Neurocognitive impairment in drug-free patients with major depressive disorder

The effects of desvenlafaxine on neurocognitive and work functioning in employed outpatients with major depressive disorder

BACKGROUND

Major depressive disorder (MDD) is associated with staggering personal and economic costs, a major proportion of which stem from impaired psychosocial and occupational functioning. Few studies have examined the impact of depression-related cognitive dysfunction on work functioning. We examined the association between neurocognitive and work functioning in employed patients with MDD.

METHODS

Employed adult outpatients (n=36) with MDD of at least moderate severity (≥23 on the Montgomery Asberg Depression Rating Scale, MADRS) and subjective cognitive complaints completed neurocognitive tests (CNS Vital Signs computerized battery) and validated self-reports of their work functioning (LEAPS, HPQ) before and after 8 weeks of open-label treatment with flexibly-dosed desvenlafaxine 50-100mg/day. Relationships between neurocognitive tests and functional measures were examined using bivariate correlational and multiple regression analyses, as appropriate. An ANCOVA model examined whether significant change in neurocognitive performance, defined as improvement of ≥1SD in the Neurocognition Index (NCI) from baseline to post-treatment, was associated with improved outcomes.

RESULTS

Patients showed significant improvements in depressive symptom, neurocognitive, and work functioning measures following treatment with desvenlafaxine (e.g., MADRS response=77% and MADRS remission=49%). There were no significant correlations between changes in NCI or cognitive domain subscales and changes in MADRS, LEAPS, or HPQ scores. However, patients demonstrating significant improvement in NCI scores (n=11, 29%) had significantly greater improvement in clinical and work functioning outcomes compared to those without NCI improvement.

LIMITATIONS

The limitations of this study include small sample size, lack of a placebo control group, and lack of a healthy comparison group. Our sample also had more years of education and higher premorbid intelligence than the general population.

CONCLUSIONS

There were no significant correlations between changes in neurocognitive and work functioning measures in this study. However, meaningful improvement in neurocognitive functioning with desvenlafaxine was associated with greater improvement in both mood and occupational outcomes. This suggests that addressing cognitive dysfunction may improve clinical and occupational outcomes in employed patients with MDD. However, the relationship between neurocognitive and work functioning in MDD is complex and requires further study.

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.

Visuospatial planning in unmedicated major depressive disorder and bipolar disorder: distinct and common neural correlates

BACKGROUND

Cognitive impairments are an important feature of both remitted and depressed major depressive disorder (MDD) and bipolar disorder (BD). In particular, deficits in executive functioning may hamper everyday functioning. Identifying the neural substrates of impaired executive functioning would improve our understanding of the pathophysiology underlying these disorders, and may eventually aid in discriminating between MDD and BD, which is often difficult during depression and remission. To date, mostly medicated MDD and BD subjects have been investigated, which may have influenced results. Therefore, we investigated executive functioning in medication-free depressed and remitted MDD and BD subjects.

METHOD

We used the Tower of London (ToL) visuospatial planning task to assess behavioural performance and blood oxygen-level dependent responses in 35 healthy controls, 21 remitted MDD, 23 remitted BD, 19 depressed MDD and nine depressed BD subjects.

RESULTS

Visuospatial planning per se was associated with increased frontostriatal activity in depressed BD compared to depressed MDD. In addition, post-hoc analyses indicated that visuospatial planning load was associated with increased parietal activity in depressed compared to remitted subjects, and BD compared to MDD subjects. Task performance did not significantly differ between groups.

CONCLUSIONS

More severely affected, medication-free mood disorder patients require greater parietal activity to perform in visuospatial planning, which may be compensatory to maintain relatively normal performance. State-dependent frontostriatal hyperactivity during planning may be a specific BD characteristic, providing clues for further characterization of differential pathophysiology in MDD v. BD. This could potentially provide a biomarker to aid in the differentiation of these disorders.

A confirmatory factor analysis of the MATRICS consensus cognitive battery in severe mental illness

BACKGROUND

A recent factor analysis of Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) Consensus Cognitive Battery (MCCB) data in a sample of schizophrenia-spectrum patients described a three factor model representing processing speed, attention/working memory, and learning; the social cognition measure was excluded from the analysis. The current analyses sought to replicate a three factor structure of the MCCB in a larger, more diagnostically diverse sample of participants.

METHODS

Confirmatory factor analyses were performed to evaluate the factor structure of the MCCB in 300 outpatients with severe mental illness (54.3% schizophrenia-spectrum diagnoses) who were participants in three studies of cognitive remediation. Exploratory analyses were conducted to evaluate the concurrent prediction of symptoms from MCCB factor scores.

RESULTS

The three factor structure of the MCCB demonstrated stronger model fit (χ(2)=14.53, p=0.75, SRMR=0.02, RMSEA=0.0, CFI=1.00, NNFI=1.01) than the unifactoral structure. Poorer cognitive performance across all three MCCB factors was significantly correlated with more severe overall and disorganization symptoms from the PANSS and BPRS, and less severe affective symptoms (e.g., depression, anxiety) in the overall sample.

CONCLUSIONS

A three factor structure of the MCCB-composed of processing speed, attention/working memory, and learning-was replicated in a heterogeneous sample of persons with severe mental illness. Cognitive performance on the MCCB factors is associated with clinical symptoms.

Predictors of neurocognitive impairment at 2years after a first-episode major depressive disorder

BACKGROUND

Neurocognitive impairment is a contributor to major depressive disorder (MDD). However, MDD patients show great variability in the level and course of deficits. The present longitudinal study was to identify predictors of neurocognitive impairment in first-episode MDD patients.

METHODS

Neurocognitive performance was analyzed in a cohort of 100 patients at 2years after a first-episode MDD. Subgroups, deficit type vs. non-deficit type, were compared on baseline clinical, neuropsychological, premorbid and sociodemographic characteristics. The analysis was performed using the multivariate logistic regression to obtain a model for neurocognitive impairment determination. The predicted probabilities of multivariate logistic regression were analyzed using receiver operating characteristic (ROC) curve.

RESULTS

Fifty-two percent of MDD participants presented general neurocognitive impairment. The regression analyses demonstrated that clinical and sociodemographic characteristics were not predictive variables. A model composed of processing speed, executive function, and attention, dexterity correctly classified 85.8% of the MDD patients with deficit type. ROC curve indicated that the changes of these three cognitions could identify MDD with deficit type from MDD with non-deficit type. In addition, ROC curve also indicated that processing speed and executive function could identify MDD from CN subjects. Finally, processing speed performance was negatively correlated with Hamilton Depression Scale scores in both MDD with deficit and non-deficit type.

CONCLUSION

The present study provides novel insights on frequency and neurocognitive profile of subtypes of patients showing impairment. Our results suggest that processing speed impairment is a trait dimension of the disorder related to specific cognitive dysfunctions and the severity of depression.

Cannabinoids reverse the effects of early stress on neurocognitive performance in adulthood

Early life stress (ES) significantly increases predisposition to psychopathologies. Cannabinoids may cause cognitive deficits and exacerbate the effects of ES. Nevertheless, the endocannabinoid system has been suggested as a therapeutic target for the treatment of stress- and anxiety-related disorders. Here we examined whether cannabinoids administered during "late adolescence" (extensive cannabis use in humans at the ages 18-25) could reverse the long-term adverse effects of ES on neurocognitive function in adulthood. Male and female rats were exposed to ES during post-natal days (P) 7-14, injected with the cannabinoid CB1/2 receptor agonist WIN55,212-2 (WIN; 1.2 mg/kg, i.p.) for 2 wk during late adolescence (P45-60) and tested in adulthood (P90) for working memory, anxiety, and alterations in CB1 receptors (CB1r), and glucocorticoid receptors (GRs) in the stress circuit [hippocampus, prefrontal cortex (PFC), and basolateral amygdala (BLA)]. ES males and females exhibited impaired performance in short-term memory in adulthood in the spatial location and social recognition tasks; males were also impaired in the novel object recognition task. WIN administered during late adolescence prevented these stress-induced impairments and reduced anxiety levels. WIN normalized the ES-induced up-regulation in PFC-GRs and CA1-CB1r in females. In males, WIN normalized the ES-induced up-regulation in PFC-GR and down-regulation in BLA-CB1r. There is a crucial role of the endocannabinoid system in the effects of early life stress on behavior at adulthood. Differences in recognition memory and in the expression of GRs and CB1r in the fear circuit suggest sex differences in the mechanism underlying coping with stress.

The serotonergic 5-HT4 receptor: A unique modulator of hippocampal synaptic information processing and cognition

Serotonin (5-hydroxytryptamine, 5-HT) contributes in multifarious ways to the regulation of brain function, spanning key aspects such as the sleep-wake cycle, appetite, mood and mental health. The 5-HT receptors comprise seven receptor families (5-HT_1-7) that are further subdivided into 14 receptor subtypes. The role of the 5-HT receptor in the modulation of neuronal excitability has been well documented. Recently, however, it has become apparent that the 5-HT₄ receptor may contribute significantly to cognition and regulates less ostensible aspects of brain function: it engages in metaplastic regulation of synaptic responsiveness in key brain structures such as the hippocampus, thereby specifically promoting persistent forms of synaptic plasticity, and influences the direction of change in synaptic strength in selected hippocampal subfields. This highly specific neuromodulatory control by the 5-HT₄ receptor may in turn explain the reported role for this receptor in hippocampus-dependent cognition. In this review article, we describe the role of the 5-HT₄ receptor in hippocampal function, and describe how this receptor plays a unique and highly specialised role in synaptic information storage and cognition.

Informed consent in implantable BCI research: identification of research risks and recommendations for development of best practices

OBJECTIVE

Implantable brain-computer interface (BCI) research promises improvements in human health and enhancements in quality of life. Informed consent of subjects is a central tenet of this research. Rapid advances in neuroscience, and the intimate connection between functioning of the brain and conceptions of the self, make informed consent particularly challenging in BCI research. Identification of safety and research-related risks associated with BCI devices is an important step in ensuring meaningful informed consent.

APPROACH

This paper highlights a number of BCI research risks, including safety concerns, cognitive and communicative impairments, inappropriate subject expectations, group vulnerabilities, privacy and security, and disruptions of identity.

MAIN RESULTS

Based on identified BCI research risks, best practices are needed for understanding and incorporating BCI-related risks into informed consent protocols.

SIGNIFICANCE

Development of best practices should be guided by processes that are: multidisciplinary, systematic and transparent, iterative, relational and exploratory.

Imbalance in subregional connectivity of the right temporoparietal junction in major depression

Major depressive disorder (MDD) involves impairment in cognitive and interpersonal functioning. The right temporoparietal junction (RTPJ) is a key brain region subserving cognitive-attentional and social processes. Yet, findings on the involvement of the RTPJ in the pathophysiology of MDD have so far been controversial. Recent connectivity-based parcellation data revealed a topofunctional dualism within the RTPJ, linking its anterior and posterior part (aRTPJ/pRTPJ) to antagonistic brain networks for attentional and social processing, respectively. Comparing functional resting-state connectivity of the aRTPJ and pRTPJ in 72 MDD patients and 76 well-matched healthy controls, we found a seed (aRTPJ/pRTPJ) × diagnosis (MDD/controls) interaction in functional connectivity for eight regions. Employing meta-data from a large-scale neuroimaging database, functional characterization of these regions exhibiting differentially altered connectivity with the aRTPJ/pRTPJ revealed associations with cognitive (dorsolateral prefrontal cortex, parahippocampus) and behavioral (posterior medial frontal cortex) control, visuospatial processing (dorsal visual cortex), reward (subgenual anterior cingulate cortex, medial orbitofrontal cortex, posterior cingulate cortex), as well as memory retrieval and social cognition (precuneus). These findings suggest that an imbalance in connectivity of subregions, rather than disturbed connectivity of the RTPJ as a whole, characterizes the connectional disruption of the RTPJ in MDD. This imbalance may account for key symptoms of MDD in cognitive, emotional, and social domains. Hum Brain Mapp 37:2931-2942, 2016. © 2016 Wiley Periodicals, Inc.

Abnormal functional connectivity density in first-episode, drug-naive adult patients with major depressive disorder

Previous studies have found evidence of brain functional connectivity (FC) changes with pre-selected region-of-interest (ROI) method in major depressive disorder (MDD). However, these studies could not completely exclude personal inequality when drawing ROIs manually and did not measure the total number of FC for each voxel. Here, we firstly applied functional connectivity density (FCD) mapping, a voxel-based analysis to locate the hubs with amount changes of FC between 22 first-episode, drug-naive adult MDD patients and 22 healthy control (HC) subjects. Both short-range (local) FCD and long-range (distal) FCD were measured. The relationships of FCD changes with Hamilton Depression Rating Scale (HAMD) scores and illness duration were also explored. Compared with the HC group, MDD patients showed significantly decreased short-range FCD in the left superior temporal gyrus (STG), the right orbital frontal cortex (OFC) and bilateral precuneus, while significantly decreased long-range FCD was found in bilateral middle occipital gyrus (MOG), superior occipital gyrus (SOG) and right calcarine. These results firstly demonstrated both local and distal alterations of connection amount at voxel level, and highlighted that the OFC, the precuneus, the STG and the visual cortex were important brain network hubs for first-episode, drug-naive adult MDD patients. Our findings were complementary for previous structural and functional studies in MDD patients, and provided new evidence of the dysfunction of connection hubs in the pathophysiology of MDD at voxel level.

Assessing anhedonia in depression: Potentials and pitfalls

The resurgence of interest in anhedonia within major depression has been fuelled by clinical trials demonstrating its utility in predicting antidepressant response as well as recent conceptualizations focused on the role and manifestation of anhedonia in depression. Historically, anhedonia has been understood as a "loss of pleasure", yet neuropsychological and neurobiological studies reveal a multifaceted reconceptualization that emphasizes different facets of hedonic function, including desire, effort/motivation, anticipation and consummatory pleasure. To ensure generalizability across studies, evaluation of the available subjective and objective methods to assess anhedonia is necessary. The majority of research regarding anhedonia and its neurobiological underpinnings comes from preclinical research, which uses primary reward (e.g. food) to probe hedonic responding. In contrast, behavioural studies in humans primarily use secondary reward (e.g. money) to measure many aspects of reward responding, including delay discounting, response bias, prediction error, probabilistic reversal learning, effort, anticipation and consummatory pleasure. The development of subjective scales to measure anhedonia has also increased in the last decade. This review will assess the current methodology to measure anhedonia, with a focus on scales and behavioural tasks in humans. Limitations of current work and recommendations for future studies are discussed.

Cognitive Dysfunction in Major Depressive Disorder. A Translational Review in Animal Models of the Disease

Major Depressive Disorder (MDD) is the most common psychiatric disease, affecting millions of people worldwide. In addition to the well-defined depressive symptoms, patients suffering from MDD consistently complain about cognitive disturbances, significantly exacerbating the burden of this illness. Among cognitive symptoms, impairments in attention, working memory, learning and memory or executive functions are often reported. However, available data about the heterogeneity of MDD patients and magnitude of cognitive symptoms through the different phases of MDD remain difficult to summarize. Thus, the first part of this review briefly overviewed clinical studies, focusing on the cognitive dysfunctions depending on the MDD type. As animal models are essential translational tools for underpinning the mechanisms of cognitive deficits in MDD, the second part of this review synthetized preclinical studies observing cognitive deficits in different rodent models of anxiety/depression. For each cognitive domain, we determined whether deficits could be shared across models. Particularly, we established whether specific stress-related procedures or unspecific criteria (such as species, sex or age) could segregate common cognitive alteration across models. Finally, the role of adult hippocampal neurogenesis in rodents in cognitive dysfunctions during MDD state was also discussed.

Differential Resting State Connectivity Patterns and Impaired Semantically Cued List Learning Test Performance in Early Course Remitted Major Depressive Disorder

OBJECTIVES

There is a well-known association between memory impairment and major depressive disorder (MDD). Additionally, recent studies are also showing resting-state functional magnetic resonance imaging (rsMRI) abnormalities in active and remitted MDD. However, no studies to date have examined both rs connectivity and memory performance in early course remitted MDD, nor the relationship between connectivity and semantically cued episodic memory.

METHODS

The rsMRI data from two 3.0 Tesla GE scanners were collected from 34 unmedicated young adults with remitted MDD (rMDD) and 23 healthy controls (HCs) between 18 and 23 years of age using bilateral seeds in the hippocampus. Participants also completed a semantically cued list-learning test, and their performance was correlated with hippocampal seed-based rsMRI. Regression models were also used to predict connectivity patterns from memory performance.

RESULTS

After correcting for sex, rMDD subjects performed worse than HCs on the total number of words recalled and recognized. rMDD demonstrated significant in-network hypoactivation between the hippocampus and multiple fronto-temporal regions, and multiple extra-network hyperconnectivities between the hippocampus and fronto-parietal regions when compared to HCs. Memory performance negatively predicted connectivity in HCs and positively predicted connectivity in rMDD. Conclusions Even when individuals with a history of MDD are no longer displaying active depressive symptoms, they continue to demonstrate worse memory performance, disruptions in hippocampal connectivity, and a differential relationship between episodic memory and hippocampal connectivity.

Increased miR-132 level is associated with visual memory dysfunction in patients with depression

BACKGROUND

Impaired visual memory seems to be a core feature of depression, while increased microRNA-132 (miR-132) levels have been widely reported in depression patients. The authors aimed to explore the relationship between miR-132 changes and visual memory deficits in unmedicated patients with major depressive disorder (MDD).

PATIENTS AND METHODS

A total of 62 medication-free MDD patients and 73 matched healthy controls (HCs) were tested for miR-132 expression level in peripheral blood using quantitative real-time polymerase chain reaction. We used a computerized neurocognitive task from the Cambridge Neuropsychological Test Automated Battery (CANTAB) - pattern recognition memory (PRM) task - as a measurement of visual memory. The relationship between visual memory, miR-132 expression level, and clinical symptoms was explored in patients with MDD.

RESULTS

Upregulated miR-132 expression levels were seen in MDD patients but not in HCs. Two-sample t-tests showed that MDD patients had decreased visual memory, mainly memory delayed compared to that of HCs. Correlation analyses revealed that in MDD patients, increased miR-132 expression levels were significantly correlated with visual memory as measured by the CANTABPRM. Hamilton Rating Scale for Anxiety scores were negatively correlated with PRM - number correct (immediate) and PRM - percent correct (immediate).

LIMITATIONS

The main limitations were missing data and lack of follow-up studies.

CONCLUSION

Our study suggests that increased miR-132 expression levels were associated with visual memory deficits, which may underlie the pathophysiology of MDD. In individuals with depression, immediate visual memory defects were positively correlated with anxiety symptoms.

The effect of daily small text message reminders for medicine compliance amongst young people connected with the outpatient department for child and adolescent psychiatry. A controlled and randomized investigation

BACKGROUND

Many patients with psychiatric illnesses have difficulty maintaining medication over time. Many take their medicine irregularly and studies show that it is the most vulnerable patients who have the greatest problems adhering to treatment. Often only 50% are still under medical treatment after 6 months.

AIM

In this study we investigated whether text message reminders could improve medicine compliance amongst vulnerable young people with psychiatric disorders who were being treated in the outpatient department for child and adolescent psychiatry and who either are under or were to commence medicinal treatment.

METHODS

This study was conducted as a randomized controlled trial including all non-acute referrals to an outpatient department for adolescent psychiatry within a group aged 15-20 years starting medical treatment. The patients were followed until the end of their treatment, for a minimum of 3 months. To enhance medicine compliance, text messages were sent daily to one group. No message was sent to the other group.

RESULTS

Compliance was not associated with text message intervention in any of the drug interventions. The effect size was calculated to 0.3013, which is low and therefore indicates a weak association between text message and compliance. The power in this study was calculated to 0.3539, which is also low and therefore the likelihood of finding significant association is low.

CONCLUSION

This study does not show increased medicine compliance from the text message intervention group. The conclusion of this study is that it is essential that significant resources are spent preparing and testing a text message strategy.

The neurocognitive profile of mood disorders - a review of the evidence and methodological issues

OBJECTIVES

Cognitive abnormalities are an established part of the symptomatology of mood disorders. However, questions still exist regarding the exact profile of these deficits in terms of the domains most affected, their origins, and their relationship to clinical subtypes. This review aims to examine the current state of the evidence and to examine ways in which the field may be advanced.

METHODS

Studies examining cognitive function in bipolar disorder (BD) and unipolar major depression (MDD) were examined. Given the number and variability of such studies, particular attention was paid to meta-analyses and to meta-regression analyses which examined the possible mediators of cognitive impairment.

RESULTS

Meta-analyses are available for MDD and BD in both depression and euthymia. Several analyses examine mediators. Results do not support the presence of domain specific deficits but rather a moderate deficit across a range of domains in BD and in MDD. The data on clinical mediators is inconsistent, even with regard to the effect of mood state.

CONCLUSIONS

A two-tiered approach, with the broad-based application of standardized measures on a large-scale, and the refined application of theoretically driven experimental development would significantly further our understanding of neurocognitive processing in mood disorder.

Neurocognitive intra-individual variability in mood disorders: effects on attentional response time distributions

BACKGROUND

Attentional impairment is a core cognitive feature of major depressive disorder (MDD) and bipolar disorder (BD). However, little is known of the characteristics of response time (RT) distributions from attentional tasks. This is crucial to furthering our understanding of the profile and extent of cognitive intra-individual variability (IIV) in mood disorders.

METHOD

A computerized sustained attention task was administered to 138 healthy controls and 158 patients with a mood disorder: 86 euthymic BD, 33 depressed BD and 39 medication-free MDD patients. Measures of IIV, including individual standard deviation (iSD) and coefficient of variation (CoV), were derived for each participant. Ex-Gaussian (and Vincentile) analyses were used to characterize the RT distributions into three components: mu and sigma (mean and standard deviation of the Gaussian portion of the distribution) and tau (the 'slow tail' of the distribution).

RESULTS

Compared with healthy controls, iSD was increased significantly in all patient samples. Due to minimal changes in average RT, CoV was only increased significantly in BD depressed patients. Ex-Gaussian modelling indicated a significant increase in tau in euthymic BD [Cohen's d = 0.39, 95% confidence interval (CI) 0.09-0.69, p = 0.011], and both sigma (d = 0.57, 95% CI 0.07-1.05, p = 0.025) and tau (d = 1.14, 95% CI 0.60-1.64, p < 0.0001) in depressed BD. The mu parameter did not differ from controls.

CONCLUSIONS

Increased cognitive variability may be a core feature of mood disorders. This is the first demonstration of differences in attentional RT distribution parameters between MDD and BD, and BD depression and euthymia. These data highlight the utility of applying measures of IIV to characterize neurocognitive variability and the great potential for future application.

WITHDRAWN: Antiglucocorticoid treatments for mood disorders

In the original submission two of the authors declared a filing of a pharmaceutical patent. This does not comply with Cochrane's Commercial Sponsorship Policy. The remaining authors are unable to update the review at this time and have therefore withdrawn it from the Cochrane library.

The editorial group responsible for this previously published document have withdrawn it from publication.

Posttraumatic Psychological Symptoms are Associated with Reduced Inhibitory Control, not General Executive Dysfunction

Although there is mounting evidence that greater PTSD symptoms are associated with reduced executive functioning, it is not fully understood whether this association is more global or specific to certain executive function subdomains, such as inhibitory control. We investigated the generality of the association between PTSD symptoms and executive function by administering a broad battery of sensitive executive functioning tasks to a cohort of returning Operation Enduring Freedom/Operation Iraqi Freedom Veterans with varying PTSD symptoms. Only tasks related to inhibitory control explained significant variance in PTSD symptoms as well as symptoms of depression, while measures of working memory, measures of switching, and measures simultaneously assessing multiple executive function subdomains did not. Notably, the two inhibitory control measures that showed the highest correlation with PTSD and depressive symptoms, measures of response inhibition and distractor suppression, explained independent variance. These findings suggest that greater posttraumatic psychological symptoms are not associated with a general decline in executive functioning but rather are more specifically related to stopping automatic responses and resisting internal and external distractions.

A working memory training to decrease rumination in depressed and anxious individuals: a double-blind randomized controlled trial

BACKGROUND

Rumination is one of the hallmark characteristics of both anxiety disorders and depression, and has been linked to deficient executive functioning, particularly working memory (WM). Previous findings show that working memory capacity can be increased through training.

METHODS

The current study explored whether an adaptive stand-alone WM training could increase WMC and consequently reduce rumination, anxiety and depression by means of a double-blind randomized controlled trial in a sample of 98 patients with symptoms of anxiety and/or depression.

RESULTS

No positive effect of training on WMC was found. In addition, the results show that a WM training was not associated with a reduction of rumination, depression, nor anxiety.

LIMITATIONS

The high drop-out rate in both groups (20.11% from pre- to post-training) and the overrepresentation of men and use of anti-depressants in the placebo group might have influenced the results. Furthermore, expectations and perceptions about the training might have interacted with performance on WM tasks.

CONCLUSIONS

Overall, results show that a stand-alone WM training in patients with symptoms of anxiety and/or depression does not result in reduced rumination nor in reduced symptoms of depression and anxiety. We discuss potential explanations for these findings.

Effects of remission speed and improvement of cognitive functions of depressed patients

Major depressive disorder (MDD) presents neuropsychological alterations which improve after the treatment, but it might be mediated by clinical variables. Our goal is to study whether the speed of remission of MDD bears any relation to the improvement of the patients' cognitive functioning after a successful treatment. We carried out clinical and neuropsychological assessments of 51 patients with MDD. After these procedures they underwent a 24-week treatment with fluoxetine, and were assessed again with the same battery used prior to treatment. They were arranged into three groups according to how rapid their symptoms remitted. The patients with a rapid remission presented improvements in working memory, speed of information processing, and some executive functions, unlike the other groups. Rapid remitters also improved in episodic memory and executive functions more than the other patients.

Auditory selective attention in adolescents with major depression: An event-related potential study

BACKGROUND

Major depression (MD) is associated with deficits in selective attention. Previous studies in adults with MD using event-related potentials (ERPs) reported abnormalities in the neurophysiological correlates of auditory selective attention. However, it is yet unclear whether these findings can be generalized to MD in adolescence. Thus, the aim of the present ERP study was to explore the neural mechanisms of auditory selective attention in adolescents with MD.

METHODS

24 male and female unmedicated adolescents with MD and 21 control subjects were included in the study. ERPs were collected during an auditory oddball paradigm.

RESULTS

Depressive adolescents tended to show a longer N100 latency to target and non-target tones. Moreover, MD subjects showed a prolonged latency of the P200 component to targets. Across groups, longer P200 latency was associated with a decreased tendency of disinhibited behavior as assessed by a behavioral questionnaire.

LIMITATIONS

To be able to draw more precise conclusions about differences between the neural bases of selective attention in adolescents vs. adults with MD, future studies should include both age groups and apply the same experimental setting across all subjects.

CONCLUSIONS

The study provides strong support for abnormalities in the neurophysiolgical bases of selective attention in adolecents with MD at early stages of auditory information processing. Absent group differences in later ERP components reflecting voluntary attentional processes stand in contrast to results reported in adults with MD and may suggest that adolescents with MD possess mechanisms to compensate for abnormalities in the early stages of selective attention.

Cognitive function after clinical remission in patients with melancholic and non-melancholic depression: a 6 month follow-up study

BACKGROUND

Cognitive symptoms are core symptoms with an impact on functioning in depression. Remission is considered as the main objective of the management and treatment of depression. This study was aimed to compare cognitive performance between melancholic (MelD) and non-melancholic depression (NMelD) and to determine whether these cognitive alterations remain after clinical remission.

METHODS

We performed a 6 month follow-up study of 88 melancholic and non-melancholic depressive patients. Sociodemographic and clinical characteristics were recorded. Depression was examined using the Hamilton Depression Rating Scale and the CORE Index for Melancholia. Cognitive performance was assessed with the Trail Making Test (TMT), the Digit Span subtest of the WAIS-III, Stroop Colour Word Test (SCWT), the Tower of London (TOL DX), the Controlled Oral Word Association Test (FAS), Semantic Verbal Fluency and Finger Tapping Test (FTT).

RESULTS

MelD patients show worse performance than N-MelD at baseline, with significant differences at Digit Span subtest of WAIS Part I and Part II, SCWT Part I and Part II, TOL DX, Total Problem Solving, Total Execution Time and FTT- Preferred hand. Cognitive impairment remains at six months follow-up after clinical remission in MelD. In the comparison between remitted and non-remitted patients, cognitive impairment in Trail Making Test Part B and Verbal and Semantic Fluency (Animals) remains after clinical remission in MelD group but not in non-melancholic patients.

LIMITATIONS

The use of psychopharmacological treatment and the small sample of melancholic patients.

CONCLUSIONS

Patients with MelD do not improve cognitive performance despite clinical remission compared with remitted NMelD patients. The persistence of some cognitive dysfunctions in MelD remitted patients could represent a trait marker of a different depressive subtype and not be secondary to disease severity.

Interactive effects of neurocognitive impairment and substance use on antiretroviral non-adherence in HIV disease

While numerous studies have established the adverse independent effects of clinical conditions including neurocognitive dysfunction, psychiatric illness, and substance abuse/dependence on medication adherence among HIV-infected adults, fewer have studied their interactive effects. The current study examined this issue among 204 HIV-infected participants based upon current neurocognitive functioning and DSM-IV-diagnosed psychiatric illness and current substance abuse or dependence. Results confirmed that participants with any of these risk factors demonstrated poorer adherence than individuals with no risk factors. A neurocognitive status × substance abuse/dependence interaction was also identified such that participants with impaired neurocognition and a co-occurring substance abuse/dependence diagnosis demonstrated the poorest adherence. Results confirm the deleterious impact of these risk factors in isolation and also identify a specific interactive effect for individuals with comorbid neurocognitive impairment and a substance abuse/dependence disorder. Findings highlight the need for interventions that simultaneously address these problems.

A quantitative meta-analysis of neurocognitive functioning in posttraumatic stress disorder

Posttraumatic stress disorder (PTSD) is associated with regional alterations in brain structure and function that are hypothesized to contribute to symptoms and cognitive deficits associated with the disorder. We present here the first systematic meta-analysis of neurocognitive outcomes associated with PTSD to examine a broad range of cognitive domains and describe the profile of cognitive deficits, as well as modifying clinical factors and study characteristics. This report is based on data from 60 studies totaling 4,108 participants, including 1,779 with PTSD, 1,446 trauma-exposed comparison participants, and 895 healthy comparison participants without trauma exposure. Effect-size estimates were calculated using a mixed-effects meta-analysis for 9 cognitive domains: attention/working memory, executive functions, verbal learning, verbal memory, visual learning, visual memory, language, speed of information processing, and visuospatial abilities. Analyses revealed significant neurocognitive effects associated with PTSD, although these ranged widely in magnitude, with the largest effect sizes in verbal learning (d = -.62), speed of information processing (d = -.59), attention/working memory (d = -.50), and verbal memory (d =-.46). Effect-size estimates were significantly larger in treatment-seeking than community samples and in studies that did not exclude participants with attention-deficit/hyperactivity disorder, and effect sizes were affected by between-group IQ discrepancies and the gender composition of the PTSD groups. Our findings indicate that consideration of neuropsychological functioning in attention, verbal memory, and speed of information processing may have important implications for the effective clinical management of persons with PTSD. Results are further discussed in the context of cognitive models of PTSD and the limitations of this literature.

The effect of bupropion XL and escitalopram on memory and functional outcomes in adults with major depressive disorder: results from a randomized controlled trial

Decrements in cognitive function are a common feature of Major Depressive Disorder (MDD), and whether distinct classes of antidepressants differentially affect memory in these individuals has not been sufficiently evaluated. In this study we sought to determine the effect of escitalopram and bupropion XL on memory and psychosocial function. Forty-one individuals (18-50 years) with MDD were enrolled in an 8-week, double-blind, double-dummy, randomized controlled comparative trial of bupropion XL and escitalopram. Thirty-six participants completed pre and post memory assessments. Verbal, non-verbal and working memory were evaluated with a comprehensive neuropsychological battery. Psychosocial function was assessed with the Sheehan Disability Scale and Endicott Work Productivity Scale. Escitalopram and bupropion XL significantly improved immediate as well as delayed verbal and nonverbal memory, global function (all p≤0.001), and work productivity (p=0.045), with no significant between-group differences. Improvement in immediate verbal memory exerted a direct influence on improvement in global function (p=0.006). Treatment with either escitalopram or bupropion XL was associated with improvement in memory and psychosocial function in adults with MDD.

Executive Function Deficits in Daily Life Prospectively Predict Increases in Depressive Symptoms

Executive function (EF) deficits are associated with depression. Given that few prospective studies have been conducted, it is unclear whether deficits contribute to depression or result from it. The present study examined whether self-reported EF prospectively predicted worsening of depression symptoms. Time 1 (T1) shifting, inhibition, and working memory (WM) were assessed in relation to T1 and time 2 (T2) depressive symptoms in participants pre-selected to range in risk for depression. Analyses indicated that poorer EF at T1 predicted increases in depressive symptoms and furthermore that this relationship was specific to WM. In contrast, a bidirectional relationship was not evident, as depressive symptoms did not prospectively predict changes in EF. Finally, T1 EF accounted for T2 depressive symptoms beyond two well established predictors of depression: depressive symptoms at T1 and rumination at T2. These findings suggest that EF deficits play an active role in depression onset, maintenance, and/or recurrence.

Transcranial bright light treatment via the ear canals in seasonal affective disorder: a randomized, double-blind dose-response study

BACKGROUND

Bright light treatment is effective for seasonal affective disorder (SAD), although the mechanisms of action are still unknown. We investigated whether transcranial bright light via the ear canals has an antidepressant effect in the treatment of SAD.

METHODS

During the four-week study period, 89 patients (67 females; 22 males, aged 22-65, mean ± SD age: 43.2 ± 10.9 years) suffering from SAD were randomized to receive a 12-min daily dose of photic energy of one of three intensities (1 lumen/0.72 mW/cm(2); 4 lumens/2.881 mW/cm(2); 9 lumens/6.482 mW/cm(2)) via the ear canals. The light was produced using light-emitting diodes. The severity of depressive symptoms was assessed with the Hamilton Depression Rating Scale - Seasonal Affective Disorder (SIGH-SAD), the Hamilton Anxiety Rating Scale (HAMA), and the Beck Depression Inventory (BDI). Cognitive performance was measured by the Trail Making Test (TMT). The within-group and between-group changes in these variables throughout the study were analysed with a repeated measures analysis of variance (ANOVA), whereas gender differences at baseline within the light groups were analysed using Student's t-tests.

RESULTS

Patients in all three groups showed significant decreases in their BDI, HAMA, and SIGH-SAD scores. Response rates, i.e., an at least 50% decrease of symptoms as measured by the BDI, were 74%-79% in the three treatment groups. Corresponding variations for the SIGH-SAD and the HAMA were 35-45% and 47-62%, respectively. No intensity-based dose-response relationships in the improvement of anxiety and depressive symptoms or cognitive performance between treatment groups were observed. Approximately one in four patients experienced mild adverse effects, of which the most common were headache, insomnia, and nausea.

CONCLUSIONS

These results suggests that transcranial bright light treatment may have antidepressant and anxiolytic effect in SAD patients, as both self- and psychiatrist-rated depressive and anxiety symptoms decreased in all treatment groups. These improvements are comparable to findings of earlier bright light studies that used conventional devices. The lack of dose response may be due to a saturation effect above a certain light intensity threshold. Further studies on the effects of transcranial bright light with an adequate placebo condition are needed.

TRIAL REGISTRATION

NCT01293409, ClinicalTrials.gov.

Neuropsychological functioning in adolescents and young adults with major depressive disorder--a review

While neuropsychological dysfunction is a contributor to major depressive disorder (MDD) in adult MDD, little is known about neuropsychological function in MDD during adolescence and early adulthood. The aim of this review is to evaluate literature on neuropsychological function in this young age group. A database search of Medline, the Cochrane database and PsycInfo was conducted. Inclusion/exclusion criteria yielded seven case-control studies on neuropsychological functioning in MDD (12-25 years of age) published since 1995. Effect sizes were calculated. Results show a broader range of statistically significant neuropsychological deficits in MDD compared to controls in the cognitive domains of executive function (EF), working memory (WM), psychomotor and processing speed (PPS), verbal fluency (VF) and visual (-spatial) memory (VM). Most convincingly, three out of four studies investigating WM and three out of four studies investigating PPS found statistically significant impairments in MDD with varying effect sizes. EF deficits were reported only in three out of seven studies with small, medium and large effect sizes. While some evidence was found for impaired VM and VF, no evidence was observed for attention and verbal learning and memory; however, these domains have been less extensively studied. Further research is required to broaden the study base.

Comparative study of cognitive impairment between medicated and medication-free patients with remitted major depression: class-specific influence by tricyclic antidepressants and newer antidepressants

Patients with major depressive disorder (MDD) are known to present with cognitive deficits; however, the presence of these deficits in the remitted state have been inconsistent. One of the most important factors potentially contributing to inconsistencies between studies may be the influence of medications. To explore the influence of antidepressants on cognitive performance in remitted MDD, we evaluated memory and executive functions using Wechsler Memory Scale-Revised and Stroop Color and Word Test, and compared performance among 50 medicated (29 treated with tricyclic antidepressants [TCA], 21 treated with selective serotonin reuptake inhibitors or serotonin noradrenalin reuptake inhibitors) and 19 medication-free MDD patients and 31 controls. The results showed that all 3 MDD groups had significantly lower performance for verbal memory compared with controls. Both medicated groups showed significantly lower performance for visual memory compared with controls; however, the medication-free group did not differ from controls. For the executive function, only the TCA group showed a significantly lower performance compared with controls. These results suggest that cognitive impairment remained even in remitted patients with MDD, however, part of this impairment may be influenced by class-specific antidepressant side effects.

Effects of tobacco smoking on neuropsychological function in schizophrenia in comparison to other psychiatric disorders and non-psychiatric controls

BACKGROUND AND OBJECTIVES

Compared to the general population cigarette smoking prevalence is elevated in psychiatric disorders such as schizophrenia (SZ), bipolar disorder (BD), and major depressive disorder (MDD). These disorders are also associated with neurocognitive impairments. Cigarette smoking is associated with improved cognition in SZ. The effects of smoking on cognition in BD and MDD are less well studied.

METHODS

We used a cross-sectional design to study neuropsychological performance in these disorders as a function of smoking status. Subjects (N = 108) were SZ smokers (n = 32), SZ non-smokers (n = 15), BD smokers (n = 10), BD non-smokers (n = 6), MDD smokers (n = 6), MDD non-smokers (n = 10), control smokers (n = 12), and control non-smokers (n = 17). Participants completed a neuropsychological battery; smokers were non-deprived.

RESULTS

SZ subjects performed significantly worse than controls in select domains, while BD and MDD subjects did not differ from controls. Three verbal memory outcomes were improved in SZ smokers compared with non-smokers; smoking status did not alter performance in BD or MDD.

CONCLUSIONS AND SCIENTIFIC SIGNIFICANCE

These data suggest that smoking is associated with neurocognitive improvements in SZ, but not BD or MDD. Our data may suggest specificity of cigarette-smoking modulation of neurocognitive deficits in SZ.

Neurocognitive impairment of mental rotation in major depressive disorder: evidence from event-related brain potentials

Mental rotation performance may be used as an index of mental slowing or bradyphrenia and may reflect speed of motor preparation. Previous studies suggest that major depressive disorder (MDD) presents correlates of impaired behavioral performance for mental rotation and psychomotor disturbance. Very little is known about the electrophysiological mechanism underlying this deficit. The present study was the first to investigate the event-related brain potential (ERP) correlates of mental rotation and their mental slowing or bradyphrenia in MDD. ERPs were recorded while we tested 25 MDD patients and 26 healthy controls by evaluating the performance of MDD patients on hand and letter rotation tasks at different orientations, and their 400-to-600-msec time window was measured and analyzed for latencies and peak amplitudes over the electrodes. First, individuals with MDD were slower and made more errors in mentally rotating hands and letters than healthy controls did, and individuals with MDD exhibited a greater difference in response times and errors than controls did between hands and letters. Second, the mean peak amplitude was significantly lower and the mean latency was significantly longer in the 400-to-600-msec time window at the parietal site in the hand tasks in MDD patients than in controls, but this was not seen in the letter task, with only lower mean peak amplitude. MDD patients present the absence of a typical mental rotation function for the amplitude of the rotation-related negativity in the hand and letter tasks. Third, the scalp activity maps in MDD patients exhibited the absence of activation in the left parietal site for the mental rotation of hands, as shown in healthy participants. In contrast, their brain activation for the letter task was similar to those of healthy participants. These data suggest that mental imagery of hands and letters relies on different cognitive and neural mechanisms and indicate that the left posterior parietal lobe is a necessary structure for mental transformations of human hands. Importantly, MDD deficits were more seriously present specific to the hands than the letters. Such impairment may also be an important and possibly defining marker of MDD in particular.

Cognitive impairment in depression: a systematic review and meta-analysis

BACKGROUND

This review aimed to address the question of whether cognitive impairment should be considered a core feature of depression that may be a valuable target for treatment.

METHOD

We conducted a systematic review and meta-analysis of cognitive function, assessed with a single neuropsychological test battery, the Cambridge Neuropsychological Test Automated Battery (CANTAB), in patients with depression during symptomatic and remitted states. Inclusion of studies comparing patients remitted from depression and controls enabled us to investigate whether cognitive impairment persists beyond episodes of low mood in depression.

RESULTS

Our meta-analysis revealed significant moderate cognitive deficits in executive function, memory and attention in patients with depression relative to controls (Cohen's d effect sizes ranging from -0.34 to -0.65). Significant moderate deficits in executive function and attention (Cohen's d ranging from -0.52 to -0.61) and non-significant small/moderate deficits in memory (Cohen's d ranging from -0.22 to -0.54) were found to persist in patients whose depressive symptoms had remitted, indicating that cognitive impairment occurs separately from episodes of low mood in depression.

CONCLUSIONS

Both low mood and cognitive impairment are associated with poor psychosocial functioning. Therefore, we argue that remediation of cognitive impairment and alleviation of depressive symptoms each play an important role in improving outcome for patients with depression. In conclusion, this systematic review and meta-analysis demonstrates that cognitive impairment represents a core feature of depression that cannot be considered an epiphenomenon that is entirely secondary to symptoms of low mood and that may be a valuable target for future interventions.

Learning and memory impairments in a neuroendocrine mouse model of anxiety/depression

Cognitive disturbances are often reported as serious incapacitating symptoms by patients suffering from major depressive disorders (MDDs). Such deficits have been observed in various animal models based on environmental stress. Here, we performed a complete characterization of cognitive functions in a neuroendocrine mouse model of depression based on a chronic (4 weeks) corticosterone administration (CORT). Cognitive performances were assessed using behavioral tests measuring episodic (novel object recognition test, NORT), associative (one-trial contextual fear conditioning, CFC), and visuo-spatial (Morris water maze, MWM; Barnes maze, BM) learning/memory. Altered emotional phenotype after chronic corticosterone treatment was confirmed in mice using tests predictive of anxiety or depression-related behaviors. In the NORT, CORT-treated mice showed a decrease in time exploring the novel object during the test session and a lower discrimination index compared to control mice, characteristic of recognition memory impairment. Associative memory was also impaired, as observed with a decrease in freezing duration in CORT-treated mice in the CFC, thus pointing out the cognitive alterations in this model. In the MWM and in the BM, spatial learning performance but also short-term spatial memory were altered in CORT-treated mice. In the MWM, unlike control animals, CORT-treated animals failed to learn a new location during the reversal phase, suggesting a loss of cognitive flexibility. Finally, in the BM, the lack of preference for the target quadrant during the recall probe trial in animals receiving corticosterone regimen demonstrates that long-term retention was also affected in this paradigm. Taken together, our results highlight that CORT-induced anxio-depressive-like phenotype is associated with a cognitive deficit affecting all aspects of memory tested.

Neurocognitive functioning in bipolar depression: a component structure analysis

BACKGROUND

Previous studies of neurocognitive performance in bipolar disorder (BD) have focused predominantly on euthymia. In this study we aimed to compare the neurocognitive profile of BD patients when depressed with healthy controls and explore the component structure of neurocognitive processes in these populations.

METHOD

Cognitive tests of attention and executive function, immediate memory, verbal and visuospatial learning and memory and psychomotor speed were administered to 53 patients with a SCID-verified diagnosis of BD depression and 47 healthy controls. Test performance was assessed in terms of statistical significance, effect size and percentile standing. Principal component analysis (PCA) was used to explore underlying cognitive factor structure.

RESULTS

Multivariate analysis revealed an overall group effect, depressed BD patients performing significantly worse than controls. Patients performed significantly worse on 18/26 measures examined, with large effect sizes (d > 0.8) on tests of speed of processing, verbal learning and specific executive/working memory processes. Almost all tests produced at least one outcome measure on which ∼25-50% of the BD sample performed at more than 1 standard deviation (s.d.) below the control mean. Between 20% and 34% of patients performed at or below the fifth percentile of the control group in working memory, verbal learning and memory, and psychomotor/processing speed. PCA highlighted overall differences between groups, with fewer extracted components and less specificity in patients.

CONCLUSIONS

Overall, neurocognitive test performance is significantly reduced in BD patients when depressed. The use of different methods of analysing cognitive performance is highlighted, along with the relationship between processes, indicating important directions for future research.

A systematic review of cognitive function in first-episode psychosis, including a discussion on childhood trauma, stress, and inflammation

OBJECTIVE

To carry out a systematic review of the literature addressing cognitive functions in first-episode psychosis (FEP), divided into domains. Although this is not a full "cognitive-genetics-in-schizophrenia review," we will also include putative ideas of mechanism(s) behind these impairments, focusing on how early stress, and genetic vulnerability may moderate cognitive function in psychosis.

METHOD

Relevant studies were identified via computer literature searches for research published up to and including January 2013, only case-control studies were included for the neurocognitive meta-analysis.

RESULTS

Patients with FEP present global cognitive impairment compared to healthy controls. The largest effect size was observed for verbal memory (Cohen's d effect size = 2.10), followed by executive function (effect size = 1.86), and general IQ (effect size = 1.71). However, effect sizes varied between studies.

CONCLUSION

Cognitive impairment across domains, up to severe level based on Cohen's effect size, is present already in FEP studies. However, differences in levels of impairment are observed between studies, as well as within domains, indicating that further consolidation of cognitive impairment over the course of illness may be present. Cognitive abnormalities may be linked to a neurodevelopmental model including increased sensitivity to the negative effect of stress, as well as genetic vulnerability. More research on this field is needed.

Cognitive dysfunction in unipolar depression: implications for treatment

OBJECTIVE

The primary objective of this review is to examine the literature assessing abnormalities in neural circuitry and cognition early in the course of major depressive disorder (MDD) and the impact of these features on treatment selection and long-term outcomes.

DATA SOURCES

English language and peer-reviewed publications were obtained by PubMed/Medline (www.pubmed.org) searches using combinations of major depressive disorder, major depression, or unipolar depression and "first episode", early, cognition, cognitive, executive function and memory. The terms bipolar and psychosis were excluded from the searches. These searches yielded 409 records.

STUDY SELECTION

A total of 12 studies, systematic reviews and meta-analyses were selected that evaluated learning, memory and executive function in individuals with major depressive disorder. Additional publications meeting these criteria were identified from the bibliographies of the 12 selected articles and from the "related citations" section of PubMed.

RESULTS

Difficulty in concentrating and indecisiveness are reported as among the most troubling symptoms by patients with MDD and may limit functional recovery. Cognitive deficits in memory and decision-making are present early in the course of MDD and may be accompanied by structural abnormalities in the hippocampus and prefrontal cortex involved in cognitive functions. Although resolution of cognitive symptoms of depression lags behind recovery from mood symptoms in many patients, preliminary evidence suggests they may improve with antidepressant therapy, but can also persist residually.

CONCLUSIONS

New strategies that target cognitive symptoms of depression in addition to mood symptoms are needed to improve long-term outcomes, particularly functional recovery.

Routine clinical assessment of cognitive functioning in schizophrenia, major depressive disorder, and bipolar disorder

As more evidence points to the association of cognitive dysfunction with mental health disorders, the assessment of cognitive function in routine clinical care of these disorders is increasingly important. Despite this, it remains unknown how cognitive function is measured in routine clinical practice. The objective of this study was to assess psychiatrists' awareness of cognitive dysfunction in mental health disorders and their methods of cognitive assessment. An online survey was disseminated to psychiatrists in Europe, Asia, Australia and the United States. The survey asked about their perceptions of cognitive dysfunction in several mental health disorders, knowledge of cognitive assessment, method of cognitive assessment, and instruments used to measure cognitive function. Among the 61 respondents, most perceived that schizophrenia was associated with the greatest cognitive dysfunction. Many were unaware whether guidelines were available on cognitive assessment. In schizophrenia, 59% of psychiatrists reportedly used cognitive instruments, while the remainder relied solely on patient history interviews. The use of instruments to assess cognition in major depressive disorder (MDD) and bipolar disorder (BPD) was lower, 38% and 37% respectively. Of the reported instruments used, only a few were actually appropriate for use in the diseases of interest (12% in schizophrenia, 3% in MDD and 0% in BPD). Other instruments reported were clinical measures that did not assess cognition. These findings reveal some inconsistencies in psychiatrists' routine clinical evaluation of cognitive function. There appeared to be low use of true cognitive assessment instruments in clinical practice and confusion regarding what constituted a cognitive assessment instrument.

Cognitive remediation as a treatment for major depression: A rationale, review of evidence and recommendations for future research

OBJECTIVE

There is considerable literature regarding the effectiveness of cognitive remediation (CR) in schizophrenia and in conditions such as stroke and traumatic brain injury. Patients with major depressive disorder (MDD) present with significant cognitive impairment which in many cases may not resolve with treatment. Neurobiological data suggest that this may relate to underlying dysfunction of pre-frontal cortical areas of the brain and their connections with limbic structures. There has been limited research into specific CR to activate these areas and target impaired cognitive function in MDD. We therefore review current evidence, examine the theoretical basis for and present a rationale for research into CR in MDD. In addition, we will examine important methodological issues in developing such an approach.

METHOD

Based on preliminary studies using CR-based techniques, data from CR in schizophrenia, data regarding baseline and residual cognitive impairment in depression, and knowledge of the neurobiology of MDD, we examine the possible utility of CR strategies in the treatment of MDD and make recommendations for research in this area.

RESULTS

A small number of previous studies have examined specific CR in MDD. The studies are small and inconclusive. However, data on the neuropsychological function and neurobiology of MDD suggest that this is an approach that deserves further attention and research.

CONCLUSIONS

Further research is required in carefully selected populations, using well-defined CR techniques and some form of comparator treatment.

Association between Neurocognitive Impairment and the Short Allele of the 5-HTT Promoter Polymorphism in Depression: A Pilot Study

Depression has been shown to be associated with cognitive deficits in various cognitive domains. However, it is still unclear which factors contribute to cognitive impairment. The objective of this study was to find out whether a functional polymorphism in the promoter region of the serotonin transporter (5-HTTLPR) gene is associated with the impairment of cognitive functioning among depressed patients. In a pilot study, a sample of 19 patients with major depressive disorder (MDD) and 19 healthy controls was investigated with an extensive psychiatric and neuropsychological examination. All participants were genotyped for 5-HTTLPR. Depressed patients with the short allele of the 5-HTT promoter region exhibited inferior cognitive performance compared to patients with the long allele polymorphism. In healthy controls, no association between genotype and cognitive performance was found. The result suggests that in MDD patients with the short allele of the 5-HTTLPR polymorphism the vulnerability to cognitive impairment is increased compared to MDD patients without the short allele inheritance. These preliminary findings need to be confirmed in a larger cohort of MDD patients.

The Iowa Gambling Task in depression - what have we learned about sub-optimal decision-making strategies?

Our earlier study found patients with depression to show a preference for larger reward as measured by the Iowa Gambling Task (IGT). In this IGT version, larger rewards were associated with even larger consequent losses. In the light of the clinical markers defining depressive disorder, this finding might appear controversial at first. Performance of depressed patients on various decision-making (DM) tasks is typically found to be impaired. Evidence points toward reduced reward learning, as well as the difficulty to shift strategy and integrate environmental changes into DM contingencies. This results in an impaired ability to modulate behavior as a function of reward, or punishment, respectively. Clinical symptoms of the disorder, the genetic profile, as well as personality traits might also influence DM strategies. More severe depression increased sensitivity to immediate large punishment, thus predicting future decisions, and was also associated with higher harm avoidance. Anhedonic features diminished reward learning abilities to a greater extent, even predicting clinical outcome. Several questions about how these aspects relate remain to be clarified. Is there a genetic predisposition for the DM impairment preceding mood symptoms? Is it the consequence of clinical signs or even learned behavior serving as a coping strategy? Are patients prone to develop an aversion of loss or are they unable to sense or deal with reward or the preference of reward? Does the DM deficit normalize or is a persisting impairment predictor for clinical outcome or relapse risk? To what extent is it influenced by medication effects? How does a long-lasting DM deficit affect daily life and social interactions? Strikingly, research evidence indicates that depressed patients tend to behave less deceptive and more self-focused, resulting in impaired social DM. The difficulty in daily interpersonal interactions might contribute to social isolation, further intensifying depressive symptoms.

Verbal memory functioning in recurrent depression during partial remission and remission-Brief report

The aim of the present study was to investigate verbal memory performance in a group of patients with remitted and partial remitted major depressive disorder. Thirty-one patients and 31 healthy matched controls were included in the study. Results from the California Verbal Learning Test show intact verbal memory performance in the patient group regarding learning, recall and recognition. However, patients had significantly poorer performance compared to healthy controls in immediate recall of the first trial in the verbal memory test. In conclusion, the patient group showed intact memory performance, when material is presented more than once. These findings indicate that memory performance in MDD patients with partial remission and remission benefit from repetition of material.

The touchscreen operant platform for testing learning and memory in rats and mice

An increasingly popular method of assessing cognitive functions in rodents is the automated touchscreen platform, on which a number of different cognitive tests can be run in a manner very similar to touchscreen methods currently used to test human subjects. This methodology is low stress (using appetitive rather than aversive reinforcement), has high translational potential and lends itself to a high degree of standardization and throughput. Applications include the study of cognition in rodent models of psychiatric and neurodegenerative diseases (e.g., Alzheimer's disease, schizophrenia, Huntington's disease, frontotemporal dementia), as well as the characterization of the role of select brain regions, neurotransmitter systems and genes in rodents. This protocol describes how to perform four touchscreen assays of learning and memory: visual discrimination, object-location paired-associates learning, visuomotor conditional learning and autoshaping. It is accompanied by two further protocols (also published in this issue) that use the touchscreen platform to assess executive function, working memory and pattern separation.