The impact of the trajectory of bipolar disorder on global cognitive function: A one-year clinical prospective case-control study

Evaluation des Troubles Cognitifs Chez des Patients Tunisiens Atteints de Trouble Bipolaire en Rémission : Étude Cas-Témoins: Assessment of Cognitive Impairment in Tunisian Patients With Bipolar Disorder in Remission: A Case-Control Study

OBJECTIVES

Our aims were to assess cognitive impairment in bipolar patients in remission compared with healthy controls, and to study its connection to clinical and therapeutic factors.

METHODOLOGY

This was a case-control study of patients with bipolar disorder (BD) in remission and matched healthy controls. It was carried out at the Hédi Chaker University Hospital in Sfax, Tunisia. The Screen for Cognitive Impairment in Psychiatry (SCIP) scale was used to assess cognitive function in patients and controls. This scale comprises subtests for verbal learning with immediate (VLT-I) and delayed (VLT-D) recall, working memory (WMT), verbal fluency (VFT) and information processing speed (PST).

RESULTS

We recruited 61 patients and 40 controls. Compared with controls, patients had significantly lower scores on the overall SCIP scale and on all SCIP subtests (p < 0.001 throughout) with moderate to high effects. In multivariate analysis, the presence of psychotic characteristics correlated with lower scores on the overall SCIP (p = 0.001), VLT-I (p = 0.001) and VLT-D (p = 0.007), WMT (p = 0.002) and PST (p = 0.008). Bipolar II correlated with lower LTV-I scores (p = 0.023). Age of onset and duration of the disorder were negatively correlated with PST scores (p < 10-3 and p = 0.007, respectively). Predominantly manic polarity correlated with lower VFT scores (p = 0.007).

CONCLUSIONS

Our study showed that bipolar patients in remission presented significantly more marked cognitive impairments, affecting various cognitive domains, than the controls. These cognitive impairments appear to be linked to clinical and therapeutic factors that are themselves considered to be factors of poor prognosis in BD.

Biomarkers for neurodegeneration impact cognitive function: a longitudinal 1-year case-control study of patients with bipolar disorder and healthy control individuals

BACKGROUND

Abnormalities in cerebrospinal fluid (CSF)-amyloid-beta (Aβ)42, CSF-Aβ40, CSF-Aβ38, CSF-soluble amyloid precursor proteins α and β, CSF-total-tau, CSF-phosphorylated-tau, CSF-neurofilament light protein (NF-L), CSF-neurogranin, plasma-Aβ42, plasma-Aβ40, plasma-total-tau, plasma-NF-L and, serum-S100B during affective episodes may reflect brain changes that could impact cognitive function in patients with bipolar disorder (BD). The study aimed to investigate the association between these biomarkers indicative of Alzheimer's disease and those reflecting neurodegeneration alongside their impact on cognitive function in patients with BD and healthy control individuals (HC). The primary hypothesis was that GL and VL would increase with increasing levels of CSF-Aβ42 based on data from T0 and T3 in BD and HC jointly.

METHODS

In a prospective, longitudinal case-control study euthymic patients with BD (N = 85) and HC (N = 44) were evaluated with clinical assessment and neuropsychological testing at baseline (T0) and during euthymia after a year (T3). Patients' affective states were recorded weekly as euthymic, subthreshold level, major depression, or (hypo)mania. If an episode occurred during follow-up, the patient was also assessed in post-episode euthymia. Cognitive performance was measured as a global cognitive score (GL) for four cognitive domains including verbal learning and memory (VL).

RESULTS

Estimated in a linear mixed model GL increased with 0.001 for each increase of 1 pg/ml of CSF-Aβ42 (97.5%, CI 0.00043-0.0018, adjusted-p = 0.0005) while VL increased by 0.00089 (97.5%, CI 0.00015-0.0018, adjusted-p = 0.045) in BD and HC jointly. The association was weak, however stronger in patients with BD compared to HC. Associations between other biomarkers including CSF-neurogranin, and cognitive domains were overall weak, and none remained significant after adjustment for multiple testing.

LIMITATIONS

Modest sample size. A complete data set regarding both CSF-AB-42 and cognitive test scores was obtained from merely 61 patients with BD and 38 HC individuals.

CONCLUSION

CSF-Aβ42 may be associated with cognitive dysfunction in patients with BD and HC individuals. The association appeared to be stronger in BD but with overlapping confidence intervals. Hence it remains uncertain whether the association is a general phenomenon or driven by BD.

Early longitudinal changes in brain structure and cognitive functioning in remitted patients with recently diagnosed bipolar disorder

BACKGROUND

Patients with bipolar disorder (BD) who are presenting with cognitive impairment and associated structural brain abnormalities have generally a poorer clinical outcome. This study aims to map the early longitudinal trajectories in brain structure and cognition in patients with recently diagnosed BD.

METHODS

Fully or partially remitted patients with a recent diagnosis of BD and matched healthy controls (HC) underwent structural MRI and neuropsychological testing at baseline (BD n = 97; HC n = 66) and again following an average of 16 (range 6-27) months (BD n = 50; HC n = 38). We investigated the differential trajectories in BD vs. HC in cortical gray matter volume and thickness, total cerebral white matter, hippocampal and amygdala volumes, estimated brain age, and cognitive functioning using linear mixed models. Within patients, we further investigated whether brain structural abnormalities detected at baseline were associated with subsequent mood episodes.

RESULTS

Compared to HC, patients showed a decline in total white matter volume over time and they had a larger amygdala volume, both at baseline and at follow-up time. Patients further showed lower cognitive performance at both times of investigation with no significant change over time. There were no differences between patients and HC in cortical gray matter volume or thickness, hippocampal volume, or brain-aging patterns.

CONCLUSIONS

Cognitive impairment and amygdala enlargement may represent stable markers of BD early in the course of illness, whereas subtle white matter decline may result from illness progression.

Cerebrospinal fluid erythropoietin, oxidative stress, and cognitive functions in patients with bipolar disorder and healthy control participants: A longitudinal case-control study

Persistent cognitive impairments occur in a large proportion of patients with bipolar disorder (BD) but their underlying pathological cellular processes are unclear. The aims of this longitudinal study of BD and healthy control (HC) participants were to investigate (i) the association of brain erythropoietin (EPO) and oxidative stress with cognitive functions and (ii) the changes in brain EPO during and after affective episodes. Participants underwent neurocognitive testing, lumbar punctures for cerebrospinal fluid (CSF) sampling and provided urine spot tests at baseline (all), after an affective episode (patients) and after one year (all). EPO was assayed in the CSF and oxidative stress metabolites related to RNA and DNA damage (8-dihydroguanosine [8-oxo-Guo], 8-hydroxy-2-deoxyguanosine [8-oxo-dG]) were assayed in the CSF and spot urine. Data was available for analyses for 60 BD and 37 HC participants. In unadjusted primary analyses, verbal memory decreased with increasing concentrations of CSF EPO and oxidative stress. In unadjusted explorative analyses, poorer verbal memory and psychomotor speed were associated with higher levels of oxidative stress. However, no associations between cognitive functions and CSF levels of EPO or oxidative stress were observed after adjustment for multiple testing. CSF EPO concentrations were unchanged during and after affective episodes. While CSF EPO correlated negatively with CSF DNA damage marker 8-oxo-dG, this association rendered non-significant after adjusting for multiple testing. In conclusion, EPO and oxidative stress do not seem to be robustly related to cognitive status in BD. Further insight into the cellular processes involved in cognitive impairments in BD is necessary to pave the way for novel therapeutic strategies to improve patients' cognitive outcomes.

Lifetime and point prevalence of psychotic symptoms in adults with bipolar disorders: a systematic review and meta-analysis

Psychotic symptoms, that we defined as delusions or hallucinations, are common in bipolar disorders (BD). This systematic review and meta-analysis aims to synthesise the literature on both lifetime and point prevalence rates of psychotic symptoms across different BD subtypes, including both BD type I (BDI) and BD type II (BDII). We performed a systematic search of Medline, PsycINFO, Embase and Cochrane Library until 5 August 2021. Fifty-four studies (N = 23 461) of adults with BD met the predefined inclusion criteria for evaluating lifetime prevalence, and 24 studies (N = 6480) for evaluating point prevalence. Quality assessment and assessment of publication bias were performed. Prevalence rates were calculated using random effects meta-analysis, here expressed as percentages with a 95% confidence interval (CI). In studies of at least moderate quality, the pooled lifetime prevalence of psychotic symptoms in BDI was 63% (95% CI 57.5-68) and 22% (95% CI 14-33) in BDII. For BDI inpatients, the pooled lifetime prevalence was 71% (95% CI 61-79). There were no studies of community samples or inpatient BDII. The pooled point prevalence of psychotic symptoms in BDI was 54% (95 CI 41-67). The point prevalence was 57% (95% CI 47-66) in manic episodes and 13% (95% CI 7-23.5) in depressive episodes. There were not enough studies in BDII, BDI depression, mixed episodes and outpatient BDI. The pooled prevalence of psychotic symptoms in BDI may be higher than previously reported. More studies are needed for depressive and mixed episodes and community samples.Prospero registration number: CRD 42017052706.

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.

Differential trajectory of cognitive functions in neurocognitive subgroups of newly diagnosed patients with bipolar disorder and their unaffected first-degree relatives - A longitudinal study

BACKGROUND

Cognitive impairments exist in a large proportion of remitted patients with bipolar disorder (BD). However, no study has investigated the cognitive trajectories across neurocognitive subgroups of patients or their unaffected first-degree relatives (UR).

METHODS

Newly diagnosed BD patients, UR and healthy controls (HC) underwent comprehensive cognitive testing at baseline and at 16-months follow-up. Hierarchical cluster analysis was conducted to identify homogeneous subgroups of patients based on their neurocognitive profile at baseline. Cognitive change across subgroups of patients and UR was assessed with linear mixed-model analyses.

RESULTS

Data from baseline and follow-up were collected from 152 patients, 53 UR and 135 HC. Patients were clustered into three discrete neurocognitive subgroups: 'cognitively normal' (43%), 'mild-moderately impaired' (33%) and 'globally impaired' (24%). While 'mild-moderately impaired' patients and HC showed normative cognitive improvement over time in global cognition (p < .001), 'globally impaired' patients showed greater improvement than all groups (p < .001), whereas 'cognitively normal' patients showed a lack of normative improvement (p = .17). UR of impaired patients showed a lack of normative improvement in executive functions (p = .01). 'Globally impaired' patients also presented with stable impairments in facial expression recognition and emotion regulation.

LIMITATIONS

Follow-up data was available for 62% of participants, possibly reflecting a selection bias.

CONCLUSIONS

The greater cognitive improvement in 'globally impaired' patients partly speaks against neuroprogression. However, the lack of normative improvement in 'cognitively normal' patients could indicate negative effects of illness. Further follow-up assessments are warranted to clarify whether lack of normative improvement in executive function in UR represents an illness risk-marker.

Alzheimer's disease related biomarkers in bipolar disorder - A longitudinal one-year case-control study

INTRODUCTION

Bipolar disorder (BD) is a heterogeneous mental disorder characterized by recurrent relapses of affective episodes: Subgroups of patients with BD have cognitive deficits, and an increased risk of dementia.

METHODS

This prospective, longitudinal, one-year follow-up, case-control study investigated biomarkers for AD and neurodegenerative diseases, namely: cerebrospinal fluid (CSF) amyloid beta (Aβ) isoforms and ratios (Aβ42, Aβ40, Aβ38), CSF soluble amyloid precursor protein (sAPP) α and β, CSF total (t-tau) and phosphorylated tau (p-tau), CSF neurofilament-light (NF-L), CSF neurogranin (NG), plasma-isoforms Aβ42 and Aβ40, plasma-tau, plasma-NF-L, and serum S100B, in patients with BD (N = 62, aged 18-60) and gender-and-age-matched healthy control individuals (N = 40). CSF and plasma/serum samples were collected at baseline, during and after an affective episode, if it occurred, and after a year. Data were analyzed in mixed models.

RESULTS

Levels of CSF Aβ42 decreased in patients with BD who had an episode during follow-up (BD-E) (N = 22) compared to patients without an episode (BD-NE) (N = 25) during follow-up (P = 0.002). Stable levels were seen for all other markers in BD-E compared to BD-NE during the one-year follow-up. We found no statistically significant differences between patients with BD and HC at T0 and T3 for Aβ42, Aβ40, Aβ38, Aβ42/38, Aβ42/40, sAPPα, sAPPβ, t-tau, p-tau, p-tau /t-tau, NF-L, NG in CSF and further Aβ40, Aβ42, Aβ42/40, t-tau, NF-L in plasma, S100B in serum, and APOE-status. Furthermore, all 18 biomarkers were stable in HC during the one-year follow-up from T0 to T3.

CONCLUSION

A panel of biomarkers of Alzheimer's and neurodegeneration show no differences between patients with BD and HC. There were abnormalities of amyloid production/clearance during an acute BD episode. The abnormalities mimic the pattern seen in AD namely decreasing CSF Aβ42 and may suggest an association with brain amyloidosis.

Associations between cognition and subsequent mood episodes in patients with bipolar disorder and their unaffected relatives: A systematic review

BACKGROUND

Bipolar disorder (BD) is highly recurrent and prevention of relapse and illness onset is an urgent treatment priority. This systematic review examined whether cognitive assessments can aid prediction of recurrence in patients with BD and/or illness onset in individuals at familial risk.

METHODS

The review included longitudinal studies of patients with BD or individuals at familial risk of mood disorder that examined the association between cognitive functions and subsequent relapse or illness onset, respectively. We followed the procedures of the Preferred Reporting Items for Systematic reviews and Meta-Analysis (PRISMA) 2020 statement. Searches were conducted on PubMed/MEDLINE, EMBASE and PsychInfo databases from inception up until May 10th 2021.

RESULTS

We identified 19 eligible studies; 12 studies investigated cognitive predictors of recurrence in BD (N = 36-76) and seven investigated cognitive predictors of illness onset in at-risk individuals (N = 84-234). In BD, general cognitive impairment, poorer verbal memory and executive function and positive bias were associated with subsequent (hypo)manic relapse -but with not depressive relapse or mood episodes in general. In first-degree relatives, impairments in attention, verbal memory and executive functions and positive bias were associated with subsequent illness onset.

LIMITATIONS

The findings should be considered preliminary given the small-to-moderate sample sizes and scarcity of studies.

CONCLUSIONS

Subject to replication, the associations between cognitive impairment and (hypo)mania relapse and illness onset may provide a platform for personalised treatment and prophylactic strategies.