitudinal or cross-sectional observational design. Ten studies reported a significant association between subjectively measured sleep disturbance and cognitive impairment in people with MDD or BD after adjusting for demographic and clinical covariates, whereas no such association was found in healthy participants. Two studies reported a significant association between objectively measured (actigraphy or polysomnography) sleep abnormalities and cognitive impairment in mood disorders. One study of cognitive behavioural therapy for insomnia modified for BD (CBTI-BD) found an association between improvements in sleep and cognitive performance in BD.

INTERPRETATION

There is preliminary evidence to suggest a significant association between sleep disturbance and cognitive impairment in mood disorders. These findings highlight the need for further research of sleep disturbances and cognitive impairment in people with mood disorders.

The role of anxiety and depressive symptoms in mediating the relationship between subjective sleep quality and cognitive function among older adults in China

BACKGROUND

Deterioration of cognitive function has a significant impact on the unavoidable burden on individuals, families, and society. This study aimed to examine the serial multiple mediating effects of anxiety and depressive symptoms on the relationship between subjective sleep quality and cognitive function among older adults in China.

METHODS

We selected 6442 Chinese older adults aged 65 years and older from the 2018 Chinese Longitudinal Healthy Longevity Survey. The SPSS PROCESS macro was employed to perform simple and serial multiple mediation analyses.

RESULTS

Subjective sleep quality, depressive symptoms, anxiety symptoms, and cognitive function were significantly related (P < 0.01). Poor sleep quality can have a direct negative influence on cognitive function among older adults (effect = -0.110; 95 % CI = [-0.166, -0.053]), but it can also have an indirect negative impact via three pathways: the independent mediation of anxiety symptoms (effect = -0.028; 95 % CI = [-0.048, -0.011]), the independent mediation of depressive symptoms (effect = -0.014; 95 % CI = [-0.026, -0.002]), and the serial mediation of anxiety and depressive symptoms (effect = -0.009; 95 % CI = [-0.017, -0.001]).

LIMITATIONS

This study used a cross-sectional design, which restricts the ability to infer causal relationships.

CONCLUSIONS

The effect of subjective sleep quality on cognitive function was serially mediated by anxiety and depressive symptoms among older adults. Diverse therapies targeted at improving sleep quality in older adults may improve mood and cognitive functioning.

Hypertension, sleep quality, depression, and cognitive function in elderly: A cross-sectional study

Background

Hypertension, sleep disorders, and depression are highly prevalent in the elderly population and are all associated with cognitive impairment, but the role that sleep quality and depression play in the association between hypertension and cognitive impairment is unclear. The aim of this study was to investigate whether sleep quality and depression have a mediating role in the association between hypertension and cognitive impairment.

Methods

A cross-sectional study was conducted to collect data from the Tongji Hospital Comprehensive Geriatric Assessment Database. Sleep quality, depression and cognitive function were measured by the Pittsburgh Sleep Quality Index (PSQI), the Geriatric Depression Scale (GDS-15) and the Mini-Mental State Examination (MMSE), respectively. Correlation analysis, regression analysis and Bootstrap analysis were used to examine correlations between key variables and mediating effects of sleep quality and depression. Adjustments for multiple comparisons were performed using Benjamini-Hochberg adjustment for multiple testing.

Results

A total of 827 participants were included, hypertension was present in 68.3% of the sample. After correcting for covariates, hypertensive patients aged 65 years or older had worse cognitive function, poorer-sleep quality and higher levels of depression. Sleep quality was significantly negatively associated with depression and cognitive function, while depression was negatively associated with cognitive function. Mediation analysis revealed that hypertension can affect cognitive function in older adults through a single mediating effect of sleep quality and depression and a chain mediating effect of sleep quality and depression.

Conclusion

This study found that sleep quality and depression can mediate the relationship between hypertension and cognitive function in elderly. Enhanced supervision of sleep quality and depression in elderly patients with hypertension may be beneficial in maintaining cognitive function.

The effect of exercise on academic fatigue and sleep quality among university students

BACKGROUND

Routine academic events may cause fatigue and impair sleep quality. This research aimed to examine the prevalence and risk factors for academic fatigue among college students and its adverse effects on well-being and sleep. A brief exercise intervention was also evaluated.

METHODS

A total of 864 college students (33.5% female) filled out self-reported questionnaires with few open-ended questions. Fatigue and sleep quality were assessed using the translated version of the Smith Well-being Questionnaire and the Chinese version of the Pittsburgh Sleep Quality Index (PSQI). Spearman correlations, logistic regression analysis, and t-tests were used to test the hypotheses. In a second study, 29 female participants took part in an exercise intervention aimed at reducing fatigue and improving sleep.

RESULTS

Among the effective respondents, nearly 40% reported higher academic-related fatigue, and a few reported high-quality sleep. Negative coping styles, workload, stress, and disturbed surroundings had a significant positive predictive effect on academic fatigue. In addition, adverse consequences of fatigue were found for physical health and academic-life balance, and a significant, positive relationship was observed between the degree of fatigue and PSQI score (p < 0.01). The exercise study showed some beneficial effects of the intervention for both sleep and fatigue outcomes.

CONCLUSION

Fatigue is common and widely reported among Chinese college students, and it may have a major negative impact on their health. Increased awareness of daily academic fatigue and its impact on college students is important for individuals, schools, and society. Exercise may be a simple way to improve sleep and reduce fatigue.

A randomised controlled trial of psychotherapy and cognitive remediation to target cognition in mood disorders

OBJECTIVE

To examine the impact of a treatment package combining Interpersonal and Social Rhythm Therapy (IPSRT) and cognitive remediation (CR), vs IPSRT alone, on cognition, functioning, and mood disturbance outcomes in mood disorders.

METHODS

A pragmatic randomised controlled trial in adults with bipolar disorder (BD) or major depressive disorder (MDD), recently discharged from mental health services in Christchurch, New Zealand, with subjective cognitive difficulties. Individuals were randomised to a 12-month course of IPSRT with CR (IPSRT-CR), or without CR (IPSRT). In IPSRT-CR, CR was incorporated into therapy sessions from approximately session 5 and continued for 12 sessions. The primary outcome was change in Global Cognition (baseline to 12 months).

RESULTS

Sixty-eight individuals (BD n = 26, MDD n = 42; full/partial remission n = 39) were randomised to receive IPSRT-CR or IPSRT (both n = 34). Across treatment arms, individuals received an average of 23 IPSRT sessions. Change in Global Cognition did not differ between arms from baseline to treatment-end (12 months). Psychosocial functioning and longitudinal depression symptoms improved significantly more in the IPSRT compared with IPSRT-CR arm over 12 months, and all measures of functioning and mood symptoms showed moderate effect size differences favouring IPSRT (0.41-0.60). At 18 months, small to moderate, non-significant benefits (0.26-0.47) of IPSRT vs IPSRT-CR were found on functioning and mood outcomes.

CONCLUSIONS

Combining two psychological therapies to target symptomatic and cognitive/functional recovery may reduce the effect of IPSRT, which has implications for treatment planning in clinical practice and for CR trials in mood disorders.

Randomised controlled trial of Interpersonal and Social Rhythm Therapy and group-based Cognitive Remediation versus Interpersonal and Social Rhythm Therapy alone for mood disorders: study protocol

BACKGROUND

Individuals with mood disorders frequently experience cognitive impairment, which impacts on the long-term trajectory of the disorders, including being associated with persisting difficulties in occupational and psychosocial functioning, residual mood symptoms, and relapse. Current first-line treatments for mood disorders do little to improve cognitive function. Targeting cognition in clinical research is thus considered a priority. This protocol outlines a prospectively-registered randomised controlled trial (RCT) which examines the impact of adding group-based Cognitive Remediation (CR) to Interpersonal and Social Rhythm Therapy (IPSRT-CR) for individuals with mood disorders.

METHODS

This is a pragmatic, two-arm, single-blinded RCT comparing IPSRT-CR with IPSRT alone for adults (n = 100) with mood disorders (Major Depressive Disorder or Bipolar Disorder) with subjective cognitive difficulties, on discharge from Specialist Mental Health Services in Christchurch, New Zealand. Both treatment arms will receive a 12-month course of individual IPSRT (full dose = 24 sessions). At 6 months, randomisation to receive, or not, an 8-week group-based CR programme (Action-based Cognitive Remediation - New Zealand) will occur. The primary outcome will be change in Global Cognition between 6 and 12 months (treatment-end) in IPSRT-CR versus IPSRT alone. Secondary outcomes will be change in cognitive, functional, and mood outcomes at 6, 12, 18, and 24 months from baseline and exploratory outcomes include change in quality of life, medication adherence, rumination, and inflammatory markers between treatment arms. Outcome analyses will use an intention-to-treat approach. Sub-group analyses will assess the impact of baseline features on CR treatment response. Participants' experiences of their mood disorder, including treatment, will be examined using qualitative analysis.

DISCUSSION

This will be the first RCT to combine group-based CR with an evidence-based psychotherapy for adults with mood disorders. The trial may provide valuable information regarding how we can help promote long-term recovery from mood disorders. Many issues have been considered in developing this protocol, including: recruitment of the spectrum of mood disorders, screening for cognitive impairment, dose and timing of the CR intervention, choice of comparator treatment, and choice of outcome measures.

TRIAL REGISTRATION

Australian and New Zealand Clinical Trials Registry, ACTRN12619001080112 . Registered on 6 August 2019.

Sex difference in association between insomnia and cognitive impairment in patients with chronic schizophrenia

OBJECTIVE

Sex differences in schizophrenia have been noted across domains such as sleep and cognitive function； however, how they interact remains unclear. This study aimed to explore sex differences in the relationship between insomnia and cognitive function in patients with chronic schizophrenia.

METHODS

718 schizophrenia patients (480 males and 238 females) and 397 healthy controls were recruited. Insomnia was collected by a questionnaire. Insomnia severity index (ISI) was used to evaluate the severity of insomnia. The clinical symptoms and cognition were assessed with the Positive and Negative Syndrome Scale (PANSS) and the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), respectively.

RESULTS

Schizophrenia patients showed significantly lower scores compared to healthy controls on the RBANS total score and four indexes (all p < 0.05). Male patients had a lower rate of insomnia, higher scores on the RBANS visuospatial/constructional, language, and total score than female patients (all P < 0.05). Insomnia patients had lower RBANS immediate memory, language, and total scores than non-insomnia patients, and the results only appeared in female patients (all P < 0.05). In addition, there were significant negative correlations between ISI and RBANS language and delayed memory in male patients, while ISI was significantly negatively correlated with RBANS immediate memory in female patients (all P < 0.05).

CONCLUSION

Our findings suggest that there are sex differences in insomnia, cognitive performance, and their association in patients with chronic schizophrenia. These sex differences may have important potential clinical significance for the identification, evaluation, and treatment of insomnia in patients with chronic schizophrenia.

The relationship between physical activity, BMI, circadian rhythm, and sleep with cognition in bipolar disorder

BACKGROUND

Cognitive deficits affect a significant proportion of patients with bipolar disorder (BD). Problems with sustained attention have been found independent of mood state and the causes are unclear. We aimed to investigate whether physical parameters such as activity levels, sleep, and body mass index (BMI) may be contributing factors.

METHODS

Forty-six patients with BD and 42 controls completed a battery of neuropsychological tests and wore a triaxial accelerometer for 21 days which collected information on physical activity, sleep, and circadian rhythm. Ex-Gaussian analyses were used to characterise reaction time distributions. We used hierarchical regression analyses to examine whether physical activity, BMI, circadian rhythm, and sleep predicted variance in the performance of cognitive tasks.

RESULTS

Neither physical activity, BMI, nor circadian rhythm predicted significant variance on any of the cognitive tasks. However, the presence of a sleep abnormality significantly predicted a higher intra-individual variability of the reaction time distributions on the Attention Network Task.

CONCLUSIONS

This study suggests that there is an association between sleep abnormalities and cognition in BD, with little or no relationship with physical activity, BMI, and circadian rhythm.

Toward a Digital Future in Bipolar Disorder Assessment: A Systematic Review of Disruptions in the Rest-Activity Cycle as Measured by Actigraphy

BACKGROUND

Disruptions in rest and activity patterns are core features of bipolar disorder (BD). However, previous methods have been limited in fully characterizing the patterns. There is still a need to capture dysfunction in daily activity as well as rest patterns in order to more holistically understand the nature of 24-h rhythms in BD. Recent developments in the standardization, processing, and analyses of wearable digital actigraphy devices are advancing longitudinal investigation of rest-activity patterns in real time. The current systematic review aimed to summarize the literature on actigraphy measures of rest-activity patterns in BD to inform the future use of this technology.

METHODS

A comprehensive systematic review using PRISMA guidelines was conducted through PubMed, MEDLINE, PsycINFO, and EMBASE databases, for papers published up to February 2021. Relevant articles utilizing actigraphy measures were extracted and summarized. These papers contributed to three research areas addressed, pertaining to the nature of rest-activity patterns in BD, and the effects of therapeutic interventions on these patterns.

RESULTS

Seventy articles were included. BD was associated with longer sleep onset latency and duration, particularly during depressive episodes and with predictive value for worsening of future manic symptoms. Lower overall daily activity was also associated with BD, especially during depressive episodes, while more variable activity patterns within a day were seen in mania. A small number of studies linked these disruptions with differential patterns of brain functioning and cognitive impairments, as well as more adverse outcomes including increased suicide risk. The stabilizing effect of therapeutic options, including pharmacotherapies and chronotherapies, on activity patterns was supported.

CONCLUSION

The use of actigraphy provides valuable information about rest-activity patterns in BD. Although results suggest that variability in rhythms over time may be a specific feature of BD, definitive conclusions are limited by the small number of studies assessing longitudinal changes over days. Thus, there is an urgent need to extend this work to examine patterns of rhythmicity and regularity in BD. Actigraphy research holds great promise to identify a much-needed specific phenotypic marker for BD that will aid in the development of improved detection, treatment, and prevention options.

Psychological and behavioural interventions in bipolar disorder that target sleep and circadian rhythms: A systematic review of randomised controlled trials

Sleep and circadian disruptions are prominent symptoms of bipolar disorder (BD) and potential targets for adjunctive interventions. The aim of this review was to appraise the effectiveness of psychological and behavioural interventions in BD that target sleep and circadian rhythms, as reported by randomised controlled trials. Nineteen studies met the inclusion/exclusion criteria. They were summarised via narrative synthesis and meta-analysis wherever appropriate. Six studies delivered bright light therapy, five interpersonal and social rhythm therapy, two blue-light blocking glasses, one cognitive behavioural therapy for insomnia, one total sleep deprivation, and four combination treatments. More than half of the studies (N = 10, 52 %) did not measure sleep or circadian rhythms despite being the principal target of the intervention. Overall, the evidence base for the effectiveness of these interventions was limited. There was a small number of studies for each intervention, and a lack of consistency in protocols and outcomes. Meta-analysis was possible for the effect of bright light therapy on depression, revealing a medium-to-large post-treatment effect (Nc = 6; g=-0.74 [95 % CI=-1.05 to -0.42], p < 0.001).

Comparison of objective and subjective sleep parameters in patients with bipolar disorder in both euthymic and residual symptomatic periods

BACKGROUND

Sleep disturbance is a core feature of bipolar disorder; hence, sleep must be accurately assessed in patients with bipolar disorder. Subjective sleep assessment tools such as sleep diary and questionnaires are often used clinically for assessing sleep in these patients. However, the insight into whether these tools are as accurate as objective tools, such as actigraphy, remains controversial.

METHODS

This cross-sectional study included 164 outpatients with a diagnosis of bipolar disorder, including patients who had euthymic and residual symptomatic periods. Objective sleep assessment was conducted prospectively using actigraphy for 7 consecutive days, whereas subjective sleep assessment was conducted prospectively using a sleep diary.

RESULTS

The correlations were high and moderate between sleep diary and actigraphy when assessing the total sleep time and sleep onset latency, respectively (r = 0.81 and 0.47). These correlations remained significant after correction for multiple testing (both p < 0.001) and in both euthymic and residual symptomatic states (total sleep time: r = 0.86 and 0.77; sleep onset latency: r = 0.51 and 0.40, respectively). The median (interquartile ranges) of the percentage difference (sleep diary parameters minus actigraphy parameters divided by actigraphy parameter) in the total sleep time was relatively small (6.2% [-0.2% to 13.6%]).

CONCLUSIONS

Total sleep time assessment using a sleep diary could be clinically useful in the absence of actigraphy or polysomnography.

Bipolar Disorder and Athletes: A Narrative Review

ABSTRACT

Bipolar disorder is a diagnosis with immense lifelong implications that affects 1% to 2% of the general population. It typically presents during late adolescence and early adulthood, which often coincides with the age of peak athletic performance and a limited window of opportunity to compete at the highest levels of sport. Understanding the nature and course of the illness, as well as the effects that pharmacological treatment can have on an athlete, can be extremely beneficial for sports medicine physicians, particularly as many young athletes may not yet be diagnosed and/or adequately treated. Bipolar disorder is an incredibly complex and challenging diagnosis, but the ability to identify symptoms and intervene early is invaluable. The aim of this review is to summarize the available evidence and to highlight relevant risk factors, diagnostic features, management, and potential complications pertaining to the athletic population.

The role of depression and anxiety in the relationship between poor sleep quality and subjective cognitive decline in Chinese elderly: Exploring parallel, serial, and moderated mediation

BACKGROUND

Poor sleep quality exacerbates subjective cognitive decline (SCD). Mental health may play an important role in the relationship, but the potential underlying mechanisms remain unknown.

METHODS

A cross-sectional study was conducted on older adult residents in Guangdong province, south China from November 2020 to March 2021. A total of 717 adults aged 60 years and over were recruited for a face-to-face investigation on a range of socio-demographic factors, lifestyle behaviors, sleep quality, SCD, depressive and anxiety symptoms. Parallel, serial and moderated mediation models were used to examine whether depression and anxiety mediated in the poor sleep quality-SCD linkage.

RESULTS

Both direct and indirect effects of poor sleep quality on SCD symptoms were found. Anxiety and depressive symptoms mediated the relationship between poor sleep quality and SCD symptoms(β_Anxiety = 0.123, 95%CI: 0.079 to 0.173; β_Depression=0.274, 95%CI: 0.200 to 0.348), respectively. Serial mediation analyses indicated that depressive and anxiety symptoms co-play a serial mediating role in the association of poor sleep quality and SCD symptoms (β_a=0.052, 95% CI: 0.026 to 0.084; β_b=0.077, 95% CI: 0.033 to 0.128). Moderated mediation model revealed that the mediation of depressive symptoms on the relationship between poor sleep quality and SCD symptoms was moderated by anxiety symptoms(β=0.318, 95% CI: 0.164 to 0.472).

LIMITATIONS

The study is the cross-sectional design, which limits the causal inference ability.

CONCLUSIONS

These findings provided new insights into possible avenues for prevention and intervention on SCD through sleep-based treatments with a multi-faceted approach on psychiatric disorders.

Cognitive impairment in euthymic patients with bipolar disorder: Prevalence estimation and model selection for predictors of cognitive performance

Objectives Although cognitive dysfunction is a prominent feature of bipolar disorder (BD), previous research presents limitations in estimating the proportion of euthymic patients experiencing clinically relevant deficits and identifying predictors of cognitive difficulties. We explored the relevance of recommended definitions of clinically significant cognitive impairment for functional outcomes, estimated its prevalence, and identified patient characteristics associated with cognition. Methods We assessed cognitive performance across four domains in 80 euthymic participants with BD. Participants were categorized based on two criteria for clinically significant cognitive impairment and we assessed the ability of these criteria to differentiate participant performance on established functional outcomes. Variable selection with elastic net regression was used to identify sociodemographic and clinical factors associated with cognitive performance. Selected variables were examined as predictors of clinically significant cognitive impairment with logistic regression. Results According to the selected criterion, 34% presented with clinically significant cognitive impairment. Poorer current cognitive performance was associated with older age, lower estimated premorbid IQ, more currently prescribed psychotropic medications, fewer previous psychological therapies, and current use of antipsychotics. A model with premorbid IQ, psychotropic medications and previous psychological therapies as predictors of cognitive impairment correctly classified 75% of the participants. Conclusions This is one of the first studies to use a model selection approach to identify factors associated with cognitive difficulties in BD. Our findings offer the initial steps towards a predictive model for cognitive impairment. This could improve treatment decisions and prioritization for euthymic patients with BD, particularly the implementation of cognitive interventions.

The effect of concomitant benzodiazepine use on neurocognition in stable, long-term patients with bipolar disorder

OBJECTIVE

Neurocognitive dysfunction is a common feature of bipolar disorder even in euthymia, and psychopharmacological treatment could have an effect on cognition. Long-term prescription of benzodiazepines in bipolar disorder is a common practice, and their effect on neurocognition has not been well studied in this population. The aim of this study was to evaluate the impact of concomitant benzodiazepine long-term use on neurocognitive function in stable euthymic bipolar disorder patients.

METHODS

Seventy-three euthymic bipolar disorder outpatients and 40 healthy individuals were assessed using a neurocognitive battery. Patients were classified in two groups according to the presence of benzodiazepines in their treatment: the benzodiazepine group (n = 34) and the non- benzodiazepine group (n = 39). Neurocognitive performance was compared between the groups using a multivariate analysis of covariance, considering age, number of depressive episodes, adjuvant antipsychotic drugs, Young Mania Rating Scale score and Hamilton Depression Rating Scale score as covariates.

RESULTS

Both bipolar disorder groups (benzodiazepine and non-benzodiazepine) showed an impairment in memory domains (Immediate Visual Memory [p = 0.013], Working Memory [p < 0.001], and Letter-Number Sequence [p < 0.001] from the Wechsler Memory Scale-Revised-III) and slower processing speed functions (Stroop Colour [p < 0.001]) relative to the control group. Nevertheless, the benzodiazepine group showed a greater impairment in executive functions (Conceptual Level Responses [p = 0.024] from the Wisconsin Card Sorting Test and Frontal Assessment Battery [p = 0.042]).

CONCLUSION

Although memory and processing speed impairments were found in bipolar disorder, regardless of their benzodiazepine treatment, benzodiazepine users presented additional neurocognitive impairments in terms of executive functioning. These findings support restricted prescription of benzodiazepines in individuals with bipolar disorder.

Sleep quality and neuropsychological functioning in bipolar I disorder

BACKGROUND

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

METHODS

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

RESULTS

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

LIMITATIONS

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

CONCLUSIONS

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

Correlates of poor sleep based upon wrist actigraphy data in bipolar disorder

BACKGROUND

Wrist-worn actigraphy can objectively measure sleep, and has advantages over self-report, particularly for people with Bipolar Disorder (BD) for whom self-reports might be influenced by affect. Clinically useful data reduction approaches are needed to explore these complex data.

METHODS

We created a composite score of sleep metrics in BD based on 51 BD and 80 healthy comparison (HC) participants. Subjects wore an actigraph for up to 14 consecutive 24-h periods, and we assessed total sleep time (TST), wake after sleep onset (WASO), percent sleep (PS), and number of awakenings (NA). We focused on participants who had at least 5 nights of actigraphy data. We computed z-scores for within-person means of sleep measures for BD subjects versus HCs, which were averaged to create a composite measure. We correlated this composite with participant characteristics, and used LASSO regression to identify sleep measures best explaining variability in identified correlates.

RESULTS

Sleep measures and the composite did not differ between BDs and HCs; however, there was considerable variability in z-scores among those with BD. In BDs, the composite score was higher in women (t₍₄₉₎ = 2.28, p = 0.027) and those who were employed (t₍₃₄₎ = 2.34, p = 0.025), and positively correlated with medication load (r = 0.41, p = 0.003) while negatively correlated with Young Mania Rating Scale (YMRS; r = -0.35, p = 0.030). In LASSO regression, TST and NA best explained medication load while PS best explained employment and YMRS.

CONCLUSION

While a composite score of sleep metrics may provide useful information about sleep quality globally, our findings suggest that selection of theory-driven sleep measures may be more clinically meaningful.

Effect of evening light exposure on sleep in bipolar disorder: A longitudinal analysis for repeated measures in the APPLE cohort

OBJECTIVE

Sleep disturbance, a core feature of bipolar disorder, is associated with residual mood symptoms, mood episode recurrence and suicide ideation. We investigated the effect of evening light exposure on sleep in patients with bipolar disorder.

METHODS

In this longitudinal analysis, we measured the sleep parameters of 207 outpatients with bipolar disorder using actigraphy at their homes for seven consecutive nights. We measured the white-light illuminance and the irradiance of each wavelength during the 4 hours before each participant's bedtime. We used mixed-effect linear regression analysis for repeated measures to evaluate the effect of evening light exposure on subsequent sleep parameters.

RESULTS

The median white-light illuminance was 25.8 lux (interquartile range, 12.9-50.1 lux). In a multivariable model adjusted for potential confounders, we found higher white-light illuminance to be significantly associated with lower sleep efficiency (per log lux: 95% confidence interval = [-1.328, -0.133]; p = 0.017), prolonged sleep-onset latency (95% confidence interval = [0.006, 0.172]; p = 0.035) and longer wake after sleep onset (95% confidence interval = [1.104, 4.459]; p = 0.001). This effect size was larger in the younger age group (aged < 44 years) stratified by median age. Higher irradiance of the blue wavelength range was significantly associated with longer wake after sleep onset, a result similar to those for the green and red wavelength ranges.

CONCLUSION

We observed significant associations between evening light exposure and subsequent sleep in patients with bipolar disorder. The effects of various light wavelengths on sleep in bipolar disorder require further investigation.

"Influence of modifiable and non-modifiable variables on functioning in bipolar disorder: a path analytical study"

OBJECTIVE

The aim of this study was to investigate the influence of modifiable (mood, cognitive reserve, cognitive performance) and non-modifiable factors (diagnosis, suicide attempts, substance use, age) on self-reported functioning in BD.

METHODS

103 adults with no mood disorders and 95 individuals with BD completed the WHODAS 2.0, in addition to a neuropsychological battery and diagnostic assessments. Path analysis was then used to analyse the relationships between modifiable and non-modifiable predictors of functioning in the sample.

RESULTS

Cognitive reserve and age had an indirect influence on individual functioning, mediated by cognitive performance. The influence of diagnosis and depressive symptoms on functioning was partly direct, and partly mediated by cognition. The presence of psychiatric comorbidities in addition to BD also had a significant influence on individual functioning.

CONCLUSIONS

Initiatives focussed on modifiable factors such as depressive symptoms and cognitively stimulating activities, which increase cognitive reserve, may be a useful complement to existing treatments and help patients achieve functional recovery. KEY POINTS Individual functioning was influenced by cognitive performance, cognitive reserve, age, diagnosis and depressive symptoms. Executive functioning mediated the influence of age and cognitive reserve on individual functioning. Interventions focussed on depressive symptoms and cognitive stimulation may help patients achieve functional recovery.

Do sleep disturbances contribute to cognitive impairments in schizophrenia spectrum and bipolar disorders?

Sleep disturbances and cognitive impairments are both frequent across psychotic disorders, with debilitating effects on functioning and quality of life. This study aims to investigate if sleep disturbances are related to cognitive impairments in schizophrenia spectrum (SCZ) and bipolar disorders (BD), if this relationship varies between different sleep disturbances (insomnia, hypersomnia or delayed sleep phase (DSP)) and lastly, if this relationship differs between clinical groups and healthy controls (HC). We included 797 patients (SCZ = 457, BD = 340) from the Norwegian Centre for Mental Disorders Research (NORMENT) study in Norway. Sleep disturbances were based on items from the Inventory of Depressive Symptoms-Clinician rated scale (IDS-C). Their relationship with several cognitive domains was tested using separate ANCOVAs. A three-way between-groups ANOVA was conducted to test if the relationship with cognitive impairments varies between different sleep disturbances. These analyses revealed significantly poorer processing speed and inhibition in those with any sleep disturbance versus those without, also after adjusting for several covariates. The relationship between sleep disturbances and cognition was similar across SCZ and BD, and there were significant effects of insomnia and hypersomnia on both processing speed and inhibition. No association between sleep disturbances and cognition was found in HC. Sleep disturbances contribute to cognitive impairments in psychotic disorders. Processing speed and inhibition is poorer in patients with sleep disturbances. Impairments in these domains are related to insomnia and hypersomnia. These findings suggest that treating sleep disturbances is important to protect cognitive functioning, alongside cognitive remediation in psychotic disorders.

Neuropsychology of Bipolar Disorder

Bipolar disorder is associated with significant dysfunction in a broad range of neuropsychological domains and processes. Deficits have been reported to occur in symptomatic states (depression, [hypo]mania) as well as in remission (euthymia), having consequences for psychological well-being and social and occupational functioning. The profile and magnitude of neuropsychological deficits in bipolar disorder have been explored in a number of systematic reviews and meta-analyses. After discussing these briefly, this chapter will focus on examining the clinical and demographic factors that influence and modify the pattern and magnitude of deficits, as well as reviewing methods of assessment and analysis approaches which may improve our understanding of these problems.

[Relationship between circadian rhythm related brain dysfunction and bipolar disorder]

OBJECTIVE

To investigate the changes of functional connectivity (FC) in the suprachiasmatic nucleus (SCN) of patients with bipolar disorder and perform a cluster analysis of patients with bipolar disorder based on FC.

METHODS

The study recruited 138 patients with bipolar disorder (BD) diagnosed according to the 4th edition of Diagnostic and Statistical Manual of Mental Disorders IV (DSM-IV) and 150 healthy control subjects. All the participants underwent resting-state functional magnetic resonance brain scans. DPARSF software was used to generate the FC diagram of the SCN. Based on the FC data, principal components analysis (PCA) and k-means in scikit-learn 0.20.1 were used for cluster analysis of the patients with bipolar disorder.

RESULTS

Compared with the healthy controls, the patients showed enhanced functional connections between the SCN and the paraventricular nucleus and between the SCN and the dorsomedial hypothalamus nucleus. Based on these FC values, the optimal cluster of unsupervised k-means machine learning for bipolar disorder was 2, and the Silhouette coefficient was 0.49.

CONCLUSIONS

Patients with bipolar disorder have changes in the FC of the SCN, and the FC of the rhythm pathway can divide bipolar disorder into two subtypes, suggesting that biological rhythm is one of the potential biomarkers of bipolar disorder.