Similar profiles of cognitive domain deficits between medication-naïve patients with bipolar II depression and those with major depressive disorder

Differences in cognitive deficits and brain functional impairments between patients with first-episode and recurrent depression

BACKGROUND

Accumulating evidence shows that cognitive deficits are common in patients with major depressive disorder (MDD). However, the specific differences in cognitive impairment and brain functional alterations between first-episode depression (FED) and recurrent major depression (RMD) remain unclear, as do the relationships among these factors.

METHODS

A total of 43 RMD and 41 FED patients were included in this study. All the patients underwent examinations of resting-state functional magnetic resonance imaging (fMRI), event-related potential (ERP) measurements, and a series of standardised neuropsychological tests, including event-based (EBPM) and time-based (TBPM) prospective memory tasks, the Semantic Fluency Test (SFT), and the Continuous Performance Task-Identical Pairs (CPT-IP). Two-sample t-tests were used to compare cognitive functioning, ERP parameters, and brain functional indices between FED and RMD groups. Correlation analyses were performed to explore the associations between these variables.

RESULTS

Compared with FED patients, those with RMD displayed poorer CPT-IP performance, lower prospective memory (EBPM) scores, lower SFT performance, and prolonged P300 latency (all P < 0.05). Moreover, neuroimaging data analysis revealed increased regional neural activity in the right inferior temporal gyrus (ITG), alongside decreased interhemispheric functional connectivity in the bilateral ITG in RMD relative to FED. Correlation analyses indicated that these functional changes were significantly associated with the observed cognitive deficits.

CONCLUSION

Our data demonstrated more pronounced cognitive deficits and brain functional impairments in RMD relative to FED as well as their potential links. These findings not only elucidate the neural mechanisms underlying cognitive deficits in MDD, but also inform future treatment and prevention of cognitive dysfunction in patients suffering from MDD.

CLINICAL TRIAL NUMBER

Not applicable.

Computational cognitive mechanisms of visual working memory in major depressive disorder and sex differences

This study examined the computational cognitive mechanisms of visual working memory (VWM) in MDD, focusing on memory precision while exploring potential sex differences. 159 Major Depressive Disorder (MDD) patients and 67 healthy controls (HC) completed the color delay estimation task to measure their VWM. The mainstream models of VWM were compared, and the variable-precision (VP) model was the best fit for our data. The Bayesian ANCOVA was used to compare the differences between groups (MDD & HC) and sexes (male & female). Results revealed that MDD had worse memory precision than HC (BF10 = 103.872, decisive evidence for H1). Specifically, they had larger resource allocation variability (BF10 = 19.421, strong evidence for H1), indicating that they distributed memory resources more unevenly across different items than HC. In addition, females had better memory precision than males (BF10 = 10.548, strong evidence for H1). More specifically, they had more initial resources during the color delay estimation task (BF10 = 6.003, substantial evidence for H1) than males. These findings highlight the critical role of diminished precision, specifically, larger resource allocation variability, in impaired VWM in MDD. Meanwhile, these findings highlight sex differences in memory precision and initial resources of VWM.

Using the THINC-integrated tool to compare the characteristics of cognitive dysfunction in patients with unipolar and bipolar depression

BACKGROUND

Major depressive disorder (MDD) and bipolar depression (BD-D) are both intricate, enduring, and profound psychiatric conditions characterized primarily by depressive episodes and cognitive dysfunction. However, distinguishing the characteristics and influencing factors of cognitive impairment in unipolar and BD-D is crucial for identification and intervention.

AIM

To compare neurocognitive characteristics and investigate associations between cognitive function and clinical features in unipolar and BD-D.

METHODS

The THINC-integrated tool (THINC-it) as a cognitive assessment tool was applied to 295 individuals: 75 patients with depressive disorders (MDD), 120 individuals with BD-D, and 100 healthy controls. The Hamilton Depression Scale-17 (HAMD), Hamilton Anxiety Scale-14 (HAMA), and Pittsburgh Sleep Quality Index (PSQI) were employed to assess depression, anxiety, and sleep. Neurocognitive function characteristics and the relationships between cognitive impairment and general clinical attributes were analyzed.

RESULTS

There were no statistically significant differences in the overall THINC-it with each objective subscale. However, the subjective subscale (Perceived Deficits Questionnaire for Depression-5-item) showed significant differences between MDD and BD-D (P < 0.001). Linear regression analyses were explored to determine associations. Age, years of education, age at onset, and HAMD were significantly co-associated with the overall THINC-it and each subscale in both MDD and BD-D (P < 0.05). Furthermore, years of education showed a positive correlation with objective cognitive impairment (e.g., Codebreaker, Trails) (P < 0.05). There was a notable difference in that the number of depressive episodes, disease duration, hospitalizations, HAMA, and PSQI were significantly associated with the overall THINC-it with each subscale between MDD and BD-D (P < 0.05).

CONCLUSION

Although both unipolar and BD-D showed similar objective cognitive impairments, there was a significant difference in subjective cognitive impairment. Our findings suggest that factors like age, years of education, age at onset, and depression severity might not be significantly difference in the influence of cognitive impairment. Furthermore, we found that education was a protective factor for cognitive impairment in both unipolar and BD-D. Our analysis revealed that distinct factors including disease duration, number of depressive episodes, hospitalizations, anxiety levels, and sleep quality influenced cognitive impairment between unipolar and BD-D. Therefore, it was important to investigate the specific characteristics of cognitive impairment and influencing factors to identify differentiating unipolar and BD-D.

Differences in cognitive impairment and its correlation with circulating cell-free mitochondrial DNA in medication-free depression and bipolar depression patients

OBJECTIVE

This study aimed to investigate whether there are differences in cognitive impairment between medication-free patients with bipolar depression (BD) and major depressive disorder (MDD) and whether these differences are related to circulating cell-free mtDNA (ccf-mtDNA).

METHODS

For this cross-sectional study, 76 outpatients with BD, 86 outpatients with MDD and 70 healthy controls (HCs) were enrolled. Sociodemographic and clinical data were collected. The Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) and the Stroop Color-Word Test were used to assess cognitive function. Plasma ccf-mtDNA levels were measured via qPCR.

RESULTS

BD and MDD patients had similar scores for immediate memory, language, attention, delayed memory, the RBANS total score, Stroop color, Stroop word, and Stroop total score, which were significantly lower than the HCs. The visuospatial/constructive scores of the BD patients were significantly lower than those of the HCs (p < 0.001) and MDD patients (p = 0.008), but there was no difference between the HCs and MDD patients. The ccf-mtDNA levels in the BD and MDD patient groups were significantly higher than those in the HC group, and those in the MDD group were higher than those in the BD group (p = 0.016). Multiple stepwise regression analysis showed that ccf-mtDNA was negatively correlated with language in patients with depression (t = -2.11, p = 0.039).

CONCLUSION

There were differences in specific cognitive dimensions between patients with BD and MDD. Increased ccf-mtDNA levels were found in BD and MDD patients, suggesting ccf-mtDNA may be involved in the pathophysiology of MDD and BD.

Comparison of cognitive performance in first-episode drug-naïve schizophrenia, bipolar II disorder, and major depressive disorder patients after treatment

BACKGROUND

Cognitive impairment is a recognized fundamental deficit in individuals diagnosed with schizophrenia (SZ), bipolar II disorder (BD II), and major depressive disorder (MDD), among other psychiatric disorders. However, limited research has compared cognitive function among first-episode drug-naïve individuals with SZ, BD II, or MDD.

METHODS

This study aimed to address this gap by assessing the cognitive performance of 235 participants (40 healthy controls, 58 SZ patients, 72 BD II patients, and 65 MDD patients) using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) before and after 12 weeks of treatment in SZ, BD II, and MDD patients. To clarify, the healthy controls only underwent RBANS testing at baseline, whereas the patient groups were assessed before and after treatment. The severity of symptoms in SZ patients was measured using the Positive and Negative Syndrome Scale (PANSS), and depression in BD II and MDD patients was assessed using the Hamilton Depression Scale-24 items (HAMD-24 items).

RESULTS

Two hundred participants completed the 12-week treatment period, with 35 participants dropping out due to various reasons. This group included 49 SZ patients, 58 BD II patients, and 53 MDD patients. Among SZ patients, significant improvements in immediate and delayed memory were observed after 12 weeks of treatment compared to their initial scores. Similarly, BD II patients showed significant improvement in immediate and delayed memory following treatment. However, there were no significant differences in RBANS scores for MDD patients after 12 weeks of treatment.

CONCLUSIONS

In conclusion, the findings of this study suggest that individuals with BD II and SZ may share similar deficits in cognitive domains. It is important to note that standardized clinical treatment may have varying degrees of effectiveness in improving cognitive function in patients with BD II and SZ, which could potentially alleviate cognitive dysfunction.

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.

Cognitive performance in depression in low- and middle-income countries: A systematic review with meta-analytic components

BACKGROUND

Depression is highly prevalent in low- and middle- income countries (LMIC) and associated with significant cognitive dysfunction across multiple domains. However, little is known about neurocognitive tests used in people with depression in LMIC. We aimed to investigate cognitive performance and cognitive tests in depression research in LMIC.

METHODS

APA PsycInfo, Embase, Ovid MEDLINE, and Global Health were systematically searched for studies that implemented a cognitive performance test in a depressed, LMIC population. Tool quality was assessed using an adapted scale for quality of measures in cross-cultural settings. Data extracted included demographics, depression and cognitive performance measures, and cognitive performance comparisons between depression and control groups.

RESULTS

29 studies met eligibility criteria, involving a total of 19,100 participants from 11 LMIC. 93.1 % of studies were conducted in upper middle-income countries. 67 cognitive performance tools were implemented. Reliability was reported for 5.6 % of cognitive performance tests and validity was reported for 8.3 %. 36.1 % of tests used were culturally adapted. 75.9 % of included studies implemented at least one memory test. Cognitive deficits were observed in all depressed groups, especially in memory (Cohen's d = -1.60, 95 % CI -2.02 to -1.18).

LIMITATIONS

Heterogeneity between studies; averaged results across memory subtypes; no assessment of depression severity and cognitive deficits associations; restrictive search terms.

CONCLUSIONS

Cognitive impairments in depression, especially in memory, are prevalent in LMIC. This research has drawn attention to the burden of cognitive dysfunction in depression in LMIC, and to the disparate research gap in LMIC. PROSPERO registration CRD42022315397.

Convergent and divergent cognitive impairment of unipolar and bipolar depression: A magnetoencephalography resting-state study

BACKGROUND

Unipolar depression (UD) and bipolar depression (BD) showed convergent and divergent cognitive impairments. Neural oscillations are linked to the foundational cognitive processes. We aimed to investigate the underpinning spectral neuronal power patterns by magnetoencephalography (MEG), which combinates high spatial and temporal resolution. We hypothesized that patients with UD and BD exhibit common and distinct patterns, which may contribute to their cognitive impairments.

METHODS

Group cognitive tests were performed. Eyes closed resting-state MEG data were collected from 61 UD, 55 BD, and 52 healthy controls (HC). Nonparametric cluster-based permutation tests were performed to deal with the multiple comparison problem on channel-frequency MEG data. Correlation analysis of cognitive dysfunction scores and MEG oscillation were conducted by Spearman or partial correlation analysis.

RESULTS

Wisconsin Card Sorting Test showed similar cognitive impairment in patients with UD and BD. Moreover, patients with BD exhibited extensive cognitive deficits in verbal executive functions and visuospatial processing. Compare to HC, both patients with UD and BD showed increased frontal-central beta power while high gamma power was decreased in UD groups during the resting-state. The significant correlations between cognitive function and average beta power were observed.

CONCLUSIONS

Patients with BD had more cognitive impairments on different dimensions than those with UD, involving disrupted beta power modulations. Our investigation provides a better understanding of the neuroelectrophysiological process underlying cognitive impairments in patients with UD and BD.

Effects of virtual reality working memory training on event-based prospective memory in patients with major depressive disorder

BACKGROUND

Event-based prospective memory (EBPM) refers to remembering to perform delayed intention when specific events occur. EBPM deficit is present in patients with major depressive disorder (MDD) and hinders recovery from the illness. Working memory training (WMT) has been reported to enhance EBPM but its effect on EBPM in MDD remains unclear. We investigated whether virtual reality (VR)-based WMT can improve EBPM in MDD patients.

METHODS

Forty-six MDD patients and 41 healthy controls (HC) were recruited. Among the former ones, the first 23 consecutive patients were allocated to the experimental group (MDD-VR) and the next 23 consecutive patients to the waitlist control group (MDD-W). EBPM accuracy was used to assess EBPM performance. Hamilton Depression Rating Scale (HDRS) and Massachusetts General Hospital Cognitive and Physical Functioning Questionnaire (CPFQ) were employed to assess the cognitive functions and the depressive symptoms.

RESULTS

At baseline, EBPM accuracy did not significantly differ between MDD-VR and MDD-W but was lower in both of these two groups than in HC (both p < 0.001). Group-by-time interactions on EBPM accuracy (F = 4.614, p = 0.031) and CPFQ score (F = 5.754, p = 0.021) were present, whereas no significant group-by-time interaction or group effects were observed for HDRS score (both p > 0.05). After VR intervention, MDD-VR showed an increase in EBPM accuracy (Cohen's d = 1.20 [95% CI: 0.53, 1.86], p = 0.001).

CONCLUSIONS

Our results demonstrated that VR-based WMT could improve EBPM deficits in MDD patients. Large-scale studies of a VR-based WMT program are indicated.

The association between overweight/obesity and poor cognitive function is mediated by inflammation in patients with major depressive disorder

BACKGROUND

Cognitive dysfunction is a common and core feature of major depressive disorder (MDD). Evidences exerted a potentially harmful role of obesity and higher peripheral levels of inflammation in cognitive function, but few studies have explored whether markers of peripheral inflammation might mediate the association between overweight/obesity and deficits in cognitive function. Our study aimed to examine the cognitive function in MDD patients and clarify the effects of overweight/obesity and inflammatory cytokines on cognitive dysfunction in this population.

METHOD

We used a cross-sectional design in this study. A total of 265 patients with MDD were enrolled and divided into underweight, normal weight and overweight/obese groups. The MATRICS Consensus Cognitive Battery (MCCB) was administered to measure the cognition. Plasma levels of nineteen cytokines were measured using high sensitivity multiplex bead-based assays.

RESULTS

We found overweight/obese MDD patients associated with higher plasma levels of tumor necrosis factor (TNF)-α, interleukin (IL)-8, and macrophage inflammatory protein (MIP)-1β and worse performance in speed of processing and working memory. The mediation analysis found higher levels of IL-8 (direct: β = -0.591 (95 % Confidence Interval (CI): -1.0 to -0.2), P = 0.002; indirect: β = 0.060 (95 % CI.: 0.0-0.2), P = 0.032) and TNF-α (direct: β = -0.589 (95 % CI.: -1.0 to -0.2), P = 0.002; indirect: β = 0.059 (95 % CI.: 0.1-0.2), P = 0.037) were associated with more deficits in speed of processing, and partially mediated the relationship between body mass index and speed of processing.

CONCLUSION

Our results suggest that elevated inflammation might be one biological mechanism underlying the link between higher body mass and deficits in processing speed in patients with MDD.

Neurocognitive deficits in depression: a systematic review of cognitive impairment in the acute and remitted state

Previous research suggests a broad range of deficits in major depressive disorder. Our goal was to update the current assumptions and investigate the extent of cognitive impairment in depression in the acute and remitted state. A systematic review of the existing literature between 2009 and 2019 assessing the risk of bias within the included studies was performed. Of the 42 articles reviewed, an unclear risk of bias was shown overall. The risk of bias mainly concerned the sample selection, inadequate remedial measures, as well as the lack of blinding the assessors. In the acute phase, we found strong support for impairment in processing speed, learning, and memory. Follow-up studies and direct comparisons revealed less pronounced deficits in remission, however, deficits were still present in attention, learning and memory, and working memory. A positive correlation between the number of episodes and cognitive deficits as well as depression severity and cognitive deficits was reported. The results also demonstrate a resemblance between the cognitive profiles in bipolar disorder and depression. Comparisons of depression with schizophrenia led to unclear results, at times suggesting an overlap in cognitive performance. The main findings support the global deficit hypothesis and align with results from prior meta-analyses and reviews. Recommendations for future research are also presented.

Neuroimaging Studies of Brain Structure in Older Adults with Bipolar Disorder: A Review

Bipolar disorder (BD) is a common mood disorder that can have severe consequences during later life, including suffering and impairment due to mood and cognitive symptoms, elevated risk for dementia and an especially high risk for suicide. Greater understanding of the brain circuitry differences involved in older adults with BD (OABD) in later life and their relationship to aging processes is required to improve outcomes of OABD. The current literature on gray and white matter findings, from high resolution structural and diffusion-weighted magnetic resonance imaging (MRI) studies, has shown that BD in younger age groups is associated with gray matter reductions within cortical and subcortical brain regions that subserve emotion processing and regulation, as well as reduced structural integrity of white matter tracts connecting these brain regions. While fewer neuroimaging studies have focused on OABD, it does appear that many of the structural brain differences found in younger samples are present in OABD. There is also initial suggestion that there are additional brain differences, for at least a subset of OABD, that may result from more pronounced gray and white matter declines with age that may contribute to adverse outcomes. Preclinical and clinical data supporting neuro-plastic and -protective effects of mood-stabilizing medications, suggest that treatments may reverse and/or prevent the progression of brain changes thereby reducing symptoms. Future neuroimaging research implementing longitudinal designs, and large-scale, multi-site initiatives with detailed clinical and treatment data, holds promise for reducing suffering, cognitive dysfunction and suicide in OABD.

Similarities and differences in working memory and neurometabolism of obsessive-compulsive disorder and major depressive disorder

BACKGROUND

Obsessive-compulsive disorder (OCD) and major depressive disorder (MDD) both showed cognitive impairment, and the altered neurometabolic may associate with cognitive impairment. However, there are limited comparative working memory (WM) and neuroimaging studies on these two disorders. Therefore, we investigated the characteristics of WM and neurometabolic changes in patients with OCD and MDD.

METHODS

A total of 64 unmedicated patients (32 OCD and 32 MDD), and 33 healthy controls (HC) were included to conduct WM assessment comprising Digit Span Test (DST), 2-back task and Stroop Color and Word Test (SCWT). Additionally, all subjects underwent protons magnetic resonance spectroscopy (¹H-MRS) to collect neurometabolic ratios of N-acetyl aspartate (NAA) and choline-containing compounds (Cho) to creatine (Cr) in the prefrontal cortex (PFC) and lentiform nucleus (LN). Finally, differential and correlation analysis were conducted to investigate their characteristics and relationships.

RESULTS

Compared with HC, both OCD and MDD patients exhibited a lower accuracy rate in the 2-back task, and only MDD patients performed worse in DST scores and longer reaction times in SCWT (all p < 0.05). Both OCD and MDD patients had lower NAA/Cr ratios in bilateral PFC (all p < 0.05). And the decreased NAA/Cr ratios in right PFC were positively correlated to DST scores in MDD group (r = 0.518, p = 0.003).

CONCLUSIONS

Both OCD and MDD showed WM impairment and neurometabolic alterations in PFC. Besides, MDD performed more severe and broader WM impairment compared to OCD. Moreover, the dysfunction of PFC may underlie the neural basis of WM impairment in MDD.

The prevalence and characteristics of MCCB cognitive impairment in unmedicated patients with bipolar II depression and major depressive disorder

BACKGROUND

Cognitive impairment has been acknowledged as a core clinical manifestation of bipolar disorder (BD) as well as major depressive disorder (MDD). Determining the prevalence and characteristics of cognitive impairment is important for clinical interventions. This study investigated the prevalence and characteristics of cognitive impairment based on the Measurement and Treatment Research to Improve Cognition Schizophrenia Consensus Cognitive Battery (MCCB) in both BD and MDD.

METHOD

One hundred and forty-nine BD II depression, 147 MDD, and 124 demographically matched healthy controls (HC) underwent MCCB cognitive assessment. The prevalence of MCCB cognitive impairment and group difference comparisons were performed. Additionally, association analysis was performed to investigate the relationship between cognitive performance and clinical variables.

RESULTS

Compared to the HC group, both BD II depression and MDD groups had a significantly reduced performance for all MCCB cognitive domains (all p < 0.05). The numerical scores for visual learning were lower in the BD II depression group compared to the MDD group. 32.89% of the BD II depression patients had clinically significant impairment (>1.5 SD below the normal mean) in two or more MCCB domains compared to 23.13% for MDD patients.

CONCLUSIONS

A high percent of patients in the BD II depression and MDD group exhibited MCCB cognitive impairments with clinical significance. Cognitive impairments were more common in BD II depression patients compared to MDD patients, particularly for visual learning. These findings suggest that clinicians should be aware of the severe cognitive impairment in mood disorders and establish effective cognitive screening and intervention strategies.

Neuropsychological aspects of bipolar disorder

Bipolar disorder (BD) is a chronic condition with serious consequences on the health and functionality of patients who suffer from it, with a high heritability and segregation, and aprevalence of between 1% and 2%. Neuropsychological deficits have been implicated as a very important issue related to BD prognosis, so a review was conducted of these deficits, the related factors and their functional consequences. It has been determined that the presence of neuropsychological deficits can vary in patients with BD according to their mood state, with a great influence of depressive symptoms on the cognitive variability of patients with respect to the general population and differences with respect to patients in the manic phase. In euthymic patients, the most affected cognitive domains are those of memory, attention, and executive function, associated with a more severe disease, sociodemographic vulnerability factors, and stable over time. A relationship has been found between poor cognitive performance, especially executive dysfunction, and objective functional deficit. Furthermore, cognitive differences have been outlined between BD and other serious mental illnesses that are described in this review.

Features of cognitive impairment and related risk factors in patients with major depressive disorder: A case-control study

BACKGROUND

Cognitive impairment (CI) is a common symptom contributing to functional loss in major depressive disorder (MDD). However, the features of CI and its related risk factors in young and middle-aged MDD patients remain unclear.

METHODS

In this case-control study, 18- to 55-year-old acute-onset MDD patients and healthy controls (HCs) were recruited from nine centers in China. MDD patients were diagnosed based on the DSM-IV, the Mini-International Neuropsychiatric Interview, and a 17-item Hamilton Rating Scale for Depression score ≥ 14. Cognitive function, including attention/vigilance, learning, memory, processing speed and executive function, was assessed with a neuropsychological battery and compared between MDD patients and HCs. MDD patients scoring 1.5 SDs below the mean HC score in at least 2 domains were defined as having CI. Logistic regression analysis was used to identify risk factors for CI in MDD patients.

RESULTS

Compared with HCs (n = 302), MDD patients (n = 631) showed significant impairment in all cognitive domains (P < 0.001); 168 MDD patients (26.6%) had CI. Male sex (OR: 1.712; 95% CI: 1.165-2.514; P < 0.01) was positively correlated with CI; age of first onset (OR: 0.974; 95% CI: 0.957-0.991; P < 0.05) and comorbid anxiety disorders (OR: 0.514; 95% CI: 0.332-0.797; P < 0.01) were negatively correlated with CI.

LIMITATIONS

Biomarkers and neuroimaging were not used to investigate the possible biological mechanism and neural basis of CI in MDD.

CONCLUSIONS

CI was prominent in adults with acute-onset MDD; male sex and younger age of first onset were independent risk factors, and comorbid anxiety disorders were a protective factor.

Thyroid hormones disturbances, cognitive deficits and abnormal dynamic functional connectivity variability of the amygdala in unmedicated bipolar disorder

OBJECTIVE

Accumulating evidence suggests that hypothalamus-pituitary-thyroid (HPT) axis dysfunction is relevant to the neuropsychological and pathophysiology functions of bipolar disorder (BD). However, no research has investigated the inter-relationships among thyroid hormones disturbance, neurocognitive deficits, and aberrant brain function (particularly in the amygdala) in patients with BD.

MATERIALS AND METHODS

Data of dynamic resting-state functional connectivity (rs-dFC) were gathered from 59 patients with unmedicated BD II during depressive episodes and 52 healthy controls (HCs). Four seeds were selected (the bilateral lateral amygdala and the bilateral medial amygdala). The sliding-window analysis was applied to investigate dynamic functional connectivity (dFC). Additionally, the serum thyroid hormone (free tri-iodothyronine (FT3), total tri-iodothyronine (TT3), free thyroxin (FT4), total thyroxin (TT4) and thyroid-stimulating hormone (TSH)) levels, and cognitive scores on the MATRICS Consensus Cognitive Battery (MCCB) in patients and HCs were detected.

RESULTS

The BD group exhibited increased dFC variability between the left medial amygdala and right medial prefrontal cortex (mPFC) when compared with the HC group. Additionally, the BD group showed lower FT3, TT3, and TSH level, higher FT4 level, and poorer cognitive score. Moreover, a significant negative correlation was observed between the dFC variability of the left medial amygdala-right mPFC and TSH level, or reasoning and problem solving of MCCB score in BD group. Multiple regression analysis showed that the TSH level × dFC variability of the medial amygdala-mPFC was an independent predictor for cognitive processing speed in BD group.

CONCLUSIONS

This study revealed patients with BD II depression had excessive variability in dFC between the medial amygdala and mPFC. Moreover, both HPT axis dysfunction and abnormal dFC of the amygdala-mPFC might be implicated in cognitive impairment in the early stages of BD.

Verbal learning, working memory, and attention/vigilance may be candidate phenotypes of bipolar II depression in Chinese Han nationality

OBJECTIVES

Bipolar II depression (BD-II) is a subtype of bipolar disorder with recurrent depressive, manic, and frequent depressive episodes as the main clinical manifestations. This study aimed to compare the cognitive function of patients with BD-II with those of healthy siblings and controls to explore the internal phenotype of BD-II in the field of cognitive function.

METHODS

66 BD-II patients, 58 healthy siblings, and 55 healthy controls were assessed with the Trail Making Test (TMT), Digit Symbol Coding Test (DSCT), Category Fluency, Hopkins Verbal Learning Test-Revised (HVLTR), Brief Visuospatial Memory Test-Revised (BVMT-R), Wechsler Memory Scale 3rd ed. Spatial Span Subtest (WMS-III SS), Neuropsychological Assessment Battery Mazes (NABM), Continuous Performance Test, and Identical Pairs (CPT-IP).

RESULTS

Patients with BD-II showed cognitive deficits in visual learning, reasoning and problem solving, verbal learning, attention/vigilance, working memory, and speed of processing. Healthy siblings showed cognitive deficits in reasoning and problem solving, verbal learning, attention/vigilance, working memory, and speed of processing. Substantial differences were observed among the three groups in reasoning and problem solving.

CONCLUSIONS

Verbal learning, working memory, and attention/vigilance may be potential endophenotypes that can be used to identify BD-II among Han Chinese in the early stage.

Transdiagnostic neurocognitive deficits in patients with type 2 diabetes mellitus, major depressive disorder, bipolar disorder, and schizophrenia: A 1-year follow-up study

BACKGROUND

Neurocognition impairments are critical factors in patients with major depressive disorder (MDD), bipolar disorder (BD), and schizophrenia (SZ), and also in those with somatic diseases such as type 2 diabetes mellitus (T2DM). Intriguingly, these severe mental illnesses are associated with an increased co-occurrence of diabetes (direct comorbidity). This study sought to investigate the neurocognition and social functioning across T2DM, MDD, BD, and SZ using a transdiagnostic and longitudinal approach.

METHODS

A total of 165 participants, including 30 with SZ, 42 with BD, 35 with MDD, 30 with T2DM, and 28 healthy controls (HC), were assessed twice at a 1-year interval using a comprehensive, integrated test battery on neuropsychological and social functioning.

RESULTS

Common neurocognitive impairments in somatic and psychiatric disorders were identified, including deficits in short-term memory and cognitive reserve (p < 0.01, η²p=0.08-0.31). Social functioning impairments were observed in almost all the disorders (p < 0.0001; η²p=0.29-0.49). Transdiagnostic deficits remained stable across the 1-year follow-up (p < 0.001; η²p=0.13-0.43) and could accurately differentiate individuals with somatic and psychiatric disorders (χ² = 48.0, p < 0.0001).

LIMITATIONS

The initial sample size was small, and high experimental mortality was observed after follow-up for one year.

CONCLUSIONS

This longitudinal study provides evidence of some possible overlap in neurocognition deficits across somatic and psychiatric diagnostic categories, such as T2DM, MDD, BD, and SZ, which have high comorbidity. This overlap may be a result of shared genetic and environmental etiological factors. The findings open promising avenues for research on transdiagnostic phenotypes of neurocognition in these disorders, in addition to their biological bases.

Low BDNF levels in serum are associated with cognitive impairments in medication-naïve patients with current depressive episode in BD II and MDD

OBJECTIVE

This study aimed to investigate the role of Brain-derived neurotrophic factor (BDNF) in clinical and cognitive outcomes in medication-naïve patients with Bipolar type II disorder (BD II) and Major depressive disorder (MDD).

METHODS

45 outpatients with BD II, 40 outpatients with MDD and 40 healthy controls (HCs) were recruited, and sociodemographic and clinical data were collected. Their BDNF serum levels were measured and analyzed with the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS).

RESULTS

BDNF levels were significantly lower in BD II patients than in MDD patients and HCs (p = 0.001). BD II and MDD patients had similar cognitive performance deficits shown on Attention (p = 0.001), Delayed memory (p = 0.001), and RBANS total score (p = 0.001). BDNF levels were positively associated with Visuospatial / constructional and Stroop color-word in BD II group, and with language in MDD group. The area under the curve (AUC) of the ROC analysis in BD II vs. MDD was 0.664, therefore, BDNF levels could not distinguish BD II from MDD.

CONCLUSION

Our study showed the decreased serum BDNF in MDD and BD II patients, suggesting BDNF may be involved in the pathophysiology of MDD and BD II. BDNF and cognitive deficits are both of low efficiency in distinguishing BD II from MDD. Decrease of BDNF may potentially indicate cognitive dysfunction in BD II and MDD patients with a current depressive episode.

Shared and distinct brain fMRI response during performance of working memory tasks in adult patients with schizophrenia and major depressive disorder

Working memory (WM) impairments are common features of psychiatric disorders. A systematic meta-analysis was performed to determine common and disorder-specific brain fMRI response during performance of WM tasks in patients with SZ and patients with MDD relative to healthy controls (HC). Thirty-four published fMRI studies of WM in patients with SZ and 18 published fMRI studies of WM in patients with MDD, including relevant HC, were included in the meta-analysis. In both SZ and MDD there was common stronger fMRI response in right medial prefrontal cortex (MPFC) and bilateral anterior cingulate cortex (ACC), which are part of the default mode network (DMN). The effects were of greater magnitude in SZ than MDD, especially in prefrontal-temporal-cingulate-striatal-cerebellar regions. In addition, a disorder-specific weaker fMRI response was observed in right middle frontal gyrus (MFG) in MDD, relative to HC. For both SZ and MDD a significant correlation was observed between the severity of clinical symptoms and lateralized fMRI response relative to HC. These findings indicate that there may be common and distinct anomalies in brain function underlying deficits in WM in SZ and MDD, which may serve as a potential functional neuroimaging-based diagnostic biomarker with value in supporting clinical diagnosis, measuring illness severity and assessing the efficacy of treatments for SZ and MDD at the brain level.

The Effects of Bilateral Theta-burst Stimulation on Executive Functions and Affective Symptoms in Major Depressive Disorder

Major depressive disorder (MDD) is characterized by severe affective as well as cognitive symptoms. Moreover, cognitive impairment in MDD can persist after the remission of affective symptoms. Theta-burst stimulation (TBS) is a promising tool to manage the affective symptoms of major depressive disorder (MDD); however, its cognition-enhancing effects are sparsely investigated. Here, we aimed to examine whether the administration of bilateral TBS has pro-cognitive effects in MDD. Ten daily sessions of neuronavigated active or sham TBS were delivered bilaterally over the dorsolateral prefrontal cortex to patients with MDD. The n-back task and the attention network task were administered to assess working memory and attention, respectively. Affective symptoms were measured using the 21-item Hamilton Depression Rating Scale. We observed moderate evidence that the depressive symptoms of patients receiving active TBS improved compared to participants in the sham stimulation. No effects of TBS on attention and working memory were detected, supported by a moderate-to-strong level of evidence. The effects of TBS on psychomotor processing speed should be further investigated. Bilateral TBS has a substantial antidepressive effect with no immediate adverse effects on executive functions.

Association of altered thyroid hormones and neurometabolism to cognitive dysfunction in unmedicated bipolar II depression

BACKGROUND

The underlying mechanism of cognitive impairment in bipolar II depression (BD II) remains unclear. Studies show disturbances of the hypothalamus-pituitary-thyroid (HPT) axis are suspected of correlating to brain neurometabolic alterations and cognitive deficits in psychiatric disorders. While, the nature of their inter-relationships in BD II depression remain enigmatic.

METHODS

106 patients with unmedicated BD II depression and 100 healthy controls underwent cognitive function assessment using Trail Making Test, Part-A (TMT-A), Digit Symbol Substitution Test (DSST), and Semantic Verbal Fluency testing (SVF). Of those, 69 patients and 53 healthy controls had serum thyroid hormone levels measured including free tri-iodothyronine (FT3), total tri-iodothyronine (TT3), free thyroxin (FT4), total thyroxin (TT4) and thyroid-stimulating hormone (TSH). Additionally, 79 of the patients and 76 of the healthy controls underwent proton magnetic resonance spectroscopy (H-MRS) to obtain ratios of N-acetyl aspartate to creatine (NAA/Cr) and choline-containing compounds to creatine (Cho/Cr) in the prefrontal cortex (PFC), anterior cingulate cortex (ACC) and thalamus. Finally, association and multiple regression analysis were conducted to investigate their inter-relationships.

RESULTS

Patients with BD II depression showed significantly lower DSST and verbal fluency scores and longer completion time of TMT-A than did healthy controls. The FT3, TT3, and TSH levels of the BD cohort significantly decreased, while their FT4 levels increased. We also found significantly lower NAA/Cr ratios in the PFC and higher NAA/Cr ratios in the left thalamus of patients with BD II depression than in healthy controls. Furthermore, association analysis showed that increased FT4 negatively correlated to DSST and SVF, while increased FT4 correlation significantly with increasing TSH and DSST. Multiple regression analyses revealed relationships between TSH and NAA in the left PFC and the left thalamus, while correlating to SVF testing within the BD II depression cohort.

CONCLUSIONS

Our results demonstrate coinciding thyroid hormone abnormalities, cognitive dysfunction, and neurometabolic alterations of the PFC-thalamic circuitry occur in an early course of BD II depression. Further understanding of the interaction between thyroid-stimulating hormone and NAA/Cr of PFC-thalamic circuitry may shed light on the etiology of associated cognitive impairment.

Neuropsychological Aspects of Bipolar Disorder

Bipolar disorder (BD) is a chronic condition with serious consequences on the health and functionality of patients who suffer from it, with a high heritability and segregation, and a prevalence of between 1% and 2%. Neuropsychological deficits have been implicated as a very important issue related to BD prognosis, so a review was conducted of these deficits, the related factors and their functional consequences. It has been determined that the presence of neuropsychological deficits can vary in patients with BD according to their mood state, with a great influence of depressive symptoms on the cognitive variability of patients with respect to the general population and differences with respect to patients in the manic phase. In euthymic patients, the most affected cognitive domains are those of memory, attention, and executive function, associated with a more severe disease, sociodemographic vulnerability factors, and stable over time. A relationship has been found between poor cognitive performance, especially executive dysfunction, and objective functional deficit. Furthermore, cognitive differences have been outlined between BD and other serious mental illnesses that are described in the review.

Altered Fractional Amplitude of Low-Frequency Fluctuation in Major Depressive Disorder and Bipolar Disorder

Background: Discriminating between major depressive disorder (MDD) and bipolar disorder (BD) remains challenging and cognitive deficits in MDD and BD are generally recognized. In this study, the fractional amplitude of low-frequency fluctuation (fALFF) approach was performed to explore neural activity and cognition in first-episode, drug-naïve BD and MDD patients, as well as the relationship between altered fALFF values and clinical or psychometric variables. Methods: A total of 21 BD patients, 25 MDD patients, and 41 healthy controls (HCs) completed clinical assessments and resting-state functional magnetic resonance imaging (rs-fMRI) scans in this study. The rs-fMRI data were analyzed by fALFF method and Pearson correlation analyses were performed between altered fALFF values and clinical variables or cognition. Support vector machine (SVM) was adopted to identify the three groups from each other with abnormal fALFF values in the brain regions obtained by group comparisons. Results: (1) The fALFF values were significantly different in the frontal lobe, temporal lobe, and left precuneus among three groups. In comparison to HCs, BD showed increased fALFF values in the right inferior temporal gyrus (ITG) and decreased fALFF values in the right middle temporal gyrus, while MDD showed decreased fALFF values in the right cerebellar lobule IV/V. In comparison to MDD, BD showed decreased fALFF values in bilateral posterior cingulate gyrus and the right cerebellar lobule VIII/IX. (2) In the BD group, a negative correlation was found between increased fALFF values in the right ITG and years of education, and a positive correlation was found between decreased fALFF values in the right cerebellar lobule VIII/IX and visuospatial abilities. (3) The fALFF values in the right cerebellar lobule VIII/IX may have the ability to discriminate BD patients from MDD patients, with sensitivity, specificity, and accuracy all over 0.70. Conclusions: Abnormal brain activities were observed in BD and MDD and were related with cognition in BD patients. The abnormality in the cerebellum can be potentially used to identify BD from MDD patients.

The characteristic of cognitive impairments in patients with bipolar II depression and its association with N-acetyl aspartate of the prefrontal white matter

Background

Cognitive deficit is acknowledged as a core feature of clinical manifestations of bipolar disorder (BD). However, the underlying mechanism of cognitive impairment in bipolar II depression has remained uncertain. We aim to determine the association of cognitive impairments with biochemical metabolism using proton magnetic resonance spectroscopy (¹H-MRS) and a battery of neuropsychological testing.

Methods

The current study was designed to assess four cognitive domains in a sample of 110 patients with bipolar II depression and 110 healthy controls, using a battery of 6 cognitive tests, including the Digit Symbol Substitution Test (DSST), Wisconsin Cart Sorting Test (WCST), Trail Making Test Part B (TMT-B), Digit Span Test (DST), TMT-part A (TMT-A) and Verbal Fluency Test (VFT). Metabolite levels were obtained in the following brain regions of interest: bilateral prefrontal white matter (PWM), bilateral anterior cingulate cortex (ACC), bilateral lenticular nucleus (LN), and bilateral thalamus. N-acetyl aspartate (NAA)/creatine (Cr) and choline-containing compounds (Cho)/Cr ratios are analyzed.

Results

Patients with bipolar II depression performed significantly worse on DSST (score), TMT (completion time), DSB (score), and VFT (valid word number) when compared with healthy controls. In the bilateral PWM, NAA/Cr ratios in the PWM were significantly reduced (bilaterally) than those in healthy controls. Correlation analysis was conducted with data from patients with bipolar II depression, we found that the NAA/Cr ratio of the left PWM was positively correlated with the score of DS and DSB, and the NAA/Cr ratio of the right PWM was negatively correlated with the completion time of TMT-B.

Conclusions

Our findings suggested that psychomotor speed, executive function, working memory, and verbal fluency are impaired in patients with BD II depression. Hypoactivity NAA/Cr in bilateral PWM may be associated with BD II depression's pathophysiology and results in cognitive dysfunction.

The effects of cognitive reserve and depressive symptoms on cognitive performance in major depression and bipolar disorder

BACKGROUND

Significant heterogeneity is observed in the cognitive profiles of bipolar disorder (BD) and major depression (MDD), characterized in part by differences in individual and clinical variables such as cognitive reserve (CR) and depression severity. However, no other study evaluated how this variables may interact regarding neurocognitive functioning. The aim of the present exploratory study was to evaluate the interaction between different depressive symptoms severity, CR and diagnosis with neurocognitive functioning.

METHOD

202 participants (MDD=91; BD=111) classified either as euthymic, with mild depression or moderate to severe depression, and low or high CR completed a neuropsychological evaluation of verbal fluency, working memory (WM), inhibitory control (IC), cognitive flexibility (CF) and attention (Att).

RESULTS

Neuroprotective effects of CR were observed in patients with BD within a major depressive episode in WM, IC, FC and Att. In MDD, CR acted as a neuroprotective factor during euthymia and moderate to severe depression in the same cognitive functions. CR and depression severity differentiated the cognitive profiles of individuals with BD and MDD.

LIMITATIONS

Some variables related to neurocognitive performance like medication use, number of mood episodes, illness duration or previous hospitalizations were not controlled.

CONCLUSION

CR may be protective against cognitive impairment in both BD and MDD, and these effects were observed in euthymia and during depressive episodes of varying severity. These findings highlight the importance of investigating such variables in the neuropsychological evaluation of mood disorders, which may help to understand the cognitive heterogeneity within these populations.

Inhibitory Repetitive Transcranial Magnetic Stimulation to Treat Psychomotor Slowing: A Transdiagnostic, Mechanism-Based Randomized Double-Blind Controlled Trial

Psychomotor slowing is frequently distressing patients with depression and schizophrenia. Increased neural activity within premotor cortices is linked to psychomotor slowing. This transdiagnostic study tested whether add-on inhibitory repetitive transcranial magnetic stimulation (rTMS) of the supplementary motor area (SMA) may alleviate psychomotor slowing. Forty-five patients with severe psychomotor slowing (26 psychosis, 19 major depression) were randomized in this transdiagnostic, double-blind, parallel-group, sham-controlled trial of 15 daily sessions of add-on rTMS over 3 weeks. Treatment arms included inhibitory 1 Hz stimulation of the SMA, facilitatory intermittent theta burst stimulation (iTBS) of the SMA, facilitatory 15 Hz stimulation of the left dorsolateral prefrontal cortex (DLPFC), and sham stimulation of the occipital cortex. The primary outcome was response (&gt;30% reduction from baseline) according to the Salpêtrière Retardation Rating Scale (SRRS). Secondary outcomes were course of SRRS and further symptom rating scales. Last-observation carried forward method was applied to all subjects with baseline data. Response rates differed between protocols: 82% with inhibitory 1 Hz rTMS of the SMA, 0% with facilitatory iTBS of the SMA, 30% with sham, and 33% with 15 Hz DLPFC rTMS (χ 2 = 16.6, P &lt; .001). Dropouts were similarly distributed across protocols. Response rates were similar in the completer analysis. This transdiagnostic trial of rTMS demonstrates that inhibitory SMA stimulation may ameliorate psychomotor slowing in severely ill patients. It further provides proof-of-concept that motor inhibition is linked to increased neural activity in the SMA because the inhibitory protocol performed best in reducing symptoms.

Trial registration: NCT03275766 (www.clinicaltrials.gov).

Combined Measures of Psychomotor and Cognitive Alterations as a Potential Hallmark for Bipolar Depression

OBJECTIVE

The current study aimed to examine whether specific features of psychomotor retardation (PMR) and cognitive functioning established different profiles in unipolar (UD) and bipolar depression (BD).

METHODS

Two groups of age-matched patients with UD (n=54) and BD (n=20) completed the Montgomery-Asberg Depression Rating Scale (MADRS/60), the Montreal Cognitive Assessment (MoCA/30), and the Salpêtrière Retardation Rating Scale (SRRS/60). We analyzed the group effect and then performed intra-group analyses.

RESULTS

The BD patients have higher SRRS score, and lower MoCA score than UD despite no difference on the level of depression between UD and BD. Our results show that PMR can be predicted by the level of depression in UD and by the cognitive alteration and onset of disease in BD.

CONCLUSION

PMR is a relevant marker of depression. Our results highlight the importance of concomitant evaluation of psychomotor and cognitive functions in the distinction of UD and BD symptoms.