Enduring cognitive dysfunction in unipolar major depression: a test-retest study using the Stroop paradigm

Change in Cognitive Function over the Course of Major Depressive Disorder: A Systematic Review and Meta-analysis

Major depressive disorder (MDD) is associated with significant cognitive deficits during the acute and remitted stages. The aim of this systematic review and meta-analysis was to examine the course of cognitive function whilst considering demographic, treatment, or clinical features of MDD that could moderate the extent of cognitive change. Databases were searched to identify studies that reported on cognitive function in MDD with a ≥12-week test-retest interval. Relevant studies were pooled using random effects modelling to generate an inverse-variance, weighted, mean effect size estimate (Hedges' g) of cognitive change for each cognitive variable and for an overall composite cognitive domain. Of 6898 records, 99 eligible studies were identified from which 69 were meta-analysed, consisting of 4639 MDD patients (agemean = 40.25 years, female% = 64.62%) across 44 cognitive variables. In over 95% of cognitive variables, improvements were either of non-significant, negligible, or of a small magnitude, and when compared to matched healthy controls, the possibility of practice effects could not be precluded. Depressive symptom improvement and the number of previous depressive episodes moderated the extent of cognitive change, demonstrating state- and scar-like features for one-quarter of the cognitive domains. Further longitudinal studies are required to elucidate the MDD cognitive trajectory from initial onset. Findings nonetheless suggest that following pharmacological and non-pharmacological treatment, cognitive change in MDD is typically small, but the capacity for change may be less with episode recurrence. Targeting cognition early in the course of illness may facilitate better prognosis and support a more complete functional recovery.

Longitudinal changes in attention bias to infant crying in primiparous mothers

Introduction

Infant stimuli attract caregiver attention and motivate parenting behavior. Studies have confirmed the existence of attentional bias toward infant face stimuli; however, relatively little is known about whether attentional bias exists for infant cry stimuli, which are as important as faces in child-rearing situations. Furthermore, scarce longitudinal evidence exists on how attentional bias toward infant crying changes through the postpartum period.

Methods

In the present study, we conducted an experiment to assess bias toward infant crying at two postpartum time points: at Time 1 (Mean = 75.24 days), 45 first-time mothers participated and at Time 2 (Mean = 274.33 days), 30 mothers participated. At both time points, the mothers participated in a Stroop task with infant crying and white noise as the stimuli. They were instructed to answer the color out loud as quickly and accurately as possible, while ignoring the sound. Four types of audio stimuli were used in this task (the cry of the mother's own infant, the cry of an unfamiliar infant, white noise matched to the cry of the mother's own infant, and white noise matched to the cry of an unfamiliar infant), one of which was presented randomly before each trial. Response time and the correct response rate for each condition were the dependent variables.

Results

For response time, the main effect of familiarity was significant, with longer response times when the participant's infant's cry was presented. In addition, response times were lower at Time 2 than at Time 1 in some conditions in which crying was presented.

Discussion

The results suggest that mothers may be less disturbed by infant crying as they gain more experience. Elucidating the characteristics of postpartum mothers' changes in cognitive performance related to infants' cries would be useful in fundamental and applied research to understand the process of parents' adaptation to parenting.

Dysregulation of adult hippocampal neuroplasticity in major depression: pathogenesis and therapeutic implications

Major depressive disorder (MDD) was previously hypothesized to be a disease of monoamine deficiency in which low levels of monoamines in the synaptic cleft were believed to underlie depressive symptoms. More recently, however, there has been a paradigm shift toward a neuroplasticity hypothesis of depression in which downstream effects of antidepressants, such as increased neurogenesis, contribute to improvements in cognition and mood. This review takes a top-down approach to assess how changes in behavior and hippocampal-dependent circuits may be attributed to abnormalities at the molecular, structural, and synaptic level. We conclude with a discussion of how antidepressant treatments share a common effect in modulating neuroplasticity and consider outstanding questions and future perspectives.

Cognitive Impairment and Neurocognitive Profiles in Major Depression-A Clinical Perspective

Increasingly, studies have investigated cognitive functioning from the perspective of acute state- to remitted phases of Major Depressive Disorder (MDD). Some cognitive deficits observed in the symptomatic phase persist in remission as traits or scars. The etiological origin and clinical consequences of the neurocognitive profiles reported in the literature are still unclear and may vary across populations. Deficits are suspected to influence the association between MDD and neurodegenerative disorders and could thus be of particular clinical consequence. The aim of this review is to describe the clinical neuropsychological profile in MDD and how it is related to research during the past decade on cognitive deficits in MDD from a state, trait, and scar perspective. This review, with a clinical perspective, investigates research from the past decade regarding cognitive functioning in MDD in a long-term perspective. We focus on the clinical manifestation of deficits, and the potential neurodegenerative consequences of the neurocognitive profile in MDD. Searches in Medline, PsycINFO and Embase were conducted targeting articles published between 2010 and 2020. Examination of the evidence for long-lasting neurocognitive deficits in major depression within the cognitive domains of Memory, Executive Functions, Attention, and Processing Speed was conducted and was interpreted in the context of the State, Scar and Trait hypotheses. Defining the neurocognitive profiles in MDD will have consequences for personalized evaluation and treatment of residual cognitive symptoms, and etiological understanding of mood disorders, and treatments could potentially reduce or delay the development of neurodegenerative disorders.

Depression and executive functioning bidirectionally impair one another across 9 years: Evidence from within-person latent change and cross-lagged models

BACKGROUND

Scar and vulnerability models assert that increased psychopathology may predict subsequent executive functioning (EF) deficits (and vice versa) over protracted timescales, yet most prior work on this topic has been cross-sectional. Thus, we tested the within- and between-person relations between EF, depression, and anxiety.

METHODS

Older adult participants (n = 856) were assessed across four waves, approximately 2 years apart. Performance-based EF and caregiver-rated symptom measures were administered. Bivariate latent change score and random-intercept cross-lagged panel models were conducted.

RESULTS

Within persons, random-intercept cross-lagged panel models revealed that prior greater depression forecasted lower subsequent EF, and vice versa (d = -0.292 vs. -0.292). Bivariate dual latent change score models showed that within-person rise in depression predicted EF decreases, and vice versa (d = -0.245 vs. -0.245). No within-person, cross-lagged, EF-anxiety relations emerged. Further, significant negative between-person EF-symptom relations were observed (d = -0.264 to -0.395).

CONCLUSION

Prospective, within-person findings offer some evidence for developmental scar and vulnerability models.

A Systematic Review of Executive Function and Information Processing Speed in Major Depression Disorder

Background: Major depression is a psychiatric disorder characterized neuropsychologically by poor performance in tasks of memory, attention, processing speed, and executive function. The aim of this systematic review was to examine the evidence regarding the neuropsychological profile of people with major depression and to determine which of two explanatory models—the processing speed hypothesis or the cognitive effort hypothesis—has most empirical support. Methods: We searched three relevant databases and reviewed the reference lists of the articles retrieved. The results obtained with the Trail Making Test and the Stroop Color-Word Test were reviewed for 37 studies published between 1993 and 2020. Results: The empirical evidence supports both hypotheses: cognitive effort and processing speed, suggesting that depression is not only characterized by psychomotor slowing but also involves a specific deficit in executive function. Discussion: We discuss potentially relevant variables that should be considered in future research in order to improve knowledge about the neurocognitive profile of depression. The main limitation of this study derives from the considerable heterogeneity of participants with MD, which makes it difficult to compare and integrate the data.

A Longitudinal 5-Year Follow-Up Study of Cognitive Function After First Episode Major Depressive Disorder: Exploring State, Scar and Trait Effects

Major depression (MDD) is associated with cognitive deficits in processing speed and executive function (EF) following first episode (FE). It is unclear whether deficits are state or trait related. Studies following FE MDD over longer periods are lacking, making it uncertain how cognition and symptoms develop after the initial episode. The present study assessed cognitive function and symptoms 5 years following FE MDD. In addition, the study explored relationships between MDD symptoms, rumination, and cognitive deficits with regards to the trait, state, and scar perspective. Twenty-three participants with previous FE MDD, and 20 matched control participants were compared on Delis-Kaplan Executive Function System measures of processing speed and EF, in a 5-year longitudinal follow-up study. Correlations between current symptoms- and history of MDD, rumination, cognition were investigated. Findings indicated that cognitive deficits persisted with no clear signs of exacerbation after initial episode. Inhibition appeared independent of current and previous symptoms of depression. Processing speed was related to depressive- symptoms and rumination. In conclusion, results indicated persisting, stable deficits in both EFs and processing speed. Findings further suggest that depressive symptoms could be related to deficits in processing speed, indicating state effects. There was limited support for worsening of cognition after initial episode. Some aspects of EF like Inhibition could show persistent deficits independent of depressive symptoms indicating trait effects.

Patient Perspective of Cognitive Symptoms in Major Depressive Disorder: Retrospective Database and Prospective Survey Analyses

Background

Major depressive disorder (MDD) is a common and burdensome condition. The clinical understanding of MDD is shaped by current research, which lacks insight into the patient perspective.

Objective

This two-part study aimed to generate data from PatientsLikeMe, an online patient network, on the perception of cognitive symptoms and their prioritization in MDD.

Methods

A retrospective data analysis (study 1) was used to analyze data from the PatientsLikeMe community with self-reported MDD. Information on patient demographics, comorbidities, self-rated severity of MDD, treatment effectiveness, and specific symptoms of MDD was analyzed. A prospective electronic survey (study 2) was emailed to longstanding and recently active members of the PatientsLikeMe MDD community. Study 1 analysis informed the objectives of the study 2 survey, which were to determine symptom perception and prioritization, cognitive symptoms of MDD, residual symptoms, and medication effectiveness.

Results

In study 1 (N=17,166), cognitive symptoms were frequently reported, including “severe” difficulty in concentrating (28%). Difficulty in concentrating was reported even among patients with no/mild depression (80%) and those who considered their treatment successful (17%). In study 2 (N=2525), 23% (118/508) of patients cited cognitive symptoms as a treatment priority. Cognitive symptoms correlated with depression severity, including difficulty in making decisions, concentrating, and thinking clearly (r_s=0.32, 0.36, and 0.34, respectively). Cognitive symptoms interfered with meaningful relationships and daily life tasks and had a profound impact on patients’ ability to work and recover from depression.

Conclusions

Patients acknowledge that cognitive dysfunction in MDD limits their ability to recover fully and return to a normal level of social and occupational functioning. Further clinical understanding and characterization of MDD for symptom prioritization and relapse risk due to residual cognitive impairment are required to help patients return to normal cognitive function and aid their overall recovery.

Early improvement of executive test performance during antidepressant treatment predicts treatment outcome in patients with Major Depressive Disorder

Executive dysfunctions frequently occur in patients with Major Depressive Disorder and have been shown to improve during effective antidepressant treatment. However, the time course of improvement and its relationship to treatment outcome is unknown. The aim of the study was to assess the test performance and clinical outcome by repetitive assessments of executive test procedures during antidepressant treatment. Executive test performance was assessed in 209 –patients with Major Depressive Disorder (mean age 39.3 ± 11.4 years) and 84 healthy controls five times in biweekly intervals from baseline to week 8. Patients were treated by a defined treatment algorithm within the early medication change study (EMC trial; ClinicalTrials.gov NCT00974155), controls did not receive any intervention. Cognitive domains were processing speed, cognitive flexibility, phonemic and semantic verbal fluency. Intelligence was assessed at baseline. Depression severity was tested once a week by the Hamilton Depression Rating Scale (HAMD₁₇). 130 patients (62%) showed executive dysfunctions in at least one of four tests at baseline. Linear mixed regression models revealed that the course of depression severity was associated to the course of cognitive flexibility (p = 0.004) and semantic verbal fluency (p = 0.020). Cognitive flexibility and semantic verbal fluency may be candidates easily to apply for therapy response prediction in clinical routine, which should be tested in further prospective studies.

Trial registration: ClinicalTrials.gov NCT00974155

EudraCT: 2008-008280-96

White matter correlates of impaired attention control in major depressive disorder and healthy volunteers

BACKGROUND

Major depressive disorder (MDD) is associated with impaired attention control and alterations in frontal-subcortical connectivity. We hypothesized that attention control as assessed by Stroop task interference depends on white matter integrity in fronto-cingulate regions and assessed this relationship using diffusion tensor imaging (DTI) in MDD and healthy volunteers (HV).

METHODS

DTI images and Stroop task were acquired in 29 unmedicated MDD patients and 16 HVs, aged 18-65 years. The relationship between Stroop interference and fractional anisotropy (FA) was examined using region-of-interest (ROI) and tract-based spatial statistics (TBSS) analyses.

RESULTS

ROI analysis revealed that Stroop interference correlated positively with FA in left caudal anterior cingulate cortex (cACC) in HVs (r = 0.62, p = 0.01), but not in MDD (r = -0.05, p= 0.79) even after controlling for depression severity. The left cACC was among 4 ROIs in fronto-cingulate network where FA was lower in MDD relative to HVs (F_(1,41) = 8.87, p = 0.005). Additionally, TBSS showed the same group interaction of differences and correlations, although only at a statistical trend level.

LIMITATIONS

The modest sample size limits the generalizability of the findings.

CONCLUSIONS

Structural connectivity of white matter network of cACC correlated with magnitude of Stroop interference in HVs, but not MDD. The cACC-frontal network, sub-serving attention control, may be disrupted in MDD. Less cognitive control may include enhanced effects of salience in HVs, or less effective response inhibition in MDD. Further studies of salience and inhibition components of executive function may better elucidate the relationship between brain white matter changes and executive dysfunction in MDD.

Clinical, Functional, and Biological Correlates of Cognitive Dimensions in Major Depressive Disorder - Rationale, Design, and Characteristics of the Cognitive Function and Mood Study (CoFaM-Study)

Cross-sectional and longitudinal studies exploring clinical, functional, and biological correlates of major depressive disorder are frequent. In this type of research, depression is most commonly defined as a categorical diagnosis based on studies using diagnostic instruments. Given the phenotypic and biological heterogeneity of depression, we chose to focus the phenotypic assessments on three cognitive dimensions of depression including (a) cognitive performance, (b) emotion processing, and (c) social cognitive functioning. Hence, the overall aim of the study is to investigate the long-term clinical course of these cognitive dimensions in depression and its functional (psychosocial) correlates. We also aim to identify biological "genomic" correlates of these three cognitive dimensions of depression. To address the above overall aim, we created the Cognition and Mood Study (CoFaMS) with the key objective to investigate the clinical, functional, and biological correlates of cognitive dimensions of depression by employing a prospective study design and including a healthy control group. The study commenced in April 2015, including patients with a primary diagnosis of a major depressive episode of major depressive disorder or bipolar disorder according to DSM-IV-TR criteria. The assessments cover the three cognitive dimensions of depression (cognitive performance, emotion processing, and social cognition), cognitive function screening instrument, plus functional scales to assess general, work place, and psychosocial function, depression symptom scales, and clinical course of illness. Blood is collected for comprehensive genomic discovery analyses of biological correlates of cognitive dimensions of depression. The CoFaM-Study represents an innovative approach focusing on cognitive dimensions of depression and its functional and biological "genomic" correlates. The CoFaMS team welcomes collaborations with both national and international researchers.

Cognitive remission: a novel objective for the treatment of major depression?

BACKGROUND

Cognitive dysfunction in major depressive disorder (MDD) encompasses several domains, including but not limited to executive function, verbal memory, and attention. Furthermore, cognitive dysfunction is a frequent residual manifestation in depression and may persist during the remitted phase. Cognitive deficits may also impede functional recovery, including workforce performance, in patients with MDD. The overarching aims of this opinion article are to critically evaluate the effects of available antidepressants as well as novel therapeutic targets on neurocognitive dysfunction in MDD.

DISCUSSION

Conventional antidepressant drugs mitigate cognitive dysfunction in some people with MDD. However, a significant proportion of MDD patients continue to experience significant cognitive impairment. Two multicenter randomized controlled trials (RCTs) reported that vortioxetine, a multimodal antidepressant, has significant precognitive effects in MDD unrelated to mood improvement. Lisdexamfetamine dimesylate was shown to alleviate executive dysfunction in an RCT of adults after full or partial remission of MDD. Preliminary evidence also indicates that erythropoietin may alleviate cognitive dysfunction in MDD. Several other novel agents may be repurposed as cognitive enhancers for MDD treatment, including minocycline, insulin, antidiabetic agents, angiotensin-converting enzyme inhibitors, S-adenosyl methionine, acetyl-L-carnitine, alpha lipoic acid, omega-3 fatty acids, melatonin, modafinil, galantamine, scopolamine, N-acetylcysteine, curcumin, statins, and coenzyme Q10. The management of cognitive dysfunction remains an unmet need in the treatment of MDD. However, it is hoped that the development of novel therapeutic targets will contribute to 'cognitive remission', which may aid functional recovery in MDD.

Impaired Maturation of Cognitive Control in Adolescents Who Develop Major Depressive Disorder

This study examined whether development of two forms of cognitive control (proactive and reactive) between early and midadolescence was associated with the onset of major depressive disorder (MDD) during the same period and if it prospectively predicted MDD onset between mid- and late adolescence. Adolescents (N = 165) completed 3 waves of assessments, at 12 (T1), 16 (T2), and 18 (T3) years of age. Diagnostic interviews were conducted at each time point to identify three groups of adolescents: "early MDD," those who developed MDD between early (T1) and mid- (T2) adolescence (n = 23); "late MDD," those who developed MDD between mid- (T2) and late (T3) adolescence (n = 20); and "controls," those who did not develop MDD (n = 122). A modified Stroop task was completed at T1 and T2 to examine development of proactive and reactive cognitive control. Adolescents with early MDD exhibited significant declines in reactive control, as well as a trend level decline for proactive control, during this period compared to controls. No significant differences in reactive or proactive control were identified in adolescents with late MDD compared to controls, but they did exhibit significant improvements in proactive control compared to those with early MDD. These findings suggest that normative maturation of reactive, and possibly proactive, cognitive control abilities are impaired in adolescents who develop MDD between early and midadolescence. This has implications for understanding the mechanisms underlying certain forms of behavioral dysregulation that are commonly seen in MDD.

Major depressive disorder: mechanism-based prescribing for personalized medicine

Individual patients with depression present with unique symptom clusters - before, during, and even after treatment. The prevalence of persistent, unresolved symptoms and their contribution to patient functioning and disease progression emphasize the importance of finding the right treatment choice at the onset and the utility of switching medications based on suboptimal responses. Our primary goal as clinicians is to improve patient function and quality of life. In fact, feelings of well-being and the return to premorbid levels of functioning are frequently rated by patients as being more important than symptom relief. However, functional improvements often lag behind resolution of mood, attributed in large part to persistent and functionally impairing symptoms - namely, fatigue, sleep/wake disturbance, and cognitive dysfunction. Thus, patient outcomes can be optimized by deconstructing each patient's depressive profile to its component symptoms and specifically targeting those domains that differentially limit patient function. This article will provide an evidence-based framework within which clinicians may tailor pharmacotherapy to patient symptomatology for improved treatment outcomes.

Abnormal activation of the occipital lobes during emotion picture processing in major depressive disorder patients

A large number of studies have demonstrated that depression patients have cognitive dysfunction. With recently developed brain functional imaging, studies have focused on changes in brain function to investigate cognitive changes. However, there is still controversy regarding abnormalities in brain functions or correlation between cognitive impairment and brain function changes. Thus, it is important to design an emotion-related task for research into brain function changes. We selected positive, neutral, and negative pictures from the International Affective Picture System. Patients with major depressive disorder were asked to judge emotion pictures. In addition, functional MRI was performed to synchronously record behavior data and imaging data. Results showed that the total correct rate for recognizing pictures was lower in patients compared with normal controls. Moreover, the consistency for recognizing pictures for depressed patients was worse than normal controls, and they frequently recognized positive pictures as negative pictures. The consistency for recognizing pictures was negatively correlated with the Hamilton Depression Rating Scale. Functional MRI suggested that the activation of some areas in the frontal lobe, temporal lobe, parietal lobe, limbic lobe, and cerebellum was enhanced, but that the activation of some areas in the frontal lobe, parietal lobe and occipital lobe was weakened while the patients were watching positive and neutral pictures compared with normal controls. The activation of some areas in the frontal lobe, temporal lobe, parietal lobe, and limbic lobe was enhanced, but the activation of some areas in the occipital lobe were weakened while the patients were watching the negative pictures compared with normal controls. These findings indicate that patients with major depressive disorder have negative cognitive disorder and extensive brain dysfunction. Thus, reduced activation of the occipital lobe may be an initiating factor for cognitive disorder in depressed patients.

Agomelatine: mechanism of action and pharmacological profile in relation to antidepressant properties

Agomelatine behaves both as a potent agonist at melatonin MT1 and MT2 receptors and as a neutral antagonist at 5-HT2C receptors. Accumulating evidence in a broad range of experimental procedures supports the notion that the psychotropic effects of agomelatine are due to the synergy between its melatonergic and 5-hydroxytryptaminergic effects. The recent demonstration of the existence of heteromeric complexes of MT1 and MT2 with 5-HT2C receptors at the cellular level may explain how these two properties of agomelatine translate into a synergistic action that, for example, leads to increases in hippocampal proliferation, maturation and survival through modulation of multiple cellular pathways (increase in trophic factors, synaptic remodelling, glutamate signalling) and key targets (early genes, kinases). The present review focuses on the pharmacological properties of this novel antidepressant. Its mechanism of action, strikingly different from that of conventional classes of antidepressants, opens perspectives towards a better understanding of the physiopathological bases underlying depression.

Cognitive function in first episode major depressive disorder: poor inhibition and semantic fluency performance

INTRODUCTION

Executive Functions (EF) has been documented to be impaired in patients with recurrent Major Depressive Disorder (MDD) in several studies. Longitudinal studies have suggested that these impairments may be a result of several episodes of depression or they may represent stable traits in this patient group. However, few studies have addressed these issues and investigated cognitive functioning with a particular focus on EF in patients who experience MDD for the first time.

METHODS

In the present study, the executive functions of inhibition, verbal fluency, mental flexibility, and planning and problem solving were investigated in a group of patients diagnosed with first episode MDD. Thirty patients and 30 control subjects were included in the study.

RESULTS

The patient group performed significantly more poorly in the cognitive functions of inhibition and semantic fluency. In addition, the patient group showed a reduced speed of mental processing on some of the measures. However, the results showed that reduced processing speed alone could not account for the poor performance in inhibition and semantic fluency. There were no differences between the two groups in the other measures of EF, indicating that functioning of mental flexibility, phonemic fluency, planning, and problem solving was intact in the patient group.

CONCLUSIONS

The results show that impaired inhibition and semantic fluency are present early in the course of MDD. The present findings indicate that poor inhibition and performance in semantic fluency may represent stable traits in MDD, independent of symptom severity and the number of depressive episodes.

A follow-up study of first episode major depressive disorder. Impairment in inhibition and semantic fluency-potential predictors for relapse?

The present study investigated the Executive Functions (EF) of inhibition, mental flexibility and phonemic and semantic fluency in a 1-year follow-up assessment of patients diagnosed with first episode Major Depressive Disorder (MDD). In the acute phase, the patient group performed significantly poorer compared to the control group (CG) in inhibition and semantic fluency. The present study pursued these findings from the acute phase to see if the impairment seen in inhibition and semantic fluency in the acute phase normalized or persisted in the follow-up assessment. In addition, the present study investigated the association between poor inhibition and semantic fluency performance and the experience of relapse during the 1-year period. Twenty eight patients and 28 individually matched control subjects were included. EF was reassessed using three tests from the Delis Kaplan Executive Function System (D-KEFS).

RESULTS

There was a significant decrease in depression severity score from the acute phase, showing that most of the patients were in remission in the follow-up assessment. RESULTS showed a sustained impairment in inhibition and semantic fluency in the patient group. However, the performance in inhibition was more severe when an additional requirement of mental flexibility was included. There were no group differences in the other EF functions measured. Further, patients with a relapse in the course of 1 year performed significantly poorer in inhibition/switching at inclusion compared to patients that did not relapse and the CG. This relationship was not found for semantic fluency. Poor performance in inhibition and semantic fluency are prolonged despite symptom reduction in patients with a first episode of MDD. Moreover, although based on a small sample of patients, the present study showed that there may be a relationship between impaired ability in the EF of inhibition/switching and vulnerability for the experience of relapse.

Major depressive disorder is associated with broad impairments on neuropsychological measures of executive function: a meta-analysis and review

Cognitive impairments are now widely acknowledged as an important aspect of major depressive disorder (MDD), and it has been proposed that executive function (EF) may be particularly impaired in patients with MDD. However, the existence and nature of EF impairments associated with depression remain strongly debated. Although many studies have found significant deficits associated with MDD on neuropsychological measures of EF, others have not, potentially due to low statistical power, task impurity, and diverse patient samples, and there have been no recent, comprehensive, meta-analyses investigating EF in patients with MDD. The current meta-analysis uses random-effects models to synthesize 113 previous research studies that compared participants with MDD to healthy control participants on at least one neuropsychological measure of EF. Results of the meta-analysis demonstrate that MDD is reliably associated with impaired performance on neuropsychological measures of EF, with effect sizes ranging from 0.32 to 0.97. Although patients with MDD also have slower processing speed, motor slowing alone cannot account for these results. In addition, some evidence suggests that deficits on neuropsychological measures of EF are greater in patients with more severe current depression symptoms, and those taking psychotropic medications, whereas evidence for effects of age was weaker. The results are consistent with the theory that MDD is associated with broad impairment in multiple aspects of EF. Implications for treatment of MDD and theories of EF are discussed. Future research is needed to establish the specificity and causal link between MDD and EF impairments.

Neurocognitive impairment in adolescent major depressive disorder: state vs. trait illness markers

BACKGROUND

Current treatment outcomes of Major Depressive Disorder (MDD) in adolescents remain suboptimal. Discriminating between state and trait markers of MDD in adolescents would help identify markers that may guide choice of appropriate interventions and help improve longer-term outcome for individuals with the illness.

METHODS

We compared neurocognitive performance in executive function, sustained attention and short-term memory in 20 adolescents with MDD in acute episode (MDDa), 20 previously depressed adolescents in remission (MDDr) and 17 healthy control participants (HC).

RESULTS

There was a group difference that emerged for executive function with increasing task difficulty (p=0.033). MDDa showed impaired executive function, as measured by using more moves to solve 4-move problems on a forward planning task, relative to MDDr and HC (p=0.01, d=0.94 and p=0.015, d=0.77 respectively). MDDa showed more impulsivity as measured by lower response bias (B″) on a sustained attention task than both MDDr and HC (p=0.01, d=0.85 and p=0.008, d=0.49 respectively). Higher impulsivity was associated with more severe depression (r=-0.365, p=0.022) and earlier age of onset of depression (r=0.402, p=0.012) and there was a trend for a correlation between more executive dysfunction and more severe depression (r=0.301 p=0.059) in MDDa and MDDr combined. The three groups did not differ significantly on short-term memory or target detection on the sustained attention task.

LIMITATION

These results need to be replicated in the future with a larger sample size.

CONCLUSION

Executive dysfunction and impulsivity appear to be state-specific markers of MDD in adolescents that are related to depression severity and not present in remission.

Dispositional fear, negative affectivity, and neuroimaging response to visually suppressed emotional faces

"Invisible" stimulus paradigms provide a method for investigating basic affective processing in clinical and non-clinical populations. Neuroimaging studies utilizing continuous flash suppression (CFS) have shown increased amygdala response to invisible fearful versus neutral faces. The current study used CFS in conjunction with functional MRI to test for differences in brain reactivity to visible and invisible emotional faces in relation to two distinct trait dimensions relevant to psychopathology: negative affectivity (NA) and fearfulness. Subjects consisted of college students (N=31) assessed for fear/fearlessness along with dispositional NA. The main brain regions of interest included the fusiform face area (FFA), superior temporal sulcus (STS), and amygdala. Higher NA, but not trait fear, was associated with enhanced response to fearful versus neutral faces in STS and right amygdala (but not FFA), within the invisible condition specifically. The finding that NA rather than fearfulness predicted degree of amygdala reactivity to suppressed faces implicates the input subdivision of the amygdala in the observed effects. Given the central role of NA in anxiety and mood disorders, the current data also support use of the CFS methodology for investigating the neurobiology of these disorders.

Is impairment in cognitive inhibition in the acute phase of major depression irreversible? Results from a 10-year follow-up study

OBJECTIVES

Even though many studies demonstrate cognitive impairment in the acute phase of depression and several studies indicate that this impairment might be long lasting despite symptom reduction and recovery, there is a lack of longitudinal studies on this field with considerable follow-up length. The aim of this study was to investigate whether the impairment observed in cognitive inhibition in the acute phase of depression is reversible or irreversible in a 10-year follow-up assessment.

DESIGN

A longitudinal study of 38 individuals, 19 with recurrent unipolar depression and 19 healthy controls matched for gender, age, and education were included in the study.

METHOD

Cognitive inhibition was investigated using the Stroop test at three different occasions: acute phase, short-term (6 months), and long-term (10 years) follow-up.

RESULTS

The results show that recurrent major depressive disorder patients have a long-lasting impairment in inhibition as measured by the Stroop test in 10-year follow-up. Further there is high consistency in inner group performance suggesting that severe impairment in the acute phase of illness is associated with severe impairment 10 years later despite recovery in the patient group.

CONCLUSIONS

The results show that impairment in cognitive inhibition is long lasting when present in the acute phase of recurrent depression. Impaired cognitive inhibition might be an irreversible vulnerability marker for recurrent depression.

Frontocingulate dysfunction in depression: toward biomarkers of treatment response

Increased rostral anterior cingulate cortex (rACC) activity has emerged as a promising predictor of treatment response in depression, but neither the reliability of this relationship nor the mechanisms supporting it have been thoroughly investigated. This review takes a three-pronged approach to these issues. First, I present a meta-analysis demonstrating that the relationship between resting rACC activity and treatment response is robust. Second, I propose that the rACC plays a key role in treatment outcome because of its 'hub' position in the default network. Specifically, I hypothesize that elevated resting rACC activity confers better treatment outcomes by fostering adaptive self-referential processing and by helping to recalibrate relationships between the default network and a 'task-positive network' that comprises dorsolateral prefrontal and dorsal cingulate regions implicated in cognitive control. Third, I support this hypothesis by reviewing neuropsychological, electrophysiological, and neuroimaging data on frontocingulate dysfunction in depression. The review ends with a discussion of the limitations of current work and future directions.