Age as a predictor of cognitive decline in bipolar disorder

Are subjective language complaints in memory clinic patients informative?

To diagnose mild cognitive impairment, it is crucial to understand whether subjective cognitive complaints reflect objective cognitive deficits. This question has mostly been investigated in the memory domain, with mixed results. Our study was one of the first to address it for language. Participants were 55-to-93-year-old memory clinic patients (n = 163). They filled in a questionnaire about subjective language and memory complaints and performed two language tasks (naming-by-definition and sentence comprehension). Greater language complaints were associated with two language measures, thus showing a moderate value in predicting language performance. Greater relative severity of language versus memory complaints was a better predictor, associated with three language performance measures. Surprisingly, greater memory complaints were associated with better naming, probably due to anosognosia in further disease progression or personality-related factors. Our findings highlight the importance of relative complaint severity across domains and, clinically, call for developing self-assessment questionnaires asking specific questions about multiple cognitive functions.

The emerging neuroimmune hypothesis of bipolar disorder: An updated overview of neuroimmune and microglial findings

Bipolar disorder (BD) is a severe and multifactorial disease, with onset usually in young adulthood, which follows a progressive course throughout life. Replicated epidemiological studies have suggested inflammatory mechanisms and neuroimmune risk factors as primary contributors to the onset and development of BD. While not all patients display overt markers of inflammation, significant evidence suggests that aberrant immune signaling contributes to all stages of the disease and seems to be mood phase dependent, likely explaining the heterogeneity of findings observed in this population. As the brain's immune cells, microglia orchestrate the brain's immune response and play a critical role in maintaining the brain's health across the lifespan. Microglia are also highly sensitive to environmental changes and respond to physiological and pathological events by adapting their functions, structure, and molecular expression. Recently, it has been highlighted that instead of a single population of cells, microglia comprise a heterogeneous community with specialized states adjusted according to the local molecular cues and intercellular interactions. Early evidence has highlighted the contribution of microglia to BD neuropathology, notably for severe outcomes, such as suicidality. However, the roles and diversity of microglial states in this disease are still largely undermined. This review brings an updated overview of current literature on the contribution of neuroimmune risk factors for the onset and progression of BD, the most prominent neuroimmune abnormalities (including biomarker, neuroimaging, ex vivo studies) and the most recent findings of microglial involvement in BD neuropathology. Combining these different shreds of evidence, we aim to propose a unifying hypothesis for BD pathophysiology centered on neuroimmune abnormalities and microglia. Also, we highlight the urgent need to apply novel multi-system biology approaches to characterize the diversity of microglial states and functions involved in this enigmatic disorder, which can open bright perspectives for novel biomarkers and therapeutic discoveries.

Longitudinal changes in resting-state functional connectivity as markers of vulnerability or resilience in first-degree relatives of patients with bipolar disorder

BACKGROUND

There is a significant contribution of genetic factors to the etiology of bipolar disorder (BD). Unaffected first-degree relatives of patients (UR) with BD are at increased risk of developing mental disorders and may manifest cognitive impairments and alterations in brain functional and connective dynamics, akin to their affected relatives.

METHODS

In this prospective longitudinal study, resting-state functional connectivity was used to explore stable and progressive markers of vulnerability i.e. abnormalities shared between UR and BD compared to healthy controls (HC) and resilience i.e. features unique to UR compared to HC and BD in full or partial remission (UR n = 72, mean age = 28.0 ± 7.2 years; HC n = 64, mean age = 30.0 ± 9.7 years; BD patients n = 91, mean age = 30.6 ± 7.7 years). Out of these, 34 UR, 48 BD, and 38 HC were investigated again following a mean time of 1.3 ± 0.4 years.

RESULTS

At baseline, the UR showed lower connectivity values within the default mode network (DMN), frontoparietal network, and the salience network (SN) compared to HC. This connectivity pattern in UR remained stable over the follow-up period and was not present in BD, suggesting a resilience trait. The UR further demonstrated less negative connectivity between the DMN and SN compared to HC, abnormality that remained stable over time and was also present in BD, suggesting a vulnerability marker.

CONCLUSION

Our findings indicate the coexistence of both vulnerability-related abnormalities in resting-state connectivity, as well as adaptive changes possibly promoting resilience to psychopathology in individual at familial risk.

Psychosocial Impairment in Older Patients With Bipolar I Disorder

BACKGROUND

The goal of this study was to assess psychosocial functioning in older patients with bipolar I disorder compared with healthy subjects and to identify the psychopathological factors associated with poor functioning in patients.

METHODS

We recruited 68 euthymic patients with bipolar I disorder from the outpatient unit and 89 healthy controls who were older than 50 years of age. In addition to clinical variables, we used other standardized measures, including the Young Mania Rating Scale, the Hamilton Depression Rating Scale, the Hamilton Anxiety Rating Scale, the Functional Assessment Short Test, and the Montreal Cognitive Assessment.

RESULTS

Older patients with bipolar I disorder had poorer psychosocial functioning in general and in the domains of occupation, autonomy, and cognition than the healthy controls on the basis of previously defined Functional Assessment Short Test cutoff scores. We found that 35.3% (95% CI: 23%-47%) of the patients did not have clinically significant functional impairment, 38.2% (95% CI: 26%-50%) had mild impairment, and 26.5% (95% CI: 16%-37%) had moderate impairment. Depressive symptoms and impaired cognition were associated with poor overall functioning.

CONCLUSIONS

The level of psychosocial functioning was heterogeneous among the patients. Subsyndromal depressive symptoms, even at low levels, and impaired cognition predicted poor functioning in euthymic middle-aged and older patients with bipolar I disorder.

Marked alteration of phosphoinositide signaling-associated molecules in postmortem prefrontal cortex with bipolar disorder

AIM

The etiology of bipolar disorder (BD) remains unknown; however, lipid abnormalities in BD have received increasing attention in recent years. In this study, we examined the expression levels of enzyme proteins associated with the metabolic pathway of phosphoinositides (PIs) and their downstream effectors, protein kinase B (Akt1) and glycogen synthase kinase 3β (GSK3β), which have been assumed to be the targets of mood stabilizers such as lithium, in the postmortem brains of patients with BD.

METHODS

The protein expression levels of phosphatidylinositol 4-phosphate 5-kinase type-1 gamma (PIP5K1C), phosphatidylinositol 4-kinase alpha (PIK4CA), phosphatase and tensin homolog deleted from chromosome 10 (PTEN), Akt1, and GSK3β were measured using enzyme-linked immunosorbent assays and multiplex fluorescent bead-based immunoassays in the prefrontal cortex (PFC). Specifically, PTEN, Akt1, GSK3β, and PIP5K1C were measured in seven BD patients and 48 controls. Additionally, PIK4CA was analyzed in 10 cases and 34 controls.

RESULTS

PTEN expression levels were markedly decreased in the PFCs of patients with BD, whereas those of Akt and GSK3β were prominently elevated. Moreover, patients medicated with lithium exhibited higher Akt1 expression levels and lower PTEN expression levels in comparison with the untreated group.

CONCLUSION

Our results suggest that the expression levels of Akt1/GSK3β and its upstream regulator PTEN are considerably altered.

A cross-sectional study of cognitive performance in bipolar disorder across the lifespan: the cog-BD project

BACKGROUND

Neuroprogressive models of the trajectory of cognitive dysfunction in patients with bipolar disorder (BD) have been proposed. However, few studies have explored the relationships among clinical characteristics of BD, cognitive dysfunction, and aging.

METHODS

We conducted a cross-sectional analysis in euthymic participants with the MATRICS Cognitive Consensus Battery, the Trail Making Test B, the Stroop Test, and the Wechsler Test of Adult Reading. Age- and gender-equated control participants without a mental disorder ['Healthy Controls' - HC)] were assessed similarly. We compared cognitive performance both globally and in seven domains in four groups: younger BD (age ⩽49 years; n = 70), older BD (age ⩾50 years; n = 48), younger HC (n = 153), and older HC (n = 44). We also compared the BD and HC groups using age as a continuous measure. We controlled for relevant covariates and applied a Bonferroni correction.

RESULTS

Our results support both an early impairment ('early hit') model and an accelerated aging model: impairment in attention/vigilance, processing speed, and executive function/working memory were congruent with the accelerated aging hypothesis whereas impairment in verbal memory was congruent with an early impairment model. BD and HC participants exhibited similar age-related decline in reasoning/problem solving and visuospatial memory. There were no age- or diagnosis-related differences in social cognition.

CONCLUSION

Our findings support that different cognitive domains are affected differently by BD and aging. Longitudinal studies are needed to explore trajectories of cognitive performance in BD across the lifespan.

Interactive relationships of Type 2 diabetes and bipolar disorder with cognition: evidence of putative premature cognitive ageing in the UK Biobank Cohort

Type 2 diabetes (T2D) is disproportionately prevalent in bipolar disorder (BD) and is associated with cognitive deficits in psychiatrically healthy cohorts. Whether there is an interaction effect between T2D and BD on cognition remains unclear. Using the UK Biobank, we explored interactions between T2D, BD and cognition during mid and later life; and examined age-related cognitive performance effects in BD as a function of T2D. Data were available for 1511 participants with BD (85 T2D), and 81,162 psychiatrically healthy comparisons (HC) (3430 T2D). BD and T2D status were determined by validated measures created specifically for the UK Biobank. Diagnostic and age-related associations between T2D status and cognition were tested using analyses of covariance or logistic regression. There was a negative association of T2D with visuospatial memory that was specific to BD. Processing speed and prospective memory performance were negatively associated with T2D, irrespective of BD diagnosis. Cognitive deficits were evident in BD patients with T2D compared to those without, with scores either remaining the same (processing speed) or improving (visuospatial memory) as a function of participant age. In contrast, cognitive performance in BD patients without T2D was worse as participant age increased, although the age-related trajectory remained broadly equivalent to the HC group. BD and T2D associated with cognitive performance deficits across the mid-life period; indicating comorbid T2D as a potential risk factor for cognitive dysfunction in BD. In comparison to BD participants without T2D and HCs, age-independent cognitive impairments in BD participants with comorbid T2D suggest a potential premature deterioration of cognitive functioning compared to what would normally be expected.

Aging in bipolar disorder: Cognitive performance and clinical factors based on an adulthood-lifespan perspective

BACKGROUND

The evolution of cognitive performance throughout the lifespan in bipolar disorder (BD) is understudied. This cross-sectional study aims to describe the cognitive performance across age groups.

METHODS

A sample of 654 participants was recruited for this study (BD = 432 and healthy controls -HC- =222). Three subgroups, divided according to age range (18 to 35, 36 to 49, and ≥50 years old) were analyzed after administering a comprehensive neuropsychological battery including six cognitive domains. Demographic, clinical, and psychosocial functioning data were also analyzed. Generalized linear models (GLM) with age, diagnostic group, and age × group as main effects were carried out to examine their potential association on cognitive domains. Subsequently, a GLM in the BD sample was conducted to analyze interactions of several clinical variables by age on each cognitive domain.

RESULTS

Main effects of diagnostic group and age were found in all cognitive domains. Significant group × age effect interaction was found for attention domain (p = 0.02) demonstrating a worse cognitive evolution across age in BD, driven by older age, but not in HC. Significant interaction effects of higher number of manic episodes and older age were also found in attention and verbal memory. Older age was also associated with a longer duration of illness, higher number of episodes, more somatic comorbidities, and poorer psychosocial functioning.

CONCLUSIONS

These results suggest that older age was associated with a selective cognitive decline in BD in the attentional domain. These findings highlight the importance of developing interventions targeting cognitive dysfunction throughout the BD adulthood lifespan.

Data-driven cognitive phenotypes in subjects with bipolar disorder and their clinical markers of severity

BACKGROUND

Subjects with bipolar disorder (BD) show heterogeneous cognitive profile and that not necessarily the disease will lead to unfavorable clinical outcomes. We aimed to identify clinical markers of severity among cognitive clusters in individuals with BD through data-driven methods.

METHODS

We recruited 167 outpatients with BD and 100 unaffected volunteers from Brazil and Spain that underwent a neuropsychological assessment. Cognitive functions assessed were inhibitory control, processing speed, cognitive flexibility, verbal fluency, working memory, short- and long-term verbal memory. We performed hierarchical cluster analysis and discriminant function analysis to determine and confirm cognitive clusters, respectively. Then, we used classification and regression tree (CART) algorithm to determine clinical and sociodemographic variables of the previously defined cognitive clusters.

RESULTS

We identified three neuropsychological subgroups in individuals with BD: intact (35.3%), selectively impaired (34.7%), and severely impaired individuals (29.9%). The most important predictors of cognitive subgroups were years of education, the number of hospitalizations, and age, respectively. The model with CART algorithm showed sensitivity 45.8%, specificity 78.4%, balanced accuracy 62.1%, and the area under the ROC curve was 0.61. Of 10 attributes included in the model, only three variables were able to separate cognitive clusters in BD individuals: years of education, number of hospitalizations, and age.

CONCLUSION

These results corroborate with recent findings of neuropsychological heterogeneity in BD, and suggest an overlapping between premorbid and morbid aspects that influence distinct cognitive courses of the disease.

Cognition in older adults with bipolar disorder: An ISBD task force systematic review and meta-analysis based on a comprehensive neuropsychological assessment

OBJECTIVES

We aim to characterize the cognitive performance in euthymic older adults with bipolar disorder (OABD) through a comprehensive neuropsychological assessment to obtain a detailed neuropsychological profile.

METHODS

We conducted a systematic search in MEDLINE/Pubmed, Cochrane, and PsycInfo databases. Original studies assessing cognitive function in OABD (age ≥50 years ) containing, at a minimum, the domains of attention/processing speed, memory, and executive functions were included. A random-effects meta-analysis was conducted to summarize differences between patients and matched controls in each cognitive domain. We also conducted meta-regressions to estimate the impact of clinical and socio-demographic variables on these differences.

RESULTS

Eight articles, providing data for 328 euthymic OABD patients and 302 healthy controls, were included in the meta-analysis. OABD showed worse performance in comparison with healthy controls, with large significant effect sizes (Hedge's g from -0.77 to -0.89; p < 0.001) in verbal learning and verbal and visual delayed memory. They also displayed statistically significant deficits, with moderate effect size, in processing speed, working memory, immediate memory, cognitive flexibility, verbal fluency, psychomotor function, executive functions, attention, inhibition, and recognition (Hedge's g from -0.52 to -0.76; p < 0.001), but not in language and visuoconstruction domains. None of the examined variables were associated with these deficits.

CONCLUSIONS

Cognitive dysfunction is present in OABD, with important deficits in almost all cognitive domains, especially in the memory domain. Our results highlight the importance of including a routine complete neuropsychological assessment in OABD and also considering therapeutic strategies in OABD.

Identifying neurocognitive heterogeneity in Older Adults with Bipolar Disorder: a cluster analysis

BACKGROUND

Cognitive profiles of BD patients show a demonstrated heterogeneity among young and middle-aged patients, but this issue has not yet deeply explored in Older Adults with bipolar disorder (OABD). The aim of the present study was to analyze cognitive variability in a sample of OABD.

METHODS

A total of 138 OABD patients and 73 healthy controls were included in this study. A comprehensive neuropsychological assessment was administered. We performed a k-means cluster analysis method based on the neurocognitive performance to detect heterogeneous subgroups. Demographic, clinical, cognitive and functional variables were compared. Finally, univariate logistic regressions were conducted to detect variables associated with the severity of the cognitive impairment.

RESULTS

We identified three distinct clusters based on the severity of cognitive impairment: (1) a preserved group (n = 58; 42%) with similar cognitive performance to HC, (2) a group showing mild cognitive deficits in all cognitive domains (n = 64; 46%) and, finally, (3) a group exhibiting severe cognitive impairment (n = 16; 12%). Older age, late onset, higher number of psychiatric admissions and lower psychosocial functioning were associated with the greatest cognitive impairment. Lower age, more years of education and higher estimated IQ were associated with a preserve cognitive functioning.

LIMITATIONS

The small sample size of the severely impaired group.

CONCLUSIONS

Cognitive heterogeneity remains at late-life bipolar disorder. Demographic and specific illness factors are related to cognitive dysfunction. Detecting distinct cognitive subgroups may have significant clinical implications for tailoring specific intervention strategies adapted to the level of the impairment and also to prevent cognitive decline.

Age moderates the relationship between affective response inhibition and bipolar disorder in adults

BACKGROUND

Patients with bipolar disorder (BD) often have impairments in neurocognition, including affective processing and affective response inhibition. While studies suggest that cognitive control in general may decline with age in BD, less is known about age-related changes in response inhibition to emotionally salient information.

METHODS

258 participants with BD and 54 healthy controls, ages 18-70, completed the Cambridge Neuropsychological Test Automated Battery (CANTAB) Affective Go/No-Go task to assess affective response inhibition to positive and negative valenced stimuli. We examined the relationship between BD and affective response inhibition (number of commission and omission errors and reaction time), as well as a potential moderating effect of age, using mixed effects linear regression models.

RESULTS

The BD group made more omission and commission errors overall than the control group (p < 0.018). We observed a significant 3-way group-by-age-by-valence interaction for reaction time (p = 0.006). Within BD, a slower reaction time to negative than positive stimuli was found in middle and older age groups (p < 0.012), but not in the younger age group. No significant moderating effect of age was observed within the control group.

CONCLUSIONS

These cross-sectional findings indicate that compared with healthy controls, individuals with BD display differential and age-related effects in inhibition to emotionally salient information that is valence-dependent. The observed pattern of a switch in bias from negative to positive stimuli with age in BD may aid in our understanding of the progression of neurocognitive changes with aging in BD, as well as inform targeted treatments for cognitive symptoms.

Executive functioning of older adults with bipolar disorder

OBJECTIVES

Despite their impact on daily functioning, we have limited understanding of the executive functioning of older adults with bipolar disorder (OABD). Even less is known about the possible differences in the executive functioning of OABD and older adults with unipolar depression (OADEP).

METHODS

After excluding acutely ill patients, the executive functioning of OABD was compared to that of OADEP and healthy controls (n = 22, n = 20, n = 22; respectively). Cognitive insight, a sub-domain of executive functioning, was operationalized as the discrepancy between the participants' self-reported cognitive functioning and appraisals that were made by their care partners. To complement the cognitive profiling, the groups were compared in information processing speed, verbal memory, and visual-spatial memory.

RESULTS

OABD were impaired in several cognitive domains compared to healthy controls, most prominently in executive functioning and memory. OABD had poorer executive functioning and visual-spatial memory than OADEP. The findings also tentatively point toward intact cognitive insight among OABD, while OADEP seem to have a heightened level of awareness of their cognitive impairment.

CONCLUSIONS

OABD have a unique profile of cognitive impairment compared to OADEP. It is characterized by a more severe cognitive impairment, accompanied by relatively intact cognitive insight. The findings may help clarify the cognitive profile of OABD and assist in the development of cognitive rehabilitation programs tailored to their needs. They should, however, be considered preliminary and await further research.

Comparison of cognitive dysfunction between schizophrenia and bipolar disorder patients: A meta-analysis of comparative studies

OBJECTIVE

Cognitive dysfunction is common in both schizophrenia and bipolar disorder. This is a meta-analysis of studies that compared cognitive dysfunction between schizophrenia and bipolar disorder.

METHODS

Both international and Chinese databases were systematically searched. Studies that compared cognitive function between schizophrenia and bipolar disorder with the MATRICS Consensus Cognitive Battery (MCCB) were analyzed using the random-effects model.

RESULTS

Twelve studies with 9,518 participants (4,411 schizophrenia and 5,107 bipolar patients) were included in the analyses. Schizophrenia patients performed significantly worse than bipolar patients on the MCCB total scores with a large effect size (SMD=-0.80, 95%CI: -1.21 to -0.39), as well as on all the 7 subscale scores; attention (SMD=-2.56, 95%CI: -3.55 to -1.57) and social cognition (SMD=-0.86, 95%CI: -1.13 to -0.58) with large effect sizes; and speed of processing (SMD=-0.75, 95%CI: -1.00 to -0.49), working memory (SMD=-0.68, 95%CI: -0.91 to -0.45), verbal learning (SMD=-0.78, 95%CI: -0.95 to -0.61), visual learning (SMD=-0.65, 95%CI: -0.83 to -0.48), and reasoning and problem solving (SMD=-0.61, 95%CI: -0.93 to -0.29) with medium effect sizes.

CONCLUSION

Compared to bipolar patients, patients with schizophrenia had more severe cognitive dysfunction in this meta-analysis, particularly in attention and social cognition. Timely assessment and treatment of cognitive dysfunction should be part of standard management protocols in both schizophrenia and bipolar disorder.

Accelerated hippocampal biological aging in bipolar disorder

OBJECTIVES

Evidence suggests accelerated aging mechanisms in bipolar disorder (BD), including DNA methylation (DNAm) aging in blood. However, it is unknown whether such mechanisms are also evident in the brain, in particular in association with other biological clocks. To investigate this, we interrogated genome-wide DNAm in postmortem hippocampus from 32 BD-I patients and 32 non-psychiatric controls group-matched for age and sex from the NIMH Human Brain Collection Core.

METHODS

DNAm age and epigenetic aging acceleration were estimated using the Horvath method. Telomere length (TL) and mitochondrial DNA (mtDNA) copy number were quantified by real-time PCR. Between-group differences were assessed by linear regression and univariate general linear models with age, sex, race, postmortem interval, tissue pH, smoking, and body mass index included as co-variates.

RESULTS

Groups did not differ for epigenetic aging acceleration when considering the entire sample. However, after splitting the sample by the median age, an epigenetic aging acceleration was detected in patients compared to controls among older subjects (P = .042). While TL did not differ between groups, a reduction in mtDNA copy number was observed in patients compared to controls (P = .047). In addition, significant correlations were observed between epigenetic aging acceleration and TL (r = -.337, P = .006), as well as between TL and mtDNA copy number (r = .274, P = .028).

CONCLUSIONS

Hippocampal aging may underlie neurocognitive dysfunctions observed in BD patients. Moreover, our results suggest a complex cross-talk between biological clocks in hippocampus that may underlie clinical manifestations of premature aging in BD.

Differences in outcomes between older community-dwelling patients with bipolar disorder and schizophrenia with illness onset at young age

AIM

Older community-dwelling patients with severe mental illness (SMI), particularly those with illness onset at young age, constitute a group of survivors with unique long-term care needs. Using an Asian sample in Taiwan, we attempted to find out the differences in outcomes related to physical health, cognition, and social functioning between older community-dwelling adults with bipolar disorder and schizophrenia with early age onset.

METHODS

Community-dwelling patients aged >50 years with bipolar I disorder or schizophrenia whose illness developed before the age of 40 years were recruited. Clinical data were obtained by reviewing all available medical records and by interviewing the patients and their reliable family members. Medical morbidities, Mini-Mental State Examination (MMSE), Cumulative Illness Rating Scale for Geriatrics (CIRS-G), and Global Assessment of Functioning (GAF) scores were compared between the two groups.

RESULTS

In total, 113 bipolar patients and 104 schizophrenic ones (mean ages = 59.8 and 59.2 years, respectively) became the final subjects. The rates of cognitive impairment (MMSE score <24) were comparable in bipolar disorder (26.5%) and schizophrenia (24.0%) and the mean MMSE scores did not significantly differ from each other. The concurrence (54.9%) of cardiovascular disease (CVD) in the bipolar group was also similar to 51.0% in the schizophrenic one. In a multiple logistic regression analysis, the bipolar group exhibited significantly higher CIRS-G total scores (95% confidence interval (CI) for odds ratio (OR) = 1.01-1.27), body mass index (95% CI for OR = 1.02-1.21), and GAF scores (95% CI for OR = 1.04-1.14).

CONCLUSION

Given better social functioning and the same cognitive function in older community-dwelling patients with bipolar disorder, they may remain at higher risk for obesity and medical morbidity than schizophrenic patients. Treatments targeting cognitive impairment and CVDs across their life span are both necessary to promote the health of community-dwellers with SMI.

Homocysteine, rather than age of onset, is a better predictor for cognitive function in older adults with bipolar disorder

OBJECTIVES

The association between older-age bipolar disorder and cognitive impairments may be mediated by vascular burden. The aim of the study was to examine the difference of cognitive function between older people with late-onset bipolar disorder (LOBD) and early-onset bipolar disorder (EOBD) by considering rigorous vascular risk burden evaluation, comprehensive cognitive tests, and relevant biochemistry data.

METHODS

We recruited 95 outpatients aged over 55 with a DSM-IV-TR diagnosis of bipolar I disorder. Fifty had LOBD, defined by age of onset after 40. Cognitive function was evaluated through a battery of tests assessing verbal memory, attention/speed, visuospatial function, verbal fluency, and cognitive flexibility. Vascular risk assessments included individual disorders, 10-year Framingham cardiovascular risk scores, and serum levels of homocysteine, vitamin B12, folate, and triiodothyronine.

RESULTS

No differences were observed between LOBD and EOBD on any cognitive test after adjusting for potential confounders. In addition to age and educational years, multiple linear regression analyses indicated significantly negative associations between serum homocysteine levels and cognitive performances in attention, psychomotor speed, verbal memory, and executive function.

CONCLUSIONS

Among older people with bipolar disorder, LOBD is not associated with more cognitive dysfunction in this study. However, higher serum homocysteine levels were significantly associated with worse cognitive performance in this particular group. Clinicians therefore have to pay attention to the cognitive function in older bipolar patients with higher levels of homocysteine.

Measurement tools for assessment of older age bipolar disorder: A systematic review of the recent global literature

OBJECTIVES

More than 50% of people with bipolar disorder will be age 60 years or older by 2030. There is a need for more data to guide assessment and treatment in older age bipolar disorder (OABD); however, interpretation of findings from small, single-site studies may not be generalizable and there are few large trials. As a step in the direction of coordinated large-scale OABD data collection, it is critical to identify which measurements are currently used and identify potential gaps in domains typically assessed.

METHODS

An international group of OABD experts performed a systematic literature review to identify studies examining OABD in the past 6 years. Relevant articles were assessed to categorize the types of clinical, cognitive, biomarker, and neuroimaging OABD tools routinely used in OABD studies.

RESULTS

A total of 53 papers were identified, with a broad range of assessments. Most studies evaluated demographic and clinical domains, with fewer studies assessing cognition. There are relatively few biomarker and neuroimaging data, and data collection methods were less comprehensively covered.

CONCLUSION

Assessment tools used in the recent OABD literature may help to identify both a minimum and a comprehensive dataset that should be evaluated in OABD. Our review also highlights gaps where key clinical outcomes have not been routinely assessed. Biomarker and neuroimaging assessment could be further developed and standardized. Clinical data could be combined with neuroimaging, genetic, and other biomarkers in large-scale coordinated data collection to further improve our understanding of OABD phenomenology and biology, thereby contributing to research that advances care.

Increased reward-oriented impulsivity in older bipolar patients: A preliminary study

OBJECTIVE

Impulsivity is a well-established trait of bipolar disorder (BD) that persists across mood phases. It is, however, still unknown whether, in BD, impulsivity remains stable or varies in intensity over the lifespan. This cross-sectional study compared impulsive behavior in older euthymic BD patients and healthy individuals using a range of self-rating and behavioral measures of impulsivity.

METHODS

28 BD patients (56.07 ± 4.08 years, 16 women) and 15 healthy controls (HC; 55.1 ± 3.95 years, 6 women) were administered the Barratt Impulsivity Scale (BIS) and selected tasks of the Cambridge Neuropsychological Test Automated Batter (CANTAB) reflecting impulsivity. Multivariate analysis of variance controlled for age compared impulsivity measures across BD and HC.

RESULTS

BD patients displayed poor decision making, risk taking, and increased delay aversion. Other measures of impulsivity such as response inhibition, sustained cognitive control, and BIS scores were, overall, comparable between BD and HC.

CONCLUSIONS

These preliminary findings suggest that, in BD, aspects of impulsivity related to reward-based decision making persist into late adulthood. Large scale, longitudinal studies are needed to evaluate the relationship of age to impulsivity over time, and explore the link between impulsivity and illness progression in elderly individuals with BD.

The impact of chronic psychiatric disorders on cognitive decline

OBJECTIVES

Based on seemingly contradictory results in the existing literature, the objective of our study was to investigate whether older individuals suffering from chronic psychiatric disorders show a more rapid decline in cognitive performances than their non-psychiatric counterparts, or if the pattern of decline through older age is similar in both groups.

METHOD

A total of 820 older adults were selected from the Ageing Multidisciplinary Investigation (AMI) cohort study, which studies health-related issues of people over 65 years old living in rural areas. Among them, 30 suffer from chronic psychiatric disorders. Cognition was assessed with four neuropsychological tests: the Mini-Mental State Examination, the Digit Symbol Substitution Test, the Free and Cued Selective Reminding test and the Isaacs Set Test. Linear mixed models were used to compare the evolution of cognitive performances in the two groups between baseline and the four-year follow-up.

RESULTS

Despite lower performances at baseline, the pattern of cognitive decline of the psychiatric group is similar to that of the control group.

CONCLUSION

As suggested by this study conducted in rural communities, community-dwelling people suffering from chronic psychiatric disorders should not be considered at greater risk of age-related accelerated cognitive decline than the non-psychiatric older population.

Steeper Slope of Age-Related Changes in White Matter Microstructure and Processing Speed in Bipolar Disorder

OBJECTIVES

Bipolar disorder (BD) is associated with compromised white matter (WM) integrity and deficits in processing speed (PS). Few studies, however, have investigated age relationships with WM structure and cognition to understand possible changes in brain health over the lifespan. This investigation explored whether BD and healthy counterpart (HC) participants exhibited differential age-related associations with WM and cognition, which may be suggestive of accelerated brain and cognitive aging.

DESIGN

Cross-sectional study.

SETTING

University of California San Diego and the Veterans Administration San Diego Healthcare System.

PARTICIPANTS

33 euthymic BD and 38 HC participants.

MEASUREMENTS

Diffusion tensor imaging was acquired as a measure of WM integrity, and tract-specific fractional anisotropy (FA) was extracted utilizing the Johns Hopkins University probability atlas. PS was assessed with the Number and Letter Sequencing conditions of the Delis-Kaplan Executive Function System Trail Making Test.

RESULTS

BD participants demonstrated slower PS compared with the HC group, but no group differences were found in FA across tracts. Multiple linear regressions revealed a significant group-by-age interaction for the right uncinate fasciculus, the left hippocampal portion of the cingulum, and for PS, such that older age was associated with lower FA values and slower PS in the BD group only. The relationship between age and PS did not significantly change after accounting for uncinate FA, suggesting that the observed age associations occur independently.

CONCLUSIONS

Results provide support for future study of the accelerated aging hypothesis by identifying markers of brain health that demonstrate a differential age association in BD.

Bipolar Patients with Vascular Risk Display a Steeper Age-Related Negative Slope in Inhibitory Performance but Not Processing Speed: A Preliminary Study

OBJECTIVE

Bipolar disorder (BD) is associated with cognitive deficits, yet little is known about associations between cognition, vascular risk (VR), and age in this population. This study investigated whether BD patients with VR demonstrate stronger apparent age-related decline in inhibitory performance and processing speed (PS).

METHODS

A full medical history was obtained for 34 euthymic BD and 41 healthy comparison (HC) individuals. The Delis-Kaplan Executive Functions Color Word Interference Subtests were administered to all participants to assess for inhibitory performance (condition 3) and PS (conditions 1 and 2). VR positive (VRPos) and VR negative (VRNeg) groups were created based on the presence of one or more VR factors.

RESULTS

VRPos-BD participants demonstrated significantly worse inhibitory performance with older age, whereas age and inhibition were not significantly related in the VRPos-HC group or in those who were VRNeg. The same was not true for PS.

CONCLUSION

BD patients with VR may also be at risk for greater decline in inhibitory performance, but not PS, with age. Longitudinal studies are needed to further investigate the contributions of VR to cognitive decline among older BD patients.

Neuroprogression and Cognitive Functioning in Bipolar Disorder: A Systematic Review

Bipolar disorder (BD) has been associated with impairments in a range of cognitive domains including attention, verbal learning, and mental flexibility. These deficits are increased during the acute phases of the illness and worsen over the course of BD. This review will examine the literature in relation to potential mechanisms associated with cognitive decline in BD. Scopus (all databases), Pubmed, and Ovid Medline were systematically searched with no language or year restrictions, up to January 2015, for human studies that collected cross-sectional and longitudinal cognitive data in adults with BD and matched healthy controls (HC). Selected search terms were "bipolar," "cognitive," "aging," "illness duration," "onset," and "progression." Thirty-nine studies satisfied the criteria for consideration. There is evidence that cognitive function in BD is negatively associated with features of illness progression such as number of mood episodes, illness duration, and hospitalizations. Aging does not appear to affect cognitive functioning to a greater extent than in HC. Furthermore, the small number of longitudinal studies in this field does not allow to reaching firm conclusion in terms of which sub-populations would be more prone to cognitive decline in BD. The decline in cognitive abilities over the course of the BD seems to be associated with the number of episodes and number of hospitalizations. No meaningful interaction of age and bipolar disorder has been found in terms of cognitive decline. Future large-scale longitudinal studies are necessary to confirm these findings and assist in the development of preventive interventions in vulnerable individuals.