Are major depression and bipolar disorder neuropsychologically distinct? A meta-analysis of comparative studies

Cognitive reserve and cognition in mood disorders: A systematic review and meta-analysis

Cognitive functioning heterogeneity is a well-recognized phenomenon in individuals diagnosed with mood disorders. Cognitive Reserve (CR) has been linked to multiple positive outcomes, including cognitive performance in these patients. This systematic review and meta-analysis aim to provide a comprehensive analysis of the relationship between CR and cognitive functioning in individuals with mood disorders, including bipolar disorder and depressive disorders. Following PRISMA guidelines, a systematic review and meta-analysis was conducted of original research exploring the relationship between CR and cognitive performance in adult individuals with mood disorders. The literature search was conducted on PubMed, Scopus, and Web of Science, from 2002 to September 2023, and the Newcastle-Ottawa Scale (NOS) was used to evaluate the quality of studies. Overall, 17 studies met the inclusion criteria for the systematic review and 11 for the meta-analysis. Both qualitative and quantitative findings suggested a positive relationship between CR measures and cognitive domains. CR emerges as a possible protective factor for cognitive functioning in adult individuals with mood disorders, potentially helping to mitigate the cognitive impairments associated with the disorder. These findings underscore the importance of the fact that promoting and enhancing CR could help in the cognitive prognosis of this population.

Cognition and gut microbiota in schizophrenia spectrum and mood disorders: A systematic review

FRILEUX, M., BOLTRI M. and al. Cognition and Gut microbiota in schizophrenia spectrum and mood disorders: a Systematic Review. NEUROSCI BIOBEHAV REV (1) 2024 Schizophrenia spectrum disorders and major mood disorders are associated with cognitive impairments. Recent studies suggest a link between gut microbiota composition and cognitive functioning. Here, we review the relationship between gut microbiota and cognition in these disorders. To do this, we conducted a systematic review, searching Cochrane Central Register of Controlled Trials, EBSCOhost, Embase, Pubmed, Scopus, and Web of Science. Studies were included if they investigated the relationship between gut microbiota composition and cognitive function through neuropsychological assessments in patients with bipolar, depressive, schizophrenia spectrum, and other psychotic disorders. Ten studies were identified. Findings underscore a link between gut dysbiosis and cognitive impairment. This relationship identified specific taxa (Haemophilus, Bacteroides, and Alistipes) as potential contributors to bolstered cognitive performance. Conversely, Candida albicans, Toxoplasma gondii, Streptococcus and Deinococcus were associated with diminished performance on cognitive assessments. Prebiotics and probiotics interventions were associated with cognitive enhancements, particularly executive functions. These results emphasize the role of gut microbiota in cognition, prompting further exploration of the underlying mechanisms paving the way toward precision psychiatry.

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 functioning in late life affective disorders: Comparing older adults with bipolar disorder, late life depression and healthy controls

INTRODUCTION

Both older age bipolar disorder (OABD) and late life depression (LLD) have been associated with cognitive dysfunction. It is unclear how cognitive functioning differs between these disorders and what the influence of current depressive symptoms is.

METHODS

We compared OABD (n = 148), LLD (n = 378) and healthy controls (HC) (n = 132) on cognitive functioning. Cognitive functioning was measured by an extensive neuropsychological assessment, and divided into four domains: episodic memory, processing speed, interference inhibition and working memory. Separate linear regression analyses were conducted with OABD as reference category, controlling for age, gender, level of education and severity of depressive symptoms.

RESULTS

Our findings show that OABD and LLD patients exhibit more cognitive dysfunction than HC, with OABD showing worst cognitive functioning on all cognitive domains, except for interference inhibition. These differences remained significant, even after controlling for the effect of depressive symptoms at the time of testing.

DISCUSSION

Our findings suggest that cognitive dysfunction in OABD is more severe in magnitude albeit in the same domains as in LLD. This difference cannot be fully explained by the severity of depressive symptoms. Future research should focus on other disease characteristics and how these characteristics are associated with the complex concept of cognitive functioning in both OABD and LLD.

Neurocognitive function of patients with melancholic and non-melancholic major depressive episodes: An exploratory study

OBJECTIVE

The aim of this exploratory study was to compare the neurocognitive performance of patients undergoing melancholic and non-melancholic major depressive episodes. Considering potential limitations of the Diagnostic and Statistical Manual of Mental Disorders (5th ed.) specifier, we employed an additional tool that has proven useful in identifying melancholia (the Sydney Melancholia Prototype Index).

METHODS

One hundred forty-one depressed inpatients were classified as melancholic or non-melancholic according to the Sydney Melancholia Prototype Index and the Diagnostic and Statistical Manual of Mental Disorders (5th ed.) criteria and compared on a neurocognitive battery selected to assess attention and processing speed, verbal memory, working memory and executive functions. Results were controlled for several potential confounders.

RESULTS

Patients diagnosed as melancholic by the two diagnostic systems displayed lower scores in executive measures, semantic verbal fluency and phonological verbal fluency. On attention and processing speed, patients with melancholia underperformed those with non-melancholic depression only when diagnosed by the Sydney Melancholia Prototype Index. After controlling for confounders, associations between melancholic status and executive dysfunction remained significant for the Sydney Melancholia Prototype Index but not for the Diagnostic and Statistical Manual of Mental Disorders (5th ed.) diagnosis.

CONCLUSION

In this study, melancholia diagnosed by the Sydney Melancholia Prototype Index (but not by the Diagnostic and Statistical Manual of Mental Disorders [5th ed.] criteria) was characterized by a greater compromise of tests assessing executive functions than non-melancholic depressions, even after controlling for depressive severity. These preliminary results might contribute to generating hypotheses about differences in the cognitive profile and pathophysiological substrate between melancholic and non-melancholic depressions. Likewise, the pattern of findings supports the hypothesis that the Diagnostic and Statistical Manual of Mental Disorders (5th ed.) melancholia specifier might identify more severe forms of depressive episodes rather than a qualitatively different subtype.

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.

Functional near-infrared spectroscopy during the verbal fluency task of English-Speaking adults with mood disorders: A preliminary study

Functional near-infrared spectroscopy (fNIRS) provides a direct and objective assessment of cerebral cortex function. It may be used to determine neurophysiological differences between psychiatric disorders with overlapping symptoms, such as major depressive disorder (MDD) and bipolar disorder (BD). Therefore, this preliminary study aimed to compare fNIRS signals during the verbal fluency task (VFT) of English-speaking healthy controls (HC), patients with MDD and patients with BD. Fifteen HCs, 15 patients with MDD and 15 patients with BD were recruited. Groups were matched for age, gender, ethnicity and education. Relative oxy-haemoglobin and deoxy-haemoglobin changes in the frontotemporal cortex was monitored with a 52-channel fNIRS system. Integral values of the frontal and temporal regions were derived as a measure cortical haemodynamic response magnitude. Both patient groups had lower frontal and temporal region integral values than HCs, and patients with MDD had lower frontal region integral value than patients with BD. Moreover, patients could be differentiated from HCs using the frontal and temporal integral values, and patient groups could be differentiated using the frontal region integral values. VFT performance, clinical history and symptom severity were not associated with integral values. These results suggest that prefrontal cortex haemodynamic dysfunction occurs in mood disorders, and it is more extensive in MDD than BD. The fNIRS-VFT paradigm may be a potential tool for differentiating MDD from BD in clinical settings, and these findings need to be verified in a larger sample of English-speaking patients with mood disorders.

Cognitive Profile and Relationship with Quality of Life and Psychosocial Functioning in Mood Disorders

BACKGROUND

Comparisons between healthy controls (HCs) and individuals with mood disorders have shown more cognitive dysfunction among the latter group, in particular in bipolar disorder (BD). This study aimed to characterize the pattern of cognitive function of BD and major depressive disorder (MDD) and compare them to HC using the (CogState Research Battery) CSRB™.

METHOD

Participants were tested, comprising the following domains: processing speed, attention, working memory, visual memory, executive functions, and verbal memory. Quality of life and functionality were also assessed. Multiple linear regression models were performed to examine the effect of demographic characteristics and functionality on cognitive outcomes separately for BD and MDD.

RESULTS

Ninety individuals participated in the study, of which 32 had BD, 30 had MDD, and 28 were HC. Differences were found between both BD and MDD and HC for the composite cognitive score, with significant differences between BD and HC (Diff = -5.5, 95% CI = [-9.5, -1.5], p = 0.005), and MDD and HC (Diff = -4.6, 95% CI = [-8.6, -0.5], p = 0.025). There were overall significant differences in five cognitive domains: processing speed (p = 0.001 and p = 0.004), attention (p = 0.002), working memory (p = 0.02), visual memory (p = 0.021), and verbal memory (p = 0.007). BD also presented worse performance than both MDD and HC, and MDD presented better performance than BD but worse than HC in quality of life and functionality. Multiple linear regression models were significative for education (p < 0.001) and age (p = 0.004) for BD and education (p < 0.001) for MDD.

CONCLUSION

In general, cognition is more affected in BD than MDD, which could be associated with functional and quality of life impairment.

Performance on the Wechsler Adult Intelligence Scale (WAIS) in Japanese patients with bipolar and major depressive disorders in euthymic and depressed states

AIM

This study aimed to examine the cognitive performance of patients with bipolar disorder (BD) stratified by illness phase compared to that of patients with major depressive disorder (MDD) and healthy controls.

METHODS

Participants were 139 patients with BD (55 euthymic and 84 depressed), 311 patients with MDD (88 euthymic and 223 depressed), and 386 healthy controls who underwent the Wechsler Adult Intelligence Scale-Revised or the Third Edition. They were non-elderly Japanese individuals with normal estimated premorbid intelligence quotient (IQ; >90), group-matched for age, sex, and premorbid IQ.

RESULTS

The depressed BD group showed significantly lower scores on verbal IQ, performance IQ, full-scale IQ, and three group indexes of perceptual organization, working memory, and processing speed when compared with healthy controls (all P < 0.001). All IQs and working memory index were also significantly lower than those of the depressed MDD group. The depressed MDD group scored significantly lower than controls in performance IQ (P < 0.001), full-scale IQ, and only in the index of processing speed (P < 0.001). The euthymic BD group scored significantly lower than controls in performance IQ (P = 0.004), whereas the euthymic MDD group scored significantly lower than controls only in processing speed (P = 0.030).

CONCLUSION

Patients with BD appear to have global and more intense cognitive impairments in depressed states compared with those with MDD whose impairments seem to be apparent only in processing speed in the Wechsler Adult Intelligence Scale. Attenuated impairments appear to exist in euthymic states of both patients.

Neurocognitive functioning in bipolar disorder: What we know and what we don’t

Introduction: This narrative review of systematic reviews and meta-analyses aims at compiling available evidence in various aspects of neurocognitive functioning in Bipolar Disorder (BD).

Methods: We conducted a MEDLINE literature search and identified 38 relevant systematic reviews and metaanalyses.

Results: Current evidence suggests that BD is associated with cognitive impairment across multiple domains and during all clinical states. However, there is a considerable cognitive heterogeneity within BD, which cannot be explained by clinical subtypes, and the pattern of neurocognitive impairment in BD overlaps with other psychiatric conditions such as major depression and schizophrenia. Residual depressive symptoms, poor clinical course and higher number of manic episodes may negatively impact cognitive performance, which is a major predictor of general functioning in BD. Evidence from available prospective studies does not support the notion of progressive cognitive decline in BD while some evidence exists to suggest patients may show some improvements in cognitive functioning following the first manic episode. Furthermore, a subset of patients may show premorbid cognitive abnormalities that could signal an early neurodevelopmental aetiology. Preliminary findings from small studies identify potential pro-cognitive effects of Cognitive Remediation, erythropoietin, intranasal insulin, lurasidone, mifepristone, repetitive Transcranial Magnetic Stimulation and transcranial Direct Current Stimulation in BD.

Discussion: Longitudinal studies in high-risk individuals can provide a better understanding of the development and progression of neurocognitive impairment in BD. Largescale randomised control trials are needed to compare the pro-cognitive efficacy of various pharmacological and non-pharmacological interventions in different cognitive subgroups of patients at different stages of BD.

Rumination in major depressive and bipolar disorder - a meta-analysis

BACKGROUND

rumination, defined as repetitive thoughts about emotionally relevant experiences, has been linked extensively with mood disorders, especially major depressive disorder (MDD).¹ However, there is a growing body of evidence suggesting the importance of rumination in bipolar disorder (BD)² as well.

METHODS

we searched for studies that investigated rumination in both BD and MDD in four databases. Our systematic search identified 12 studies with an overall sample size of 2071 clinical patients.

RESULTS

results demonstrated no significant difference in the ruminative tendencies of the two patient groups when all rumination measures were included. We tested for the effect of rumination subtype, BD subgroups, and the current mood state of BD and MDD patients. There were no significant differences in terms of depressive rumination, however, BD patients reported more rumination on positive affect. This difference remained significant when examining in BD-I³ and BD-II⁴ patient groups, with similar effect sizes.

LIMITATIONS

due to the lack of sufficient data in the literature, only a few self-report studies qualified to be included in our analysis. Thus additional moderating factors, such as the current mood state of the two patient groups could not be analyzed.

CONCLUSIONS

this review demonstrates that rumination is a significant process in both MDD and BD, highlighting the importance of interventions to reduce rumination in mood disorders. The two patient groups share several commonalities in terms of rumination, however, rumination subtype was found to be an important moderating variable underlining a difference in rumination on positive affect.

Duration of untreated illness and depression severity are associated with cognitive impairment in mood disorders

Introduction: In this study we estimated the rate and the trajectory of cognitive impairment in a naturalistic sample of outpatients with major depressive disorder (MDD) and bipolar disorder (BD) and its correlation with different variables.Materials and methods: An overall sample of 109 outpatients with MDD or BD was assessed for multiple clinical variables, including duration of untreated illness (DUI), and tested using the Montreal Cognitive Assessment (MoCA) during Major Depressive Episodes (MDE) and after remission. Correlations between MoCA scores and the clinical variables were then computed.Results: About 50% of patients with MDD and BD showed mild cognitive impairment during MDE. Improvement of cognitive function between depression and remission was significant, even though residual symptoms were observed especially in the most impaired patients. Of note, cognitive performance during depression was negatively associated with depression severity and DUI.Discussion: Present findings confirm available evidence about patterns of cognitive impairment in mood disorders, in terms of prevalence and persistence beyond remission in most severe cases. Moreover, a longer DUI was associated with worse cognitive performance during depression, and consequently with poorer outcome, underlining the importance of prompt treatment of these disorders also in light of a cognitive perspective.KeypointsAlthough distinct entities, unipolar and bipolar depression determine similar patterns of cognitive impairment in terms of severity and types of altered domains.Depression (but not anxiety) severity is associated with cognitive performance in depression.Prolonged duration of untreated illness is associated with more severe cognitive impairment during depression, particularly but not specifically in bipolar disorder.

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.

Distinctive Neuroanatomical Substrates for Depression in Bipolar Disorder versus Major Depressive Disorder

No neuroanatomical substrates for distinguishing between depression of bipolar disorder (dBD) and major depressive disorder (dMDD) are currently known. The aim of the current multicenter study was to identify neuroanatomical patterns distinct to depressed patients with the two disorders. Further analysis was conducted on an independent sample to enable generalization of results. We directly compared MR images of these subjects using voxel-based morphometry (VBM) and a support vector machine (SVM) algorithm using 1531 participants. The VBM analysis showed significantly reduced gray matter volumes in the bilateral dorsolateral prefrontal (DLPFC) and anterior cingulate cortices (ACC) in patients with dBD compared with those with dMDD. Patients with the two disorders shared small gray matter volumes for the right ACC and left inferior frontal gyrus when compared with healthy subjects. Voxel signals in these regions during SVM analysis contributed to an accurate classification of the two diagnoses. The VBM and SVM results in the second cohort also supported these results. The current findings provide new evidence that gray matter volumes in the DLPFC and ACC are core regions in displaying shared and distinct neuroanatomical substrates and can shed light on elucidation of neural mechanism for depression within the bipolar/major depressive disorder continuum.

Objective and biological markers in bipolar spectrum presentations

INTRODUCTION

Subthreshold presentations of bipolarity (BSPs) pose a diagnostic conundrum, in terms of whether they should be conceptualized and treated similarly as traditionally defined bipolar disorders (BD). While it has been argued that BSPs are on a pathophysiologic continuum with traditionally defined BDs, there has been limited examination of biological and objective markers in these presentations to validate this assertion. Areas covered: The authors review studies examining genetic, neurobiological, cognitive and peripheral markers in BSPs, encompassing clinical and non-clinical populations with subthreshold hypo/manic symptoms. Results are placed in the context of previously identified markers in traditionally defined BDs. Expert commentary: There have been few studies of objective and biological markers in subthreshold presentations of BD, and results are mixed. While abnormalities in brain structure/functioning, peripheral inflammatory, and cognitive markers have been reported, it is unclear whether these findings are specific to BD or indicative of broad affective pathology. However, some studies suggest that increased sensitivity to reward and positive stimuli are shared between subthreshold and traditionally defined BDs, and may represent a point of departure from unipolar major depression. Further examination of such markers may improve understanding of subthreshold bipolar presentations, and provide guidance in terms of therapeutic strategies.

Comparison of cognitive performance in bipolar disorder, major depressive disorder, unaffected first-degree relatives, and healthy controls

AIM

The extent and specifics regarding cognitive dysfunction in patients with bipolar disorder (BD) or major depressive disorder (MDD) and their unaffected first-degree relatives (FDR) have not been addressed in any single study. The present study compared the cognitive function of patients with BD or MDD, their FDR, and healthy control (HC) individuals.

METHODS

The study population comprised adults (aged 18-55 years) with BD, adults with MDD, FDR (children or siblings of patients with BD or MDD), and HC (n = 105, 109, 85, and 95, respectively). The Repeatable Battery for the Assessment of Neuropsychological Status was used to assess neurocognitive functions, with five domains and 12 tests. A Wechsler Adult Intelligence Scale brief form was applied to evaluate IQ. Status of mood was assessed using the Young Mania Rating Scale and the Hamilton Depression Scale.

RESULTS

The mixed model indicated significant variation among the four groups in cognitive function. Cognitive impairments, compared to HC, progressively greater from least to most were found in: FDR, MDD, and BD (F = 32.74, P < 0.001). Years of education correlated with cognitive performance (F = 17.04, P < 0.001), as did IQ (F = 240.63, P < 0.001). The total score for the Hamilton Rating Scale for Depression negatively correlated with cognitive function (F = 5.78, P = 0.017).

CONCLUSION

Among the study groups, patients with BD had the most severe deficits, followed by MDD patients and FDR. Cognitive deficits could not be associated with a specific psychiatric disorder, but differences in degree were noted.

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

BACKGROUND

Bipolar disorder (BD) II is more likely to be misdiagnosed as major depressive disorder (MDD) than other types of BD, leading to incorrect treatment and poor outcomes. Previous studies have shown inconsistent results regarding the differences in cognitive deficits between the two disorders. To eliminate the compounding effects of medication and aging, we sought to investigate changes in cognitive function in medication-naïve, non-late-life patients with BDII and MDD.

METHODS

Three subject groups were enrolled: 30 depressed BDII patients, 30 depressed MDD patients and 30 healthy controls. All subjects underwent a battery of cognitive tests to assess 8 cognitive domains. The cognitive domains were compared between the three subject groups. In BDII and MDD, the effect sizes were computed as evaluation parameters, weighing the degree of the cognitive deficits and the correlations between cognitive test deficits and clinical variables were also computed.

RESULTS

Compared with the controls, the BDII and MDD patients were characterized by similar deficits in psychomotor speed, working memory, visual memory, attention switching and verbal fluency. Moderate to severe deficits in the majority of cognitive tests were observed in the BDII and MDD patients. Furthermore, correlations between the modified Wisconsin Card Sorting Test total errors and age of onset in the BDII patients and between correct digit span responses (backward and total) and depressive severity were found in the MDD patients.

CONCLUSIONS

Our findings suggest that BDII and MDD patients may suffer from similar profiles of cognitive domain deficits that may not assist in distinguishing between the two disorders. In addition, cognitive deficits may be correlated with the age of onset and depressive severity in mood disorders.

'Cool' and 'Hot' executive functions in suicide attempters with major depressive disorder

RATIONALE

The World Health Organization reports that, by 2030, depression is expected to be the largest contributor to disease burden. Only small proportion of patients with major depressive disorder (MDD) achieves remission and the majority of them do not achieve long-term functional recovery. One of the neuropsychological domains that have been shown to be particularly impaired in depression, is that of executive function (EF).

OBJECTIVES

We examined whether the patients with MDD with and without suicide attempts had deteriorated 'cool' EF and 'hot' EF.

METHODS

The study population comprised 34 MDD attempters, 36 MDD non-attempters, and 55 healthy controls. We adopted the symmetry span task (SSPAN) to measure the updating and the affective shifting task (AST) to measure the inhibition and set-shifting in general and in response to emotional material. The Iowa gambling task (IGT) was used to examine the affective decision-making ability.

RESULTS

After controlling for PHQ-9, Anxiety (HADS), suicidal ideation, education year and gender, we reported that (1) the MDD non-attempters had worse updating than the healthy controls and the MDD attempters; (2) the MDD attempters had worse general inhibition (GI) than the healthy controls and the MDD non-attempters; (3) the MDD non-attempters had worse general set-shifting (GS) than the healthy controls and the MDD attempters; (4) there was no between-group difference in the 'hot' EFs; and (5) MDD attempters with longer durations (over 5 years) since last attempt had worse general inhibition.

CONCLUSIONS

The disrupted 'cool' EFs patients with MDD are consistent with previous review and meta-analytic studies. On the other hand, the two groups with MDD performed similarly to the healthy controls in the 'hot' EF.

Korsakoff Syndrome in Non-alcoholic Psychiatric Patients. Variable Cognitive Presentation and Impaired Frontotemporal Connectivity

Background: Non-alcoholic Wernicke's encephalopathy and Korsakoff syndrome are greatly underdiagnosed. There are very few reported cases of neuropsychologically documented non-alcoholic Korsakoff syndrome, and diffusion tensor imaging (DTI) data are scarce. Methods: We report clinical characteristics and neuropsychological as well as radiological findings from three psychiatric patients (one woman and two men) with a history of probable undiagnosed non-alcoholic Wernicke's encephalopathy and subsequent chronic memory problems. Results: All patients had abnormal neuropsychological test results, predominantly in memory. Thus, the neuropsychological findings were compatible with Korsakoff syndrome. However, the neuropsychological findings were not uniform. The impairment of delayed verbal memory of the first patient was evident only when the results of the memory tests were compared to her general cognitive level. In addition, the logical memory test and the verbal working memory test were abnormal, but the word list memory test was normal. The second patient had impaired attention and psychomotor speed in addition to impaired memory. In the third patient, the word list memory test was abnormal, but the logical memory test was normal. All patients had intrusions in the neuropsychological examination. Executive functions were preserved, except for planning and foresight, which were impaired in two patients. Conventional MRI examination was normal. DTI showed reduced fractional anisotropy values in the uncinate fasciculus in two patients, and in the corpus callosum and in the subgenual cingulum in one patient. Conclusions: Non-alcoholic Korsakoff syndrome can have diverse neuropsychological findings. This may partly explain its marked underdiagnosis. Therefore, a strong index of suspicion is needed. The presence of intrusions in the neuropsychological examination supports the diagnosis. Damage in frontotemporal white matter tracts, particularly in the uncinate fasciculus, may be a feature of non-alcoholic Korsakoff syndrome in psychiatric patients.

Cognitive impairment in schizophrenia and depression: A comparison of stability and course

Cognitive deficits are clinically relevant features in schizophrenia and depression, yet little comparative data on changes in both disorders is available. This study compares cognitive performance of inpatients with schizophrenia (N = 52) and unipolar major depression (N = 67) during psychiatric treatment, assessing performance twice: after admission to hospital (acute) and prior to discharge (postacute) on average seven weeks later. A group of healthy controls was tested at comparable intervals. Data was analyzed using a multivariate linear model. Patients with schizophrenia and depression showed significantly impaired performance compared to healthy controls. On follow-up both patient groups showed improved performance. Contrary to expectation, patients with schizophrenia showed greater improvement in verbal memory, visual memory, and psychomotor speed than depressive patients. Verbal fluency presented as a possible candidate to differentiate between both disorders. Similar profiles of generalized cognitive deficits were observed in both patient-groups on acute and postacute assessment, which might indicate trait-like deficits with persistent functional implications in both disorders. Findings do not support assumptions of greater cognitive impairment in schizophrenia compared to depression. A distinction of the disorders on the grounds of cognitive functioning seems to be less specific than presumed.

Decreased functional connectivity and disrupted neural network in the prefrontal cortex of affective disorders: A resting-state fNIRS study

BACKGROUND

Affective disorders (AD) have been conceptualized as neural network-level diseases. In this study, we utilized functional near infrared spectroscopy (fNIRS) to investigate the spontaneous hemodynamic activities in the prefrontal cortex (PFC) of the AD patients with or without medications.

METHODS

42 optical channels were applied to cover the superior frontal gyrus (SFG), middle frontal gyrus (MFG), and inferior frontal gyrus (IFG), which constitute one of the most important affective networks of the brain. We performed resting-state measurements on 28 patients who were diagnosed as having AD and 30 healthy controls (HC). Raw fNIRS data were preprocessed with independent component analysis (ICA) and a band-pass filter to remove artifacts and physiological noise.

RESULTS

By systematically analyzing the intra-regional, intrahemispheric, and interhemispheric connectivities based on the spontaneous oscillations of Δ[HbO], our results indicated that patients with AD exhibited significantly reduced intra-regional and symmetrically interhemispheric connectivities in the PFC when compared to HC. More specifically, relative to HC, AD patients showed significantly lower locally functional connectivity in the right IFG, and poor long-distance connectivity between bilateral IFG. In addition, AD patients without medication presented more disrupted cortical organizations in the PFC, and the severity of self-reported symptoms of depression was negatively correlated with the strength of intra-regional and symmetrically interhemispheric connectivity in the PFC.

LIMITATIONS

Regarding the measuring technique, fNIRS has restricted measurement depth and spatial resolution. During the study, the subgroups of AD, such as major depressive disorder, bipolar, comorbidity, or non-comorbidity, dosage of psychotropic drugs, as well as different types of pharmacological responses were not distinguished and systematically compared. Furthermore, due to the limitation of the research design, it was still not very clear how pharmacological treatment affected the resting state cortical organization of the prefrontal lobe, and the degree of the effect in patients with AD.

CONCLUSION

These results strongly supported that RSFC measured by fNIRS could be a useful and powerful way of delineating the neuropathology of AD.