Structural and functional models of depression: from sub-types to substrates

Auditory event-related potentials in separating patients with depressive disorders and non-depressed controls: A narrative review

This narrative review brings together the findings regarding the differences in the auditory event-related potentials (ERPs) between patients with depressive disorder and non-depressed control subjects. These studies' results can inform us of the possible alterations in sensory-cognitive processing in depressive disorders and the potential of using these ERPs in clinical applications. Auditory P3, mismatch negativity (MMN) and loudness dependence of auditory evoked potentials (LDAEP) were the subjects of the investigation. A search in PubMed yielded 84 studies. The findings of the reviewed studies were not highly consistent, but some patterns could be identified. For auditory P3b, the common findings were attenuated amplitude and prolonged latency among depressed patients. Regarding auditory MMN, especially the amplitude of duration deviance MMN was commonly attenuated, and the amplitude of frequency deviance MMN was increased in depressed patients. In LDAEP studies, generally, no differences between depressed patients and non-depressed controls were reported, although some group differences concerning specific depression subtypes were found. This review posits that future research should investigate whether certain stimulus conditions are particularly efficient at separating depressed and non-depressed participant groups. Future studies should contrast responses in different subpopulations of depressed patients, as well as different clinical groups (e.g., depressive disorder and anxiety disorder patients), to investigate the specificity of the auditory ERP alterations for depressive disorders.

The 2020 Royal Australian and New Zealand College of Psychiatrists clinical practice guidelines for mood disorders

OBJECTIVES

To provide advice and guidance regarding the management of mood disorders, derived from scientific evidence and supplemented by expert clinical consensus to formulate s that maximise clinical utility.

METHODS

Articles and information sourced from search engines including PubMed, EMBASE, MEDLINE, PsycINFO and Google Scholar were supplemented by literature known to the mood disorders committee (e.g. books, book chapters and government reports) and from published depression and bipolar disorder guidelines. Relevant information was appraised and discussed in detail by members of the mood disorders committee, with a view to formulating and developing consensus-based recommendations and clinical guidance. The guidelines were subjected to rigorous consultation and external review involving: expert and clinical advisors, key stakeholders, professional bodies and specialist groups with interest in mood disorders.

RESULTS

The Royal Australian and New Zealand College of Psychiatrists mood disorders clinical practice guidelines 2020 (MDcpg²⁰²⁰) provide up-to-date guidance regarding the management of mood disorders that is informed by evidence and clinical experience. The guideline is intended for clinical use by psychiatrists, psychologists, primary care physicians and others with an interest in mental health care.

CONCLUSION

The MDcpg²⁰²⁰ builds on the previous 2015 guidelines and maintains its joint focus on both depressive and bipolar disorders. It provides up-to-date recommendations and guidance within an evidence-based framework, supplemented by expert clinical consensus.

MOOD DISORDERS COMMITTEE

Gin S Malhi (Chair), Erica Bell, Darryl Bassett, Philip Boyce, Richard Bryant, Philip Hazell, Malcolm Hopwood, Bill Lyndon, Roger Mulder, Richard Porter, Ajeet B Singh and Greg Murray.

Peripheral Markers of Depression

Major Depressive Disorder (MDD) is a leading cause of disability worldwide, creating a high medical and socioeconomic burden. There is a growing interest in the biological underpinnings of depression, which are reflected by altered levels of biological markers. Among others, enhanced inflammation has been reported in MDD, as reflected by increased concentrations of inflammatory markers-C-reactive protein, interleukin-6, tumor necrosis factor-α and soluble interleukin-2 receptor. Oxidative and nitrosative stress also plays a role in the pathophysiology of MDD. Notably, increased levels of lipid peroxidation markers are characteristic of MDD. Dysregulation of the stress axis, along with increased cortisol levels, have also been reported in MDD. Alterations in growth factors, with a significant decrease in brain-derived neurotrophic factor and an increase in fibroblast growth factor-2 and insulin-like growth factor-1 concentrations have also been found in MDD. Finally, kynurenine metabolites, increased glutamate and decreased total cholesterol also hold promise as reliable biomarkers for MDD. Research in the field of MDD biomarkers is hindered by insufficient understanding of MDD etiopathogenesis, substantial heterogeneity of the disorder, common co-morbidities and low specificity of biomarkers. The construction of biomarker panels and their evaluation with use of new technologies may have the potential to overcome the above mentioned obstacles.

Carving depression at its joints? Psychometric properties of the Sydney Melancholia Prototype Index

Parker and colleagues developed the Sydney Melancholia Prototype Index (SMPI), a 24-item measure to assess a potential subtype of depression: melancholia. While research supports the validity of the measure, no study has assessed its psychometric properties. We recruited 1633 participants online, of whom 487 reported a lifetime period of depressed mood or anhedonia and were administered the SMPI. We conducted confirmatory factor analyses (CFA) of the SMPI, to assess the proposed fit of the measure. We also conducted exploratory factor analyses (EFA) to explore the structure implied by the current data. CFA did not support the hypothesized factor structure of the SMPI, no matter what structure we assumed as primary (i.e., a one factor, two factor, or bifactor model). An EFA suggested a five-factor solution wherein several items did not appear to co-vary reliably and other factors captured the severity of melancholic symptoms, negative mood reactivity, positive mood reactivity, emotionality and family relationships, and early life adversity. The SMPI may not measure a single construct. Future research should explore the longitudinal association between depression severity, contaminant symptoms, positive and negative mood reactivity, and early life experiences.

Trauma and depressive symptomatology in middle-aged persons at high risk of dementia: the PREVENT Dementia Study

OBJECTIVE

Depression and trauma are associated with changes in brain regions implicated in Alzheimer's disease. The present study examined associations between childhood trauma, depression, adult cognitive functioning and risk of dementia.

METHODS

Data from 378 participants in the PREVENT Dementia Study aged 40-59 years. Linear and logistic models were used to assess associations between childhood trauma, depression, dementia risk, cognitive test scores and hippocampal volume.

RESULTS

Childhood trauma was associated with depression and reduced hippocampal volume but not current cognitive function or dementia risk. Poorer performance on a delayed face/name recall task was associated with depression. Childhood trauma was associated with lower hippocampal volume however poorer cognitive performance was mediated by depression rather than structural brain differences.

CONCLUSION

Depressive symptomatology may be associated with dementia risk via multiple pathways, and future studies should consider subtypes of depressive symptomatology when examining its relationship to dementia.

Psychotic depression in hospitalized patients: Longitudinal outcomes of psychotic vs. nonpsychotic depression among inpatients

Even though psychotic depression is related to worse outcomes than nonpsychotic depression, there is increasing evidence that this greater severity is not solely explained by the depressive symptoms. We evaluated the socio-demographic and clinical characteristics, as well as the differences in clinical outcomes of psychiatric hospitalization between psychotic and non-psychotic depression. Two-hundred-eighty-eight depressive inpatients were assessed within 72 h after hospitalization and 24 h before discharge. We compared scores of Hamilton Depression Rating Scale 17-items (HDRS-17), Clinical Global Impression (CGI), Brief Psychiatric Rating Scale (BPRS), and Global Assessment of Functioning (GAF) between psychotic and nonpsychotic patients. Instruments were compared both cross-sectionally - on admission and discharge - and longitudinally. Longitudinal outcomes were corrected for potential confounders (sex, age, age at disease onset, years of study, previous history of mania/hypomania, electroconvulsive therapy in current hospitalization, history of attempted suicide, number of suicide attempts, and previous hospitalizations). One-hundred-thirty-one depressive inpatients (45.4%) presented psychotic features. Both groups showed similar HDRS-17 scores at admission and discharge. However, psychotic patients had worse scores on BPRS, CGI, and GAF at both timepoints. Both groups had similar improvement on HDRS-17 (P = 0.75), CGI (P = 0.5), and GAF (P = 0.84), but psychotic patients had greater improvement on BPRS (P < 0.001). Psychotic inpatients showed worse clinical and functional parameters. Nonetheless, the groups did not differ in depressive symptom severity. These findings reinforce the hypothesis that depressive episode with psychotic features is a more severe form of the disease irrespective of intensity of affective symptomatology.

Computational modeling of the monoaminergic neurotransmitter and male neuroendocrine systems in an analysis of therapeutic neuroadaptation to chronic antidepressant

Second-line depression treatment involves augmentation with one (rarely two) additional drugs, of chronic administration of a selective serotonin reuptake inhibitor (SSRI), which is the first-line depression treatment. Unfortunately, many depressed patients still fail to respond even after months to years of searching to find an effective combination. To aid in the identification of potentially effective antidepressant combinations, we created a computational model of the monoaminergic neurotransmitter (serotonin, norepinephrine, and dopamine), stress-hormone (cortisol), and male sex hormone (testosterone) systems. The model was trained via machine learning to represent a broad range of empirical observations. Neuroadaptation to chronic drug administration was simulated through incremental adjustments in model parameters that corresponded to key regulatory components of the neurotransmitter and neurohormone systems. Analysis revealed that neuroadaptation in the model depended on all of the regulatory components in complicated ways, and did not reveal any one or a few specific components that could be targeted in the design of antidepressant treatments. We used large sets of neuroadapted states of the model to screen 74 different drug and hormone combinations and identified several combinations that could potentially be therapeutic for a higher proportion of male patients than SSRIs by themselves.

Computational Analysis of Therapeutic Neuroadaptation to Chronic Antidepressant in a Model of the Monoaminergic Neurotransmitter and Stress Hormone Systems

The clinical practice of selective serotonin reuptake inhibitor (SSRI) augmentation relies heavily on trial-and-error. Unfortunately, the drug combinations prescribed today fail to provide relief for many depressed patients. In order to identify potentially more effective treatments, we developed a computational model of the monoaminergic neurotransmitter and stress-steroid systems that neuroadapts to chronic administration of combinations of antidepressant drugs and hormones by adjusting the strengths of its transmitter-system components (TSCs). We used the model to screen 60 chronically administered drug/hormone pairs and triples, and identified as potentially therapeutic those combinations that raised the monoamines (serotonin, norepinephrine, and dopamine) but lowered cortisol following neuroadaptation in the model. We also evaluated the contributions of individual and pairs of TSCs to therapeutic neuroadaptation with chronic SSRI using sensitivity, correlation, and linear temporal-logic analyses. All three approaches revealed that therapeutic neuroadaptation to chronic SSRI is an overdetermined process that depends on multiple TSCs, providing a potential explanation for the clinical finding that no single antidepressant regimen alleviates depressive symptoms in all patients.

[Genetic comorbidity of depression and somatic disorders]

The aim of our review was to evaluate the perspectives of new therapeutic approaches in comorbid depressive and somatic disorders based on common pathological mechanisms and their genetic risk factors. Literature analysis showed that depression was a complex heterogeneous condition associated with significant prevalence of metabolic, cardiovascular and immune disturbances. The understanding of common molecular mechanisms of risks and course of abovementioned disorders could provide a new strategy for early diagnosis and therapeutic optimization and give the opportunity of 'targeted' approach to different pathological elements.

Lower levels of brain-derived neurotrophic factor are associated with melancholic psychomotor retardation among depressed inpatients

OBJECTIVES

Melancholic depression is a type of depression which is closely related to biological variables than are other types of depression. Its clinical features can be assessed using six items on the Hamilton Depression Rating Scale (HAM-D₆ ). Previous studies have shown, using item response theory, that the symptom depressed mood is the least severe melancholic feature; work and activities, somatic symptoms and psychic anxiety are of moderate severity; and feelings of guilt and psychomotor retardation are the most severe. We aimed to evaluate whether the more severe melancholic signs or symptoms were associated with decreases in brain-derived neurotrophic factor (BDNF) levels.

METHODS

A total of 151 severely depressed inpatients had their BDNF levels analyzed by comparing those who presented with each HAM-D₆ melancholic feature to those for whom the HAM-D₆ feature was absent, using multiple linear regressions. The levels of BDNF of patients who presented with each melancholic feature were also compared with those of 100 healthy controls.

RESULTS

Depressed patients' median BDNF level was 44.06 ng/mL (interquartile range [IQR]: 33.99-62.4 ng/mL), and controls' median BDNF level was 65.22 ng/mL (IQR: 49.87-76.08 ng/mL) (P < .001). The presence of depressed mood, work and activities, somatic symptoms, psychic anxiety, and guilty feelings was not associated with BDNF levels. However, the presence of psychomotor retardation was associated with reduced BDNF (median reduction -10.07 ng/mL; 95% confidence interval [CI]: -19.43 to -0.71; P = .03).

CONCLUSIONS

To the best of our knowledge, this study is the first to associate BDNF levels with melancholic features in a sample of severely depressed inpatients. The main finding of this study was that severely depressed inpatients who presented the most severe melancholic feature, psychomotor retardation, had significantly reduced BDNF levels in the blood.

Distinguishing Subgroups Based on Psychomotor Functioning among Patients with Major Depressive Disorder

BACKGROUND

Retardation and agitation are symptoms of major depressive disorder (MDD), and their presence could play a role in determining clinically meaningful depressive subtypes such as nonmelancholic depression (NMD) and melancholic depression (MD). In this project, we explored whether three depression subgroups (NMD, MD with psychotic symptoms, and MD without psychotic symptoms) could be distinguished based on objective measures of psychomotor functioning.

METHODS

Sixty-nine patients with MDD underwent extensive clinical and psychomotor testing prior to treatment with electroconvulsive therapy. Psychomotor functioning was assessed subjectively using the Core Assessment of Psychomotor Change (CORE) and objectively by means of both 24-h actigraphy and performance on a fine motor drawing task.

RESULTS

The daytime activity levels measured by actigraphy were significantly lower (F = 7.1, p = 0.0004) in MD patients both with and without psychotic symptoms than in those with NMD. No objective psychomotor variable was able to distinguish between melancholic patients with and those without psychotic symptoms.

CONCLUSIONS

The depression subtypes NMD, MD with psychotic symptoms, and MD without psychotic symptoms are not marked by increasing psychomotor retardation, possibly because psychomotor disturbance in MD with psychotic symptoms often consists of agitation rather than retardation, or a mixture of the two. However, psychomotor functioning as measured by actigraphy can be used to distinguish between NMD patients and MD patients.

Computational Model of Antidepressant Response Heterogeneity as Multi-pathway Neuroadaptation

Current hypotheses cannot fully explain the clinically observed heterogeneity in antidepressant response. The therapeutic latency of antidepressants suggests that therapeutic outcomes are achieved not by the acute effects of the drugs, but rather by the homeostatic changes that occur as the brain adapts to their chronic administration. We present a computational model that represents the known interactions between the monoaminergic neurotransmitter-producing brain regions and associated non-monoaminergic neurotransmitter systems, and use the model to explore the possible ways in which the brain can homeostatically adjust to chronic antidepressant administration. The model also represents the neuron-specific neurotransmitter receptors that are known to adjust their strengths (expressions or sensitivities) in response to chronic antidepressant administration, and neuroadaptation in the model occurs through sequential adjustments in these receptor strengths. The main result is that the model can reach similar levels of adaptation to chronic administration of the same antidepressant drug or combination along many different pathways, arriving correspondingly at many different receptor strength configurations, but not all of those adapted configurations are also associated with therapeutic elevations in monoamine levels. When expressed as the percentage of adapted configurations that are also associated with elevations in one or more of the monoamines, our modeling results largely agree with the percentage efficacy rates of antidepressants and antidepressant combinations observed in clinical trials. Our neuroadaptation model provides an explanation for the clinical reports of heterogeneous outcomes among patients chronically administered the same antidepressant drug regimen.

The Evolutionary Theory of Depression

The evolutionary success of Homo sapiens is attributed to the following two factors: the upright body posture (which freed our hands and allowed unconstrained operation of various objects) and intensive development of the frontal lobes, mainly the Broca area of the brain. Underlining the uniqueness of the human brain, we often forget about the fact that the frontal lobes – the most developed part of the brain – are at the same time our greatest weakness, exposed to the action of damaging factors in our evolving environment. Is depression the cost of evolution?

Distinct resting-state perfusion patterns underlie psychomotor retardation in unipolar vs. bipolar depression

OBJECTIVE

Psychomotor abnormalities characterize both unipolar (UP) depression and bipolar (BP) depression. We aimed to assess their neurobiological correlates in terms of motor activity (AL) and resting-state cerebral blood flow (rCBF) and investigate their association in BP, UP, and healthy controls (HC).

METHOD

We enrolled 42 depressed patients (22 BP, 20 UP) and 19 HC matched for age, gender, education, income. AL and rCBF were objectively assessed with the use of wrist actigraphy and arterial spin labeling. Group differences and the association of AL and rCBF were computed.

RESULTS

Activity level was significantly reduced in patients, but no difference was found between BP and UP. Increased perfusion was found in BP compared with UP and HC, in multiple brain areas. We found positive correlations of rCBF and AL in BP and UP, in different parts of the insula and frontal regions. Only BP showed a cluster in the left precentral gyrus. In HC, only inverse correlations of AL and rCBF were found.

CONCLUSION

The differences in rCBF and in the localization of the clusters of positive AL/rCBF correlations between BP and UP suggest that different neural impairments may underlie motor symptoms in the two disorders, but finally converge in phenotypically similar manifestations.

Cognitive-behavioural therapy versus psychodynamic psychotherapy for the treatment of depression: a critical review of evidence and current issues

Two of the most popular psychotherapeutic approaches to treat depression are cognitive-behavioural therapy and psychodynamic psychotherapy, yet little consensus has been reached concerning which therapy is most beneficial for the treatment of depression. A review of the literature revealed that, while cognitive-behavioural therapy and psychodynamic psychotherapy are the most effective psychotherapeutic modalities for the treatment of depression, evidence suggests that neither of these modalities is superior to the other. Furthermore, multiple issues plague the studies investigating these treatments. Efficacy and effectiveness are often confounded, while rates of remission and response are often far less than might be expected from such highly regarded and widely used treatments. Severity of depression appears to moderate treatment outcomes, yet many studies overlook this, while the impact that the aetiology of a patient’s depression has on treatment outcomes is largely ignored in the literature. Additionally, a majority of studies have focused on therapies of short duration, which often have poor follow-up results. Finally, mechanisms of change in the treatment of depression have been ignored to a large extent, but there is some evidence that non-specific therapeutic factors may be more important than specific therapeutic techniques in producing positive treatment outcomes. These issues need to be closely examined and resolved if researchers and clinicians are serious about optimising treatments, improving outcomes, and adequately addressing the serious problem of depression.

Vulnerability for new episodes in recurrent major depressive disorder: protocol for the longitudinal DELTA-neuroimaging cohort study

INTRODUCTION

Major depressive disorder (MDD) is widely prevalent and severely disabling, mainly due to its recurrent nature. A better understanding of the mechanisms underlying MDD-recurrence may help to identify high-risk patients and to improve the preventive treatment they need. MDD-recurrence has been considered from various levels of perspective including symptomatology, affective neuropsychology, brain circuitry and endocrinology/metabolism. However, MDD-recurrence understanding is limited, because these perspectives have been studied mainly in isolation, cross-sectionally in depressed patients. Therefore, we aim at improving MDD-recurrence understanding by studying these four selected perspectives in combination and prospectively during remission.

METHODS AND ANALYSIS

In a cohort design, we will include 60 remitted, unipolar, unmedicated, recurrent MDD-participants (35-65 years) with ≥ 2 MDD-episodes. At baseline, we will compare the MDD-participants with 40 matched controls. Subsequently, we will follow-up the MDD-participants for 2.5 years while monitoring recurrences. We will invite participants with a recurrence to repeat baseline measurements, together with matched remitted MDD-participants. Measurements include questionnaires, sad mood-induction, lifestyle/diet, 3 T structural (T1-weighted and diffusion tensor imaging) and blood-oxygen-level-dependent functional MRI (fMRI) and MR-spectroscopy. fMRI focusses on resting state, reward/aversive-related learning and emotion regulation. With affective neuropsychological tasks we will test emotional processing. Moreover, we will assess endocrinology (salivary hypothalamic-pituitary-adrenal-axis cortisol and dehydroepiandrosterone-sulfate) and metabolism (metabolomics including polyunsaturated fatty acids), and store blood for, for example, inflammation analyses, genomics and proteomics. Finally, we will perform repeated momentary daily assessments using experience sampling methods at baseline. We will integrate measures to test: (1) differences between MDD-participants and controls; (2) associations of baseline measures with retro/prospective recurrence-rates; and (3) repeated measures changes during follow-up recurrence. This data set will allow us to study different predictors of recurrence in combination.

ETHICS AND DISSEMINATION

The local ethics committee approved this study (AMC-METC-Nr.:11/050). We will submit results for publication in peer-reviewed journals and presentation at (inter)national scientific meetings.

TRIAL REGISTRATION NUMBER

NTR3768.

Royal Australian and New Zealand College of Psychiatrists clinical practice guidelines for mood disorders

OBJECTIVES

To provide guidance for the management of mood disorders, based on scientific evidence supplemented by expert clinical consensus and formulate recommendations to maximise clinical salience and utility.

METHODS

Articles and information sourced from search engines including PubMed and EMBASE, MEDLINE, PsycINFO and Google Scholar were supplemented by literature known to the mood disorders committee (MDC) (e.g., books, book chapters and government reports) and from published depression and bipolar disorder guidelines. Information was reviewed and discussed by members of the MDC and findings were then formulated into consensus-based recommendations and clinical guidance. The guidelines were subjected to rigorous successive consultation and external review involving: expert and clinical advisors, the public, key stakeholders, professional bodies and specialist groups with interest in mood disorders.

RESULTS

The Royal Australian and New Zealand College of Psychiatrists clinical practice guidelines for mood disorders (Mood Disorders CPG) provide up-to-date guidance and advice regarding the management of mood disorders that is informed by evidence and clinical experience. The Mood Disorders CPG is intended for clinical use by psychiatrists, psychologists, physicians and others with an interest in mental health care.

CONCLUSIONS

The Mood Disorder CPG is the first Clinical Practice Guideline to address both depressive and bipolar disorders. It provides up-to-date recommendations and guidance within an evidence-based framework, supplemented by expert clinical consensus.

MOOD DISORDERS COMMITTEE

Professor Gin Malhi (Chair), Professor Darryl Bassett, Professor Philip Boyce, Professor Richard Bryant, Professor Paul Fitzgerald, Dr Kristina Fritz, Professor Malcolm Hopwood, Dr Bill Lyndon, Professor Roger Mulder, Professor Greg Murray, Professor Richard Porter and Associate Professor Ajeet Singh.

INTERNATIONAL EXPERT ADVISORS

Professor Carlo Altamura, Dr Francesco Colom, Professor Mark George, Professor Guy Goodwin, Professor Roger McIntyre, Dr Roger Ng, Professor John O'Brien, Professor Harold Sackeim, Professor Jan Scott, Dr Nobuhiro Sugiyama, Professor Eduard Vieta, Professor Lakshmi Yatham.

AUSTRALIAN AND NEW ZEALAND EXPERT ADVISORS

Professor Marie-Paule Austin, Professor Michael Berk, Dr Yulisha Byrow, Professor Helen Christensen, Dr Nick De Felice, A/Professor Seetal Dodd, A/Professor Megan Galbally, Dr Josh Geffen, Professor Philip Hazell, A/Professor David Horgan, A/Professor Felice Jacka, Professor Gordon Johnson, Professor Anthony Jorm, Dr Jon-Paul Khoo, Professor Jayashri Kulkarni, Dr Cameron Lacey, Dr Noeline Latt, Professor Florence Levy, A/Professor Andrew Lewis, Professor Colleen Loo, Dr Thomas Mayze, Dr Linton Meagher, Professor Philip Mitchell, Professor Daniel O'Connor, Dr Nick O'Connor, Dr Tim Outhred, Dr Mark Rowe, Dr Narelle Shadbolt, Dr Martien Snellen, Professor John Tiller, Dr Bill Watkins, Dr Raymond Wu.

Heterogeneity in the prognosis of major depression: from the common cold to a highly debilitating and recurrent illness

Two different and seemingly competing views on the diagnosis of major depressive disorder (MDD) exist. The first is that the diagnosis conflates adaptive sadness reactions with pathological states of depressed mood and that MDD is overdiagnosed and overtreated. The second is that MDD is an underdiagnosed and undertreated disorder, and one that is best characterised by a severe, chronic, recurrent or treatment-resistant course. Existing research suggests that both views are valid and merit being integrated. Anywhere from 30 to 50% of individuals will meet criteria for MDD at some point in their life. About half of these episodes are of brief duration and unlikely to recur. However, a remaining half is either chronic or recurrent. Data on the outpatient diagnosis of depression support the view that depression is simultaneously underdiagnosed and undertreated as well as overdiagnosed and overtreated. About one-third of the patients who meet criteria for MDD and receive placebos experience clinically significant and long-lasting improvement. Many other patients, however, are unresponsive to one or multiple active treatments. Thus, the diagnosis of MDD likely applies to individuals who are experiencing either normal periods of sadness or single-episode afflictions that are mild, unlikely to recur, and are placebo responsive, as well as to individuals with more severe clinical profiles. More research is needed that can help ascertain what contextual or biopsychological variables help distinguish between individuals who may be experiencing adaptive states of negative affect and those who experience severe, chronic, recurrent or treatment-resistant depressions.

Mood disorders: neurocognitive models

OBJECTIVES

In recent years, a number of neurocognitive models stemming from psychiatry and psychology schools of thought have conceptualized the pathophysiology of mood disorders in terms of dysfunctional neural mechanisms that underpin and drive neurocognitive processes. Though these models have been useful for advancing our theoretical understanding and facilitating important lines of research, translation of these models and their application within the clinical arena have been limited-partly because of lack of integration and synthesis. Cognitive neuroscience provides a novel perspective for understanding and modeling mood disorders. This selective review of influential neurocognitive models develops an integrative approach that can serve as a template for future research and the development of a clinically meaningful framework for investigating, diagnosing, and treating mood disorders.

METHODS

A selective literature search was conducted using PubMed and PsychINFO to identify prominent neurobiological and neurocognitive models of mood disorders.

RESULTS

Most models identify similar neural networks and brain regions and neuropsychological processes in the neurocognition of mood, however, they differ in terms of specific functions attached to neural processes and how these interact. Furthermore, cognitive biases, reward processing and motivation, rumination, and mood stability, which play significant roles in the manner in which attention, appraisal, and response processes are deployed in mood disorders, are not sufficiently integrated. The inclusion of interactions between these additional components enhances our understanding of the etiology and pathophysiology of mood disorders.

CONCLUSIONS

Through integration of key cognitive functions and understanding of how these interface with neural functioning within neurocognitive models of mood disorders, a framework for research can be created for translation to diagnosis and treatment of mood disorders.

Fruit and vegetable consumption and the risk of depression: A meta-analysis

OBJECTIVE

Epidemiologic investigations evaluating the association of fruit and vegetable consumption with depression risk have yielded controversial results. Therefore, a meta-analysis was carried out to qualitatively summarize the evidence regarding association of fruit and vegetable intake with risk of depression in the general population.

METHODS

PubMed, Embase, and Web of Knowledge were searched for relevant articles published up to June 2015. To evaluate the association of fruit and vegetable intake with depression risk, combined relative risks were calculated with the fixed or random effects model. Meta-regression was conducted to explore potential sources of heterogeneity. Publication bias was estimated by the Egger's test and the funnel plot.

RESULTS

Ten studies involving 227 852 participants for fruit intake and eight studies involving 218 699 participants for vegetable intake were finally included in this study. The combined relative risk (95% confidence interval) of depression for the highest versus lowest category of fruit and vegetable intake was 0.86 (0.81, 0.91; P < 0.01) and 0.89 (0.83, 0.94; P < 0.01), respectively. In subgroup analyses stratified by study design, the inverse association of fruit (0.83 [0.77, 0.91; P = 0.006]) and vegetable (0.88 [0.79, 0.96; P = 0.007]) intake with risk of depression was also observed in the cohort study.

CONCLUSIONS

This meta-analysis indicated that fruit and vegetable consumption might be inversely associated with the risk of depression, respectively.

[Spectral model of therapy resistant depression]

In the present article, we describe different staging models of therapy resistant depression (TRD). Their advantages and disadvantages are pointed out. Also the possibilities of using various TRD staging models in clinical practice are considered. It is proposed to develop a single spectral model of TRD.

Association between core-assigned melancholia and the melancholia subscale of the HAM-D

BACKGROUND

Clinical observation and research data suggest that major depression (MD) is a heterogeneous disorder, possibly representing a group of different clinical entities. The identification of more homogeneous subtypes of depression could enhance research and enable development of more specific treatments. A melancholic subtype of MD, defined by the presence of observable psychomotor disturbance (PMD), is proposed to be more homogeneous and associated with biological determinants. The aim of this study was to investigate the homogeneity of this melancholic subtype in terms of symptoms by searching for an association between melancholia and a unidimensional subscale of the Hamilton Depression Rating Scale (HAM-D) proposed to have biological validity (HAM-D6).

METHODS

A cross-sectional assessment of 385 outpatients presenting with a unipolar major depressive episode was carried out to evaluate depressive symptoms using the HAM-D and melancholic or nonmelancholic subtype, according to the CORE measure of PMD.

RESULTS

Melancholic patients exhibited more severe depressive symptoms, mainly associated with the HAM-D6. The items of this melancholia subscale represent 42.3% of the total HAM-D and were responsible for 59.4% of between-group differences. Correlation analysis showed similar results.

LIMITATIONS

Most patients received previous treatment, and some were not at the nadir of the episode when assessed. This could have lowered the CORE measure sensibility.

CONCLUSION

Melancholic depression, as assigned by the CORE measure, represents a more severe and homogeneous subtype of MD. This observation may allow identification of proper biomarkers and development of more specific treatments.

Melancholic-Like behaviors and circadian neurobiological abnormalities in melatonin MT1 receptor knockout mice

BACKGROUND

Melancholic depression, described also as endogenous depression, is a mood disorder with distinctive specific psychopathological features and biological homogeneity, including anhedonia, circadian variation of mood, psychomotor activation, weight loss, diurnal cortisol changes, and sleep disturbances. Although several hypotheses have been proposed, the etiology of this disorder is still unknown.

METHODS

Behavioral, electrophysiological and biochemical approaches were used to characterize the emotional phenotype, serotonergic and noradrenergic electrical activity, and corticosterone in melatonin MT1 receptor knockout mice and their wild type counterparts, during both light and dark phases.

RESULTS

Melatonin MT1 receptor knockout mice have decreased mobility in the forced swim and tail suspension tests as well as decreased sucrose consumption, mostly during the dark/inactive phase. These mood variations are reversed by chronic treatment with the tricyclic antidepressant desipramine. In addition, MT1 receptor knockout mice exhibit psychomotor disturbances, higher serum levels of corticosterone the dark phase, and a blunted circadian variation of corticosterone levels. In vivo electrophysiological recordings show a decreased burst-firing activity of locus coeruleus norepinephrine neurons during the dark phase. The circadian physiological variation in the spontaneous firing activity of high-firing neuronal subpopulations of both norepinephrine neurons and dorsal raphe serotonin neurons are abolished in MT1 knockout mice.

CONCLUSIONS

These data demonstrate that melatonin MT1 receptor knockout mice recapitulate several behavioral and neurobiological circadian changes of human melancholic depression and, for the first time, suggest that the MT1 receptor may be implicated in the pathogenesis of melancholic depression and is a potential pharmacological target for this mental condition.

The functional anatomy of psychomotor disturbances in major depressive disorder

Psychomotor disturbances (PMD) are a classic feature of depressive disorder that provides rich clinical information. The aim our narrative review was to characterize the functional anatomy of PMD by summarizing findings from neuroimaging studies. We found evidence across several neuroimaging modalities that suggest involvement of fronto-striatal neurocircuitry, and monoaminergic pathways and metabolism. We suggest that PMD in major depressive disorder emerge from an alteration of limbic signals, which influence emotion, volition, higher-order cognitive functions, and movement.

Major depressive disorder with melancholia displays robust alterations in resting state heart rate and its variability: implications for future morbidity and mortality

Background: Major depressive disorder (MDD) is associated with increased heart rate and reductions in its variability (heart rate variability, HRV) – markers of future morbidity and mortality – yet prior studies have reported contradictory effects. We hypothesized that increases in heart rate and reductions in HRV would be more robust in melancholia relative to controls, than in patients with non-melancholia.

Methods: A total of 72 patients with a primary diagnosis of MDD (age M: 36.26, SE: 1.34; 42 females) and 94 controls (age M: 35.69, SE: 1.16; 52 females) were included in this study. Heart rate and measures of its variability (HRV) were calculated from two 2-min electrocardiogram recordings during resting state. Propensity score matching controlled imbalance on potential confounds between patients with melancholia (n = 40) and non-melancholia (n = 32) including age, gender, disorder severity, and comorbid anxiety disorders.

Results: MDD patients with melancholia displayed significantly increased heart rate and lower resting-state HRV (including the square root of the mean squared differences between successive N–N intervals, the absolute power of high frequency and standard deviation of the Poincaré plot perpendicular to the line of identity measures of HRV) relative to controls, findings associated with a moderate effect size (Cohens d’s = 0.56–0.58). Patients with melancholia also displayed an increased heart rate relative to those with non-melancholia (Cohen’s d = 0.20).

Conclusion: MDD patients with melancholia – but not non-melancholia – display robust increases in heart rate and decreases in HRV. These findings may underpin a variety of behavioral impairments in patients with melancholia including somatic symptoms, cognitive impairment, reduced responsiveness to the environment, and over the longer-term, morbidity and mortality.

Visual perception during mirror-gazing at one's own face in patients with depression

In normal observers, gazing at one's own face in the mirror for a few minutes, at a low illumination level, produces the apparition of strange faces. Observers see distortions of their own faces, but they often see hallucinations like monsters, archetypical faces, faces of relatives and deceased, and animals. In this research, patients with depression were compared to healthy controls with respect to strange-face apparitions. The experiment was a 7-minute mirror-gazing test (MGT) under low illumination. When the MGT ended, the experimenter assessed patients and controls with a specifically designed questionnaire and interviewed them, asking them to describe strange-face apparitions. Apparitions of strange faces in the mirror were very reduced in depression patients compared to healthy controls. Depression patients compared to healthy controls showed shorter duration of apparitions; minor number of strange faces; lower self-evaluation rating of apparition strength; lower self-evaluation rating of provoked emotion. These decreases in depression may be produced by deficits of facial expression and facial recognition of emotions, which are involved in the relationship between the patient (or the patient's ego) and his face image (or the patient's bodily self) that is reflected in the mirror.

Unlocking the diagnosis of depression in primary care: Which key symptoms are GPs using to determine diagnosis and severity?

OBJECTIVE

Diagnosing depression in primary care settings is challenging. Patients are more likely to present with somatic symptoms, and typically with mild depression. Use of assessment scales is variable. In this context, it is uncertain how general practitioners (GPs) determine the severity of depressive illness in clinical practice. The aim of the current paper was to identify which symptoms are used by GPs when diagnosing depression and when determining severity.

METHOD

A total of 1760 GPs participated in the RADAR Program, an educational program focusing on the diagnosis and management of clinical depression. GPs identified a maximum of four patients whom they diagnosed with depression and answered questions regarding their diagnostic decision-making process for each patient.

RESULTS

Overall, assessment of depression severity was influenced more by somatic symptoms collectively than emotional symptoms. Suicidal thoughts, risk of self-harm, lack of enjoyment and difficulty with activities were amongst the strongest predictors of a diagnosis of severe depression.

CONCLUSIONS

The conclusions are threefold: (1) collectively, somatic symptoms are the most important predictors of determining depression severity in primary care; (2) GPs may equate risk of self-harm with suicidal intent; (3) educational initiatives need to focus on key depressive subtypes derived from emotional, somatic and associated symptoms.

Severity alone should no longer determine therapeutic choice in the management of depression in primary care: findings from a survey of general practitioners

BACKGROUND

The treatment of depression in primary care remains suboptimal for reasons that are complex and multifactorial. Typically GPs have to make difficult decisions in limited time and therefore, the aim of this study was to examine the management of depression of varying severity and the factors associated with treatment choices.

METHOD

Nested within a primary care educational initiative we conducted a survey of 1760 GPs. The GPs each identified four patients with clinical depression whom they had treated recently and then answered questions regarding their diagnosis and management of each patient.

RESULTS

Comorbid anxiety, sadness and decreased concentration appeared to direct the management of depression toward psychological therapy, whereas comorbid pain and a patient's overall functioning, such as the ability to do simple everyday activities, directed the initiation of pharmacological treatment. The use of antidepressants with a broader spectrum of actions (acting on multiple neurotransmitters) increased from mild to severe depression, whereas this did not occur with the more selective agents. SSRIs were prescribed more frequently compared with all other antidepressants, irrespective of depression severity.

LIMITATIONS

GPs chose the RADAR programme and therefore they were potentially more likely to have an interest in mental health compared to GPs who did not participate.

CONCLUSIONS

GPs do not appear to be determining pharmacological treatment based on depression subtype and specificity, but rather on the basis of the total number of symptoms and overall severity. While acknowledging important differences between primary care and specialist practice, it is suggested that guidelines to assist GPs in matching treatment to depression subtype may be of practical assistance in decision-making, and the delivery of more effective treatments.

Prevalence of psychotic symptoms in those with melancholic and nonmelancholic depression

The best classification of depressive disorders is still to be established. A melancholic subtype has a lengthy history, and recent research demonstrates its relevance. This study compares the prevalence of psychotic symptoms in nonmelancholic and melancholic depression and assesses whether there is a dimensional pattern in the severity of symptoms among the subtypes. Patients with unipolar depression were assessed for melancholic status, psychotic symptoms, and severity of depression. The diagnosis of melancholia was made by both Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR), criteria and CORE measure. The DSM criteria assigned a much higher percentage of patients as melancholics (67.4%) than did the CORE (24.9%). Prevalence of psychosis was distinctly higher in the melancholics. Symptoms severity was higher among the melancholics when compared with the nonmelancholics. The presence of psychotic symptoms was not associated with an increase in the intensity of depressive symptoms. Psychotic symptoms are more frequently associated with the melancholic subtype of depression. This suggests clinical contiguity between the melancholic and psychotic subtypes and the clinical relevance of identifying melancholia.

Pharmacometabolomics of response to sertraline and to placebo in major depressive disorder - possible role for methoxyindole pathway

Therapeutic response to selective serotonin (5-HT) reuptake inhibitors in Major Depressive Disorder (MDD) varies considerably among patients, and the onset of antidepressant therapeutic action is delayed until after 2 to 4 weeks of treatment. The objective of this study was to analyze changes within methoxyindole and kynurenine (KYN) branches of tryptophan pathway to determine whether differential regulation within these branches may contribute to mechanism of variation in response to treatment. Metabolomics approach was used to characterize early biochemical changes in tryptophan pathway and correlated biochemical changes with treatment outcome. Outpatients with MDD were randomly assigned to sertraline (n = 35) or placebo (n = 40) in a double-blind 4-week trial; response to treatment was measured using the 17-item Hamilton Rating Scale for Depression (HAMD₁₇). Targeted electrochemistry based metabolomic platform (LCECA) was used to profile serum samples from MDD patients. The response rate was slightly higher for sertraline than for placebo (21/35 [60%] vs. 20/40 [50%], respectively, χ²(1)  = 0.75, p = 0.39). Patients showing a good response to sertraline had higher pretreatment levels of 5-methoxytryptamine (5-MTPM), greater reduction in 5-MTPM levels after treatment, an increase in 5-Methoxytryptophol (5-MTPOL) and Melatonin (MEL) levels, and decreases in the (KYN)/MEL and 3-Hydroxykynurenine (3-OHKY)/MEL ratios post-treatment compared to pretreatment. These changes were not seen in the patients showing poor response to sertraline. In the placebo group, more favorable treatment outcome was associated with increases in 5-MTPOL and MEL levels and significant decreases in the KYN/MEL and 3-OHKY/MEL; changes in 5-MTPM levels were not associated with the 4-week response. These results suggest that recovery from a depressed state due to treatment with drug or with placebo could be associated with preferential utilization of serotonin for production of melatonin and 5-MTPOL.

Pharmacometabolomic mapping of early biochemical changes induced by sertraline and placebo

In this study, we characterized early biochemical changes associated with sertraline and placebo administration and changes associated with a reduction in depressive symptoms in patients with major depressive disorder (MDD). MDD patients received sertraline or placebo in a double-blind 4-week trial; baseline, 1 week, and 4 weeks serum samples were profiled using a gas chromatography time of flight mass spectrometry metabolomics platform. Intermediates of TCA and urea cycles, fatty acids and intermediates of lipid biosynthesis, amino acids, sugars and gut-derived metabolites were changed after 1 and 4 weeks of treatment. Some of the changes were common to the sertraline- and placebo-treated groups. Changes after 4 weeks of treatment in both groups were more extensive. Pathway analysis in the sertraline group suggested an effect of drug on ABC and solute transporters, fatty acid receptors and transporters, G signaling molecules and regulation of lipid metabolism. Correlation between biochemical changes and treatment outcomes in the sertraline group suggested a strong association with changes in levels of branched chain amino acids (BCAAs), lower BCAAs levels correlated with better treatment outcomes; pathway analysis in this group revealed that methionine and tyrosine correlated with BCAAs. Lower levels of lactic acid, higher levels of TCA/urea cycle intermediates, and 3-hydroxybutanoic acid correlated with better treatment outcomes in placebo group. Results of this study indicate that biochemical changes induced by drug continue to evolve over 4 weeks of treatment and that might explain partially delayed response. Response to drug and response to placebo share common pathways but some pathways are more affected by drug treatment. BCAAs seem to be implicated in mechanisms of recovery from a depressed state following sertraline treatment.

Meta-review of depressive subtyping models

BACKGROUND

Increasing dissatisfaction with the non-specificity of major depression has led many to propose more specific depressive subtyping models. The present meta-review seeks to map dominant depressive subtype models, and highlight definitions and overlaps.

METHODS

A database search in Medline and EMBASE of proposed depressive subtypes, and limited to reviews published between 2000 and 2011, was undertaken. Of the more than four thousand reviews, 754 were judged as potentially relevant and provided the base for the present selective meta-review.

RESULTS

Fifteen subtype models were identified. The subtypes could be divided into five molar categories of (1) symptom-based subtypes, such as melancholia, psychotic depression, atypical depression and anxious depression, (2) aetiologically-based subtypes, exemplified by adjustment disorders, early trauma depression, reproductive depression, perinatal depression, organic depression and drug-induced depression, (3) time of onset-based subtypes, as illustrated by early and late onset depression, as well as seasonal affective disorder, (4) gender-based (e.g. female) depression, and (5) treatment resistant depression. An overview considering definition, bio-psycho-social correlates and the evidence base of treatment options for each subtype is provided.

LIMITATIONS

Despite the large data base, this meta-review is nevertheless narrative focused.

CONCLUSIONS

Subtyping depression is a promising attempt to overcome the non-specificity of many diagnostic constructs such as major depression, both in relation to their intrinsic non-specificity and failure to provide treatment-specific information. If a subtyping model is to be advanced it would need, however, to demonstrate differential impacts of causes and treatments.

The interdependence of subtype and severity: contributions of clinical and neuropsychological features to melancholia and non-melancholia in an outpatient sample

Major depressive disorder is often considered to be a homogenous disorder that changes in terms of severity; however, the presence of distinct subtypes and a variety of presenting symptoms suggests much heterogeneity. Aiming to better understand the relationship between heterogeneity and diagnosis we used an exploratory approach to identify subtypes of depression on the basis of clinical symptoms and neuropsychological performance. Cluster analysis identified two groups of patients distinguished by level of cognitive dysfunction with the more severe cluster being associated with melancholic depression. While the relationship between cluster and subtype was significant, only 58% of melancholic patients were assigned to cluster 1 (the more severe cluster) and 66% of non-melancholic patients assigned to cluster 2. Subtypes also displayed a distinctive profile of impairment such that melancholic patients (n = 65) displayed more variability in attention while non-melancholic patients (n = 59) displayed memory recall impairment. While melancholia and non-melancholia are associated with a more severe and less severe form of depression respectively, findings indicate that differences between melancholia and non-melancholia are more than simple variation on severity. In summary, findings provide support for the heterogeneity of depression.

How Do People Taking Psychiatric Drugs Explain Their “Chemical Imbalance?”

Many people believe that chemical imbalances cause mental illnesses, despite the absence of evidence to ascertain this. This study describes the reasoning that people use in their own case to justify this belief. Data come from recorded medication histories with 22 adults aged 23–68 years, taking different psychiatric drugs for various problems and varying durations, asked directly if they thought their problem was caused by a chemical imbalance and to explain their answer. About two-thirds expressed belief that they had a chemical imbalance; and the rest that they did not have one, did not or could not know, or that their medication had caused one. Reasoning backward from positive drug experiences (ex juvantibus or post hoc) and appeals to authority and convention characterized most answers expressing belief in an imbalance. Experiencing improvement while taking drugs and acquiescing in mental health practitioners’ views instills or reinforces people’s belief that they are or were chemically imbalanced, which suggests viewing the belief as a drug effect. The chemical imbalance notion is likely to persist, as its appeal to give personal meaning to symptom relief and its unfalsifiability ensure institutional support that neutralizes the absence of scientific support.

The contribution of BDNF and 5-HTT polymorphisms and early life stress to the heterogeneity of major depressive disorder: a preliminary study

OBJECTIVE

Two reported genetic polymorphisms related to the production of brain-derived neurotrophic factor (BNDF) and reuptake by the serotonin transporter (5-HTT) appear to contribute to depression in combination with stressful life events. The aim of the current study was to investigate the contribution of early life stress (ELS), BDNF (Val versus Met alleles) and 5-HTT polymorphisms (L versus S alleles) to melancholic (n = 65) and non-melancholic depression (n = 59).

METHODS

A mediation approach ((G × G) × E mediation model) was employed to confirm the indirect effects of ELS on the relationship between 5-HTTPLR × BDNF polymorphism combinations and depression subtype. A series of binary logistic regressions were then conducted to determine whether genotype, ELS, and their interaction were able to predict depression subtype.

RESULTS

Key findings indicated that BDNF and 5-HTT polymorphisms in combination with ELS contributed to the development of non-melancholic depression. An interaction between BDNF and ELS increased the risk of non-melancholia by 3.327, whereas the interaction between 5-HTT and ELS increased risk by 2.406.

CONCLUSION

The results support a role for genetic factors in the development of non-melancholia. The lack of findings in melancholia indicates that other mechanisms may underlie the subtype. Alternatively, null findings may reflect a Type II error associated with a small sample size. Future studies should consider further examination of differential gene-environment interactions for melancholia versus non-melancholia.

Dopaminergic mechanisms of target detection - P300 event related potential and striatal dopamine

The P300 is a cortically generated event related potential (ERP) widely used in neurophysiological research since it is related to cognitive functions and central information processing. Intracerebral recordings and functional neuroimaging studies have demonstrated that this potential is generated by various brain regions including frontal, temporal and parietal cortices. Regarding the neurochemical background, clinical and genetic investigations suggest that dopaminergic neurons could be involved in the generation of the P300. However, there is no direct evidence in vivo that P300 amplitudes and latencies are related to dopaminergic parameters. The aim of this study was to further elucidate dopaminergic aspects of the P300 ERP by combining neurophysiological and nuclear medicine assessments in vivo. Patients with a major depressive episode underwent both P300 recordings and dynamic [¹²³I] IBZM SPECT for the evaluation of striatal dopamine D₂/D₃-receptor availability. There were statistically significant positive correlations of the striatal dopamine D₂/D₃-receptor status with P300 amplitudes and significant negative correlations with P300 latencies. Using this combined approach, the study presents direct evidence in vivo that the central dopaminergic system might play an important role in the generation of the P300 and that central dopaminergic activity could be involved in the modulation of P300 parameters. This association might be of relevance for the interpretation of P300 studies in psychiatric disorders.

Pretreatment metabotype as a predictor of response to sertraline or placebo in depressed outpatients: a proof of concept

The purpose of this study was to determine whether the baseline metabolic profile (that is, metabotype) of a patient with major depressive disorder (MDD) would define how an individual will respond to treatment. Outpatients with MDD were randomly assigned to sertraline (up to 150 mg per day) (N=43) or placebo (N=46) in a double-blind 4-week trial. Baseline serum samples were profiled using the liquid chromatography electrochemical array; the output was digitized to create a 'digital map' of the entire measurable response for a particular sample. Response was defined as ≥50% reduction baseline to week 4 in the 17-item Hamilton Rating Scale for Depression total score. Models were built using the one-out method for cross-validation. Multivariate analyses showed that metabolic profiles partially separated responders and non-responders to sertraline or to placebo. For the sertraline models, the overall correct classification rate was 81% whereas it was 72% for the placebo models. Several pathways were implicated in separation of responders and non-responders on sertraline and on placebo including phenylalanine, tryptophan, purine and tocopherol. Dihydroxyphenylacetic acid, tocopherols and serotonin were common metabolites in separating responders and non-responders to both drug and placebo. Pretreatment metabotypes may predict which depressed patients will respond to acute treatment (4 weeks) with sertraline or placebo. Some pathways were informative for both treatments whereas other pathways were unique in predicting response to either sertraline or placebo. Metabolomics may inform the biochemical basis for the early efficacy of sertraline.

Anhedonia in Parkinson's disease: a systematic review of the literature

Anhedonia, defined as lowered ability to experience physical or social pleasure, is a key symptom of several psychiatric illnesses. In this systematic review, we aimed to evaluate the role of anhedonia in Parkinson's Disease and its relationships with other clinical characteristics, dopamine dysfunction, and antiparkinsonian therapy. The database was selected using PubMed Services. Relevant journals were hand-searched, and the bibliographies of all the important articles were scrutinized to find additional publications. Fifteen studies assessed the topic of anhedonia in Parkinson's disease from 1984 to 2009 and mainly described it as a core symptom of depression in patients with Parkinson's disease. Some studies investigated the relationship between anhedonia and neuropsychological symptoms and found correlations with frontal lobe functions. Reports on the relationship between anhedonia and illness severity or motor symptoms are rather inconclusive. No definitive conclusions can be drawn because few studies have been published on this topic. Nevertheless, some evidence suggests that in Parkinson's disease anhedonia is a secondary phenomenon linked to depression, apathy severity, and frontal lobe dysregulation and that it could respond to antiparkinsonian treatment. Future studies of larger samples of patients are strongly required to definitively clarify the relationship between anhedonia and other clinical features, such as depression, anxiety, apathy, cognition, and motor status. Furthermore, more reliable tools and validated diagnostic criteria are necessary to assess anhedonia in patients with Parkinson's disease.

Glutamate cysteine ligase (GCL) and self reported depression: an association study from the HUNT

BACKGROUND

There is increasing evidence suggesting oxidative stress may play a role in the aetiology of depression. Glutathione is the brain's predominant free radical scavenger, and associated polymorphisms of the glutamate cysteine ligase (GCL) gene have been reported for related psychiatric disorders. The aim of the study was to investigate candidate polymorphisms of GCL validated in schizophrenia and their association with current state depression, as measured by the Hospital Anxiety and Depression Scale (HADS).

METHODS

Polymorphisms were genotyped on 983 cases and 967 controls selected from a population sample of adults participating in the Nord-Trøndelag Health Study. Cases were the top scoring individuals (98.5th percentile) on the HADS depression subscale while the controls were randomly selected from below this cut-off. The polymorphisms comprised three SNPs from GCLM, the gene encoding the GCL modifier and 9 SNPs plus a trinucleotide repeat (TNTR) from intron 1 and the 5'UTR of GCLC, the gene encoding the GCL catalytic subunit. Using the linkage disequilibrium between the GCLC markers we also tested whether SNPs could represent the variation of the TNTR.

RESULTS

The candidate polymorphisms showed no evidence for association with depression. The C allele of SNP rs9474592 is coupled with the 9 GAG repeats allele of the TNTR, r²=0.81. None of the other SNPs either individually or as two or three-SNP haplotypes was associated with the TNTR alleles.

LIMITATIONS

Depression was self-reported and measured at one time point.

CONCLUSIONS

This study provides no evidence to suggest that polymorphisms of GCL are associated with self-reported depression.

Does psychomotor retardation define a clinically relevant phenotype of unipolar depression?

BACKGROUND

The recognition and assessment of psychomotor retardation may have implications for better definition of the clinical phenotypes of depression. The aim of this study was to assess the clinical correlates of psychomotor retardation endorsed at any time during the patients' lifetime (LPR).

METHODS

The study sample included 291 patients with non-psychotic major depressive disorder (MDD) participating in the clinical trial, "Depression: The Search for Treatment-Relevant Phenotypes." Psychomotor retardation was measured using a factor derived from the Mood Spectrum Self-Report (MOODS-SR) assessment. Using a pre-defined cut-off score on the lifetime psychomotor retardation (LPR) factor of the MOODS-SR, participants were classified into high and low scorers. Logistic regression analysis was used to evaluate the relationship between LPR and subthreshold bipolarity.

RESULTS

Compared to low scorers, participants with high scores on the LPR factor had greater severity of depression and more bipolarity indicators.

CONCLUSIONS

The MOODS-SR appears to be helpful to identify clinical phenotypes of unipolar depression and to highlight the usefulness of a lifetime approach to the assessment of psychopathology in the characterisation of patients with unipolar depression.

Thalamocortical changes in major depression probed by deconvolution and physiology-based modeling

Auditory event-related potentials (ERPs) have been extensively studied in patients with depression, but most studies have focused on purely phenomenological analysis methods, such as component scoring. In contrast, this study applies two recently developed physiology-based methods-fitting using a thalamocortical model of neuronal activity and waveform deconvolution - to data from a selective-attention task in four subject groups (49 patients with melancholic depression, 34 patients with non-melancholic depression, 111 participants with subclinical depressed mood, and 98 healthy controls), to yield insight into physiological differences in attentional processing between participants with major depression and controls. This approach found evidence that: participants with depressed mood, regardless of clinical status, shift from excitation in the thalamocortical system towards inhibition; that clinically depressed participants have decreased relative response amplitude between target and standard waveforms; and that patients with melancholic depression also have increased thalamocortical delays. These findings suggest possible physiological mechanisms underlying different depression subtypes, and may eventually prove useful in motivating new physiology-based diagnostic methods.

Impact of depression heterogeneity on attention: an auditory oddball event related potential study

BACKGROUND

Major depressive disorder is associated with a reduced ability to attend and concentrate, however, the extent to which attentional impairment is dependent on subtype remains to be clarified.

METHODS

Event-related potentials (ERPs) associated with a well-validated auditory oddball, selective attention task, were recorded to determine the impact of melancholia (n=57) versus non-melancholia (n=48) relative to controls (n=116).

RESULTS

The key findings were an exaggeration of the P200 to both non-target and target stimuli and a reduction in the P300 to targets in patients with melancholia, relative to patients with non-melancholia and controls. In addition, the N200/P300 complex was slowed in latency corresponding to the slowed behavioural responses to targets in melancholia. Stepwise regression analysis also revealed that depression severity, but not psychomotor slowing, contributed to increases in P200 amplitude.

LIMITATIONS

This study is cross-sectional and cannot determine whether the observed ERP changes are a state or trait marker, highlighting the need for a longitudinal study of ERP characteristics in different subgroups of depressed patients.

CONCLUSIONS

Results point to a difficulty in differentiating significant stimuli in the environment in the depressed individual. The combined disruption of early sensory processing (P200) and subsequent context processing (N200/P300 complex) may provide a potential mechanism for the attentional impairment that is frequently observed in depression, particularly in more severe depression.