Development Of Major Depressive Disorder Research Articles

Disturbed diurnal rhythm of three classical phase markers in the chronic mild stress rat model of depression

Disturbances of circadian rhythms have been suggested to be a causal factor in the development of major depressive disorder. However, the mechanisms underlying the association between circadian rhythm abnormalities and mood disorders are still unknown. In the current study the association between diurnal pattern of key phase markers (melatonin, corticosterone, and core body temperature) and anhedonic-like behavior was investigated using the highly validated rat chronic mild stress (CMS) model of depression. Phase marker measurements were done after 3.5 weeks of CMS in 48 control rats and 48 anhedonic-like rats at 6 time points within 24h. The results showed that anhedonic-like behavior associates with changes in all three phase markers: an increased dark phase melatonin secretion, an additional peak in corticosterone level in the beginning of the light phase, and hypothermia in the dark phase. The result adds to the validity of the CMS model in general and in particular to be adequate as a model for studying the chronobiology of depressive disorder.

The role of obesity measures in the development and persistence of major depressive disorder

BackgroundThe role of obesity with the development of major depressive disorder (MDD) requires conformation and whether obesity contributes to more chronic depression in persons with established (MDD) is unknown. This study examined the longitudinal relationship of body mass index (BMI) and waist circumference with the incidence and persistence of MDD over 2-year and 6-year periods. MethodData were sourced from the Netherlands Study of Depression and Anxiety. MDD was established with Composite International Diagnostic Interviews. The relationship of BMI and waist circumference with the development of depression two and six years later were estimated in the subsample with no current psychopathology at baseline. Associations with the persistence of depression was estimated in the subsample with current MDD. ResultsHigher BMI at baseline, but not waist circumference, slightly increased the odds of the development of MDD after two years (odds ratio (OR) per standard deviation increase: 1.11; p=0.03), This relationship was not significant after adjustment for health and lifestyle variables. Conversely, over a 6-year period both BMI and waist circumference moderately increased the odds of developing MDD even after adjustment (OR:1.17; p=0.05, OR:1.20; p=0.05). Persistence of MDD in currently depressed subjects, is not related with BMI or waist circumference (adjusted OR:0.93; p=0.2, OR:0.91; p=0.15). LimitationsDevelopment of depression may differ in participants lost to follow-up. ConclusionOver a 6 year period, patients with higher BMI show a slightly increased risk of development of depression. However, in depressed patients there is no relationship between BMI and the persistence of depression.

Poster Number: EI 7 - Cognitive Impairment Predicts Subsequent Development of Major Depressive Disorder in the Elderly: An 8-Year Prospective Study in Chile

Poster Number: EI 7 - Cognitive Impairment Predicts Subsequent Development of Major Depressive Disorder in the Elderly: An 8-Year Prospective Study in Chile

Neural correlates of self-perceptions in adolescents with major depressive disorder

Alteration in self-perception is a salient feature in major depression. Hyperactivity of anterior cortical midline regions has been implicated in this phenomenon in depressed adults. Here, we extend this work to depressed adolescents during a developmental time when neuronal circuitry underlying the sense of self matures by using task-based functional magnetic resonance imaging (fMRI) and connectivity analyses. Twenty-three depressed adolescents and 18 healthy controls (HC) viewed positive and negative trait words in a scanner and judged whether each word described them (‘self’ condition) or was a good trait to have (‘general’ condition). Self-perception scores were based on participants’ endorsements of positive and negative traits during the fMRI task. Depressed adolescents exhibited more negative self-perceptions than HC. Both groups activated cortical midline regions in response to self-judgments compared to general-judgments. However, depressed adolescents recruited the posterior cingulate cortex/precuneus more for positive self-judgments. Additionally, local connectivity of the dorsal medial prefrontal cortex was reduced during self-reflection in depressed adolescents. Our findings highlight differences in self-referential processing network function between depressed and healthy adolescents and support the need for further investigation of brain mechanisms associated with the self, as they may be paramount to understanding the etiology and development of major depressive disorder.

Affective temperaments play an important role in the relationship between childhood abuse and depressive symptoms in major depressive disorder

Previous studies have shown that various factors, such as genetic and environmental factors, contribute to the development of major depressive disorder (MDD). The aim of this study is to clarify how multiple factors, including affective temperaments, childhood abuse and adult life events, are involved in the severity of depressive symptoms in MDD. A total of 98 participants with MDD were studied using the following self-administered questionnaire surveys: Patient Health Questionnaire-9 measuring the severity of depressive symptoms; Life Experiences Survey (LES) measuring negative and positive adult life events; Temperament Evaluation of the Memphis, Pisa, Paris, and San Diego auto-questionnaire (TEMPS-A) measuring affective temperaments; and the Child Abuse and Trauma Scale (CATS) measuring childhood abuse. The data were analyzed using single and multiple regression analyses and structural equation modeling (SEM). The neglect score reported by CATS indirectly predicted the severity of depressive symptoms through affective temperaments measured by TEMPS-A in SEM. Four temperaments (depressive, cyclothymic, irritable, and anxious) directly predicted the severity of depressive symptoms. The negative change in the LES score also directly predicted severity. This study suggests that childhood abuse, especially neglect, indirectly increases the severity of depressive symptoms through increased scores of affective temperaments in MDD.

Antioxidant treatment ameliorates experimental diabetes-induced depressive-like behaviour and reduces oxidative stress in brain and pancreas.

Studies have shown a relationship between diabetes mellitus (DM) and the development of major depressive disorder. Alterations in oxidative stress are associated with the pathophysiology of both diabetes mellitus and major depressive disorder. This study aimed to evaluate the effects of antioxidants N-acetylcysteine and deferoxamine on behaviour and oxidative stress parameters in diabetic rats. To this aim, after induction of diabetes by a single dose of alloxan, Wistar rats were treated with N-acetylcysteine or deferoxamine for 14 days, and then depressive-like behaviour was evaluated. Oxidative stress parameters were assessed in the prefrontal cortex, hippocampus, amygdala, nucleus accumbens and pancreas. Diabetic rats displayed depressive-like behaviour, and treatment with N-acetylcysteine reversed this alteration. Carbonyl protein levels were increased in the prefrontal cortex, hippocampus and pancreas of diabetic rats, and both N-acetylcysteine and deferoxamine reversed these alterations. Lipid damage was increased in the prefrontal cortex, hippocampus, amygdala and pancreas; however, treatment with N-acetylcysteine or deferoxamine reversed lipid damage only in the hippocampus and pancreas. Superoxide dismutase activity was decreased in the amygdala, nucleus accumbens and pancreas of diabetic rats. In diabetic rats, there was a decrease in catalase enzyme activity in the prefrontal cortex, amygdala, nucleus accumbens and pancreas, but an increase in the hippocampus. Treatment with antioxidants did not have an effect on the activity of antioxidant enzymes. In conclusion, animal model of diabetes produced depressive-like behaviour and oxidative stress in the brain and periphery. Treatment with antioxidants could be a viable alternative to treat behavioural and biochemical alterations induced by diabetes.

Decreased SGK1 Expression and Function Contributes to Behavioral Deficits Induced by Traumatic Stress.

Exposure to extreme stress can trigger the development of major depressive disorder (MDD) as well as post-traumatic stress disorder (PTSD). The molecular mechanisms underlying the structural and functional alterations within corticolimbic brain regions, including the prefrontal cortex (PFC) and amygdala of individuals subjected to traumatic stress, remain unknown. In this study, we show that serum and glucocorticoid regulated kinase 1 (SGK1) expression is down-regulated in the postmortem PFC of PTSD subjects. Furthermore, we demonstrate that inhibition of SGK1 in the rat medial PFC results in helplessness- and anhedonic-like behaviors in rodent models. These behavioral changes are accompanied by abnormal dendritic spine morphology and synaptic dysfunction. Together, the results are consistent with the possibility that altered SGK1 signaling contributes to the behavioral and morphological phenotypes associated with traumatic stress pathophysiology.

Apigenin ameliorates chronic mild stress-induced depressive behavior by inhibiting interleukin-1β production and NLRP3 inflammasome activation in the rat brain

Increasing evidence suggests that inflammation and oxidative stress may contribute to the development of major depressive disorder (MDD). Apigenin, a type of bioflavonoid widely found in citrus fruits, has a number of biological actions including anti-inflammatory and antioxidant effects. Although apigenin has potential antidepressant activity, the mechanisms of this effect remain unclear. The present study aims to investigate the effects of apigenin on behavioral changes and inflammatory responses induced by chronic unpredictable mild stress (CUMS) in rats. GW9662, a selective peroxisome proliferator-activated receptor gamma (PPARγ) inhibitor, was administered 30min before apigenin. We found that treatment with apigenin (20mg/kg, intragastrically) for three weeks remarkably ameliorated CUMS-induced behavioral abnormalities, such as decreased locomotor activity and reduced sucrose consumption. In response to oxidative stress, the NLRP3 inflammasome was activated and IL-1β secretion increased in the prefrontal cortex (PFC) of CUMS rats. However, apigenin treatment upregulated PPARγ expression and downregulated the expression of NLRP3, which subsequently downregulated the production of IL-1β. In addition, GW9662 diminished the inhibitory effects of apigenin on the NLRP3 inflammasome. In conclusion, our results demonstrate that apigenin exhibits antidepressant-like effects in CUMS rats, possibly by inhibiting IL-1β production and NLRP3 inflammasome expression via the up-regulation of PPARγ expression.

Pre-stress performance in an instrumental training predicts post-stress behavioral alterations in chronically stressed rats.

Stress is a major factor in the development of major depressive disorder (MDD), but few studies have assessed individual risk based on pre-stress behavioral and cognitive traits. To address this issue, we employed appetitive instrumental lever pressing with a progressive ratio (PR) schedule to assess these traits in experimentally naïve Sprague-Dawley rats. Based on four distinct traits that were identified by hierarchical cluster analysis, the animals were classified into the corresponding four subgroups (Low Motivation, Quick Learner, Slow Learner, and Hypermotivation), and exposed to chronic unpredictable stress (CUS) before monitoring their post-stress responses for 4 weeks. The four subgroups represented the following distinct behavioral phenotypes after CUS: the Low Motivation subgroup demonstrated weight loss and a late-developing paradoxical enhancement in PR performance that may be related to inappropriate decision-making in human MDD. The Quick Learner subgroup exhibited a transient loss of motivation and the habituation of serum corticosterone (CORT) response to repeated stress. The Slow Learner subgroup displayed resistance to demotivation and a suppressed CORT response to acute stress. Finally, the Hypermotivation subgroup exhibited resistance to weight loss, habituated CORT response to an acute stress, and a long-lasting amotivation. Overall, we identified causal relationships between pre-stress traits in the performance of the instrumental training and post-stress phenotypes in each subgroup. In addition, many of the CUS-induced phenotypes in rats corresponded to or had putative relationships with representative symptoms in human MDD. We concluded that the consequences of stress may be predictable before stress exposure by determining the pre-stress behavioral or cognitive traits of each individual in rats.

Early life environmental and pharmacological stressors result in persistent dysregulations of the serotonergic system.

Dysregulations in the brain serotonergic system and exposure to environmental stressors have been implicated in the development of major depressive disorder. Here, we investigate the interactions between the stress and serotonergic systems by characterizing the behavioral and biochemical effects of chronic stress applied during early-life or adulthood in wild type (WT) mice and mice with deficient tryptophan hydroxylase 2 (TPH2) function. We showed that chronic mild stress applied in adulthood did not affect the behaviors and serotonin levels of WT and TPH2 knock-in (KI) mice. Whereas, maternal separation (MS) stress increased anxiety- and depressive-like behaviors of WT mice, with no detectable behavioral changes in TPH2 KI mice. Biochemically, we found that MS WT mice had reduced brain serotonin levels, which was attributed to increased expression of monoamine oxidase A (MAO A). The increased MAO A expression was detected in MS WT mice at 4 weeks old and adulthood. No change in TPH2 expression was detected. To determine whether a pharmacological stressor, dexamethasone (Dex), will result in similar biochemical results obtained from MS, we used an in vitro system, SH-SY5Y cells, and found that Dex treatment resulted in increased MAO A expression levels. We then treated WT mice with Dex for 5 days, either during postnatal days 7–11 or adulthood. Both groups of Dex treated WT mice had reduced basal corticosterone and glucocorticoid receptors expression levels. However, only Dex treatment during PND7–11 resulted in reduced serotonin levels and increased MAO A expression. Just as with MS WT mice, TPH2 expression in PND7–11 Dex-treated WT mice was unaffected. Taken together, our findings suggest that both environmental and pharmacological stressors affect the expression of MAO A, and not TPH2, when applied during the critical postnatal period. This leads to long-lasting perturbations in the serotonergic system, and results in anxiety- and depressive-like behaviors.

Understanding the candidate gene × environment interaction debate: epistemological or evidential divide?

Understanding the candidate gene × environment interaction debate: epistemological or evidential divide?

The Impact of Caregiving on the Development of Major Depressive Disorder and Generalized Anxiety Disorder

Providing care for a relative is associated with psychological distress and a higher prevalence of psychological disorders. This study investigated the prevalence of anxiety and depressive disorders among the caregiving population. The study was based on data drawn from the Collaborative Psychiatric Epidemiology Surveys (CPES). Binary logistic regressions were conducted to examine these associations and to identify factors influencing the development of depressive and anxiety disorders. The analysis indicated that respondents providing care for a relative were at a higher risk of developing a psychological disorder. A number of socio-demographic variables were identified as increasing the risk of developing a psychological disorder such as being younger, female and divorced. The findings highlight the importance of support and interventions for family caregivers.

Psychiatric Disorders in Childhood and the Risk of Later Major Depressive Disorder

Introduction An association between psychiatric disorders in childhood and the later development of major depressive disorders (MDD) has been suggested. However, no prospective population-based cohort study has been able to directly compare the risks of MDD following a broad spectrum of child and adolescent psychiatric disorders. Aims To use a large, register-based cohort to establish whether or not psychiatric disorders in childhood lead to a higher risk of later MDD and, if so, which disorders are associated with the highest risks. Objectives To estimate and compare the risk of later MDD in children diagnosed with one of ten psychiatric disorders Methods Using Danish population-based registers all persons born in Denmark from 1990 through 2000 were identified and followed from their 5 th birthday through 2012. Cumulative incidences and incidence rate ratios of MDD following each of ten exposure disorders were calculated Results We followed 960,026 persons, contributing 8,778,331 person-years. Among these 7,787 were diagnosed with MDD (incidence=1.7/1000 pyrs). Diagnosis of any psychiatric disorder led to an absolute risk of MDD within eight years of 1.6% in males and 4.98% in females with early onset (ages 0-14) and 7.02% in males and 15.98% in females with late onset (ages 14-18). For all groups, anxiety and eating disorders were associated with the highest risks of MDD. Conclusions Most disorders were associated with a significantly increased risk of later MDD and children with anxiety and eating disorders carry the greater risk. Future research should focus on common pathways between depression and other psychiatric disorders.

The Role of Nutrients in Protecting Mitochondrial Function and Neurotransmitter Signaling: Implications for the Treatment of Depression, PTSD, and Suicidal Behaviors

Numerous studies have linked severe stress to the development of major depressive disorder (MDD) and suicidal behaviors. Furthermore, recent preclinical studies from our laboratory and others have demonstrated that in rodents, chronic stress and the stress hormone cortisol cause oxidative damage to mitochondrial function and membrane lipids in the brain. Mitochondria play a key role in synaptic neurotransmitter signaling by providing adenosine triphosphate (ATP), mediating lipid and protein synthesis, buffering intracellular calcium, and regulating apoptotic and resilience pathways. Membrane lipids are similarly essential to central nervous system (CNS) function because cholesterol, polyunsaturated fatty acids, and sphingolipids form a lipid raft region, a special lipid region on the membrane that mediates neurotransmitter signaling through G-protein-coupled receptors and ion channels. Low serum cholesterol levels, low antioxidant capacity, and abnormal early morning cortisol levels are biomarkers consistently associated with both depression and suicidal behaviors. In this review, we summarize the manner in which nutrients can protect against oxidative damage to mitochondria and lipids in the neuronal circuits associated with cognitive and affective behaviors. These nutrients include ω3 fatty acids, antioxidants (vitamin C and zinc), members of the vitamin B family (Vitamin B12 and folic acid), and magnesium. Accumulating data have shown that these nutrients can enhance neurocognitive function, and may have therapeutic benefits for depression and suicidal behaviors. A growing body of studies suggests the intriguing possibility that regular consumption of these nutrients may help prevent the onset of mood disorders and suicidal behaviors in vulnerable individuals, or significantly augment the therapeutic effect of available antidepressants. These findings have important implications for the health of both military and civilian populations.

Poster #S39 ENDOGENOUS TESTOSTERONE LEVELS ARE ASSOCIATED WITH NEURAL ACTIVITY IN MEN WITH SCHIZOPHRENIA DURING A FACIAL EMOTION PROCESSING TASK

Alteration in self-perception is a salient feature in major depression. Hyperactivity of anterior cortical midline regions has been implicated in this phenomenon in depressed adults. Here, we extend this work to depressed adolescents during a developmental time when neuronal circuitry underlying the sense of self matures by using task-based functional magnetic resonance imaging (fMRI) and connectivity analyses. Twenty-three depressed adolescents and 18 healthy controls (HC) viewed positive and negative trait words in a scanner and judged whether each word described them (‘self’ condition) or was a good trait to have (‘general’ condition). Self-perception scores were based on participants’ endorsements of positive and negative traits during the fMRI task. Depressed adolescents exhibited more negative self-perceptions than HC. Both groups activated cortical midline regions in response to self-judgments compared to general-judgments. However, depressed adolescents recruited the posterior cingulate cortex/precuneus more for positive self-judgments. Additionally, local connectivity of the dorsal medial prefrontal cortex was reduced during self-reflection in depressed adolescents. Our findings highlight differences in self-referential processing network function between depressed and healthy adolescents and support the need for further investigation of brain mechanisms associated with the self, as they may be paramount to understanding the etiology and development of major depressive disorder.

Hypermethylation in the ZBTB20 gene is associated with major depressive disorder

BackgroundAlthough genetic variation is believed to contribute to an individual’s susceptibility to major depressive disorder, genome-wide association studies have not yet identified associations that could explain the full etiology of the disease. Epigenetics is increasingly believed to play a major role in the development of common clinical phenotypes, including major depressive disorder.ResultsGenome-wide MeDIP-Sequencing was carried out on a total of 50 monozygotic twin pairs from the UK and Australia that are discordant for depression. We show that major depressive disorder is associated with significant hypermethylation within the coding region of ZBTB20, and is replicated in an independent cohort of 356 unrelated case-control individuals. The twins with major depressive disorder also show increased global variation in methylation in comparison with their unaffected co-twins. ZBTB20 plays an essential role in the specification of the Cornu Ammonis-1 field identity in the developing hippocampus, a region previously implicated in the development of major depressive disorder.ConclusionsOur results suggest that aberrant methylation profiles affecting the hippocampus are associated with major depressive disorder and show the potential of the epigenetic twin model in neuro-psychiatric disease.

Changes in cortical thickness across the lifespan in major depressive disorder

Neurobiological mechanisms underlying the development of major depressive disorder (MDD) may differ depending on age-of-onset. Our aim was to compare patients who differ in age-of-onset, while controlling for illness duration, and number of depressive episodes. By directly comparing early-(EOD) and late-onset (LOD) patients, we examined whether age-of-onset is associated with changes in the extent or spatial pattern of cortical thickness. Cross-sectional comparison of cortical thickness in EOD vs. LOD. Age-of-onset was determined based on self-report, with EOD defined as onset prior to age 25. Reduced cortical thickness in the dorsal–lateral prefrontal cortex (DLPFC), pre- and postcentral gyrus, and the lingual gyrus were found in EOD compared to healthy controls (p<0.001). In linear regression models controlling for number of episodes, illness duration, severity, and sex, differences (at p<0.001) were found between EOD and LOD in the bilateral posterior cingulate, parahippocampal gyri, right precuneus, lingual, and fusiform gyri, but not the DLPFC. EOD is associated with greater disturbances in cortical thickness than LOD, even when duration of illness and other factors are controlled. These results provide novel insights on how development of depression is differentiated by age.

Gene—Environment Interactions in Major Depressive Disorder

Family, twin, and epidemiologic studies have suggested that both genes and environment are important risk factors for the development of major depressive disorder (MDD). In the absence of consistent and strong main genetic effects, numerous studies have supported gene-environment interactions in this disorder. While the impact of negative environmental factors, such as early life stress, traumatic experiences, and negative life events have been established as risk factors, they are not sufficient to predict MDD. This article will review evidence suggesting that genetic variants moderate the effects of adversities on the development of MDD, with a focus on the importance of careful characterization of the stressful life events as well as systemic and molecular mechanisms that potentially mediate these gene-environment interactions.

Drugs in Clinical Development for Major Depressive Disorder

Drugs in Clinical Development for Major Depressive Disorder

Identification of the Cytochrome P450 and Other Enzymes Involved in the In Vitro Oxidative Metabolism of a Novel Antidepressant, Lu AA21004

1-[2-(2,4-Dimethyl-phenylsulfanyl)-phenyl]-piperazine (Lu AA21004) is a novel antidepressant that is currently in late-stage clinical development for major depressive disorder. In the present study, the metabolism of Lu AA21004 was investigated using human liver microsomes (HLM), human liver S9 fraction, and recombinant enzymes. Lu AA21004 was found in vitro to be oxidized to a 4-hydroxy-phenyl metabolite, a sulfoxide, an N-hydroxylated piperazine, and a benzylic alcohol, which was further oxidized to the corresponding benzoic acid [3-methyl-4-(2-piperazin-1-yl-phenysulfanyl)-benzoic acid (Lu AA34443)]. The formation of the 4-hydroxy-phenyl metabolite was catalyzed by CYP2D6 with some contribution from CYP2C9, whereas the formation of the sulfoxide was mediated by CYP3A4/5 and CYP2A6. CYP2C9 and CYP2C19 were the primary enzymes responsible for formation of the N-hydroxylated metabolite. The benzylic alcohol was formed by CYP2D6 only. The oxidation of the benzylic alcohol to the corresponding benzoic acid of Lu AA21004 was catalyzed by alcohol dehydrogenase and aldehyde dehydrogenase, with some contribution from aldehyde oxidase. CYP2D6 was also capable of catalyzing the formation of the benzoic acid of Lu AA21004; however, its overall contribution to this pathway was negligible. Enzyme kinetic parameters revealed that the rate-limiting step in the formation of the benzoic acid from Lu AA21004 is the formation of the corresponding alcohol. Thus, the intrinsic clearance (V(max)/K(m)) in HLM for metabolism of Lu AA21004 to the benzylic alcohol was 1.13 × 10(-6) l · min(-1) · mg(-1), whereas the subsequent metabolism of the benzylic alcohol to the benzoic acid of Lu AA21004 is characterized by an intrinsic clearance (V(max)/K(m)) in S9 fraction of 922 × 10(-6) l · min(-1) · mg(-1).