Study of the Serum Copper Levels in Patients with Major Depressive Disorder

Copper may be involved in the pathophysiology of depression. Clinical data on this issue are very limited and not conclusive. The purpose of the study was to determine the copper concentration in the serum of patients with major depressive disorder and to discuss its potential clinical usefulness as a biomarker of the disease. A case–control clinical study included 69 patients with current depressive episode, 45 patients in remission and 50 healthy volunteers. Cu concentration was measured by electrothermal atomic absorption spectrometry (ETAAS). The mean serum copper level in depressed patients was slightly lower (by 11 %; not statistically significant) than in the control group. Furthermore, there was no significant difference in Cu²⁺ concentration between depressive episode and remission, nor between remission and control group. In the remission group were observed significant correlations between copper levels and the average number of relapses over the past years or time of remission. There was no correlation between serum copper and severity of depression, as measured by HDRS and MADRS. The obtained results showed no significant differences between the copper concentration in the blood serum of patients (both with current depressive episode and in remission) and healthy volunteers, as well as the lack of correlations between the copper level in the active stage of the disease and clinical features of the population. Our study is the first conducted on such a large population of patients, so the results may be particularly important and reliable source of knowledge about the potential role of copper in depression.     

The Impacts of Migraine among Outpatients with Major Depressive Disorder at a Two-Year Follow-Up

BackgroundNo study has investigated the impacts of migraine on depression, anxiety, and somatic symptoms and remission at the two-year follow-up point among patients with major depressive disorder (MDD). This study aimed to investigate the above issues.MethodsPsychiatric outpatients with MDD recruited at baseline were investigated at a two-year follow-up (N = 106). The Hamilton Depression Rating Scale, Hospital Anxiety and Depression Scale, and Depression and Somatic Symptoms Scale were used. Migraine was diagnosed according to the International Classification of Headache Disorders, 2^nd edition. The patients were divided into no migraine, inactive migraine, and active migraine subgroups. Multiple logistic regressions were used to investigate the significant factors related to full remission of depression.ResultsAmong patients without pharmacotherapy at the follow-up, patients with active migraine had significantly greater severities of anxiety and somatic symptoms as compared with patients without migraine; moreover, patients with active migraine had the lowest improvement percentage and full remission rate. There were no significant differences in depression, anxiety, and somatic symptoms between patients with inactive migraine and those without migraine. Active headache at follow-up was a significant factor related to a lower full remission rate.ConclusionsActive headache at follow-up was associated with a lower rate of full remission and more residual anxiety and somatic symptoms at follow-up among patients with migraine. Physicians should integrate a treatment plan for depression and migraine for the treatment of patients with MDD.     

Near Infrared Spectroscopy Study of the Frontopolar Hemodynamic Response and Depressive Mood in Children with Major Depressive Disorder: A Pilot Study

AIM

The aim of this study was to evaluate the frontopolar hemodynamic response and depressive mood in children with mild or moderate major depressive disorder during six weeks treatment without medication.

METHODS

The subjects were 10 patients with mild or moderate depression. They were depressive drug-naive children and adolescents. The scores of Depression Self Rating Scale (DSRS), the results of the Verbal Fluency Test (VFT), and the concentrations of oxy-hemoglobin (Oxy-Hb) of frontal pole brain assessed by two-channel near infrared spectroscopy (NIRS) after six weeks of treatment was compared with those of initial treatment.

RESULTS

The score of DSRS was significantly reduced after six weeks of initial treatment (p<0.001, t-test). The word number of VFT was not significantly changed after six weeks of treatment. The oxy-Hb concentration significantly increased after six weeks of treatment (p<0.001, t-test).

CONCLUSIONS

This study demonstrated that the concentration of oxy-Hb of frontopolar cortex in children with mild and moderate depression improved along with their depressive mood. These results suggested that concentration of oxy-Hb using NIRS may be used as the state maker for change in depressive mood of children having depression, similar to that in adults.     

Identification of Differential MicroRNAs in Cerebrospinal Fluid and Serum of Patients with Major Depressive Disorder

Major depression is a debilitating disease. To date, the development of biomarkers of major depressive disorder (MDD) remains a challenge. Recently, alterations in the expression of microRNAs (miRNAs) from post-mortem brain tissue and peripheral blood have been linked to MDD. The goals of this study were to detect the differential miRNAs in cerebrospinal fluid (CSF) and serum of MDD patients. First, the relative expression levels of 179 miRNAs (relative high levels in serum) were analyzed by miRNA PCR Panel in the CSF of MDD patients. Then, the differentially altered miRNAs from CSF were further assessed by qRT-PCR in the serum of the same patients. Finally, the serum differentially altered miRNAs were further validated by qRT-PCR in the serum of another MDD patients. The CSF-results indicated that 11 miRNAs in MDD patients were significantly higher than these in control subjects, and 5 miRNAs were significantly lower than these in control subjects. The serum-results from the same patients showed that 3 miRNAs (miR-221-3p, miR-34a-5p, and let-7d-3p) of the 11 miRNAs were significantly higher than these in control subjects, and 1 miRNA (miR-451a) of 5 miRNAs was significantly lower than these in control subjects. The up-regulation of miR-221-3p, miR-34a-5p, let-7d-3p and down-regulation of miR-451a was further validated in another 32 MDD patients. ROC analysis showed that the area under curve of let-7d-3p, miR-34a-5p, miR-221-3p and miR-451a was 0.94, 0.98, 0.97 and 0.94, with specificity of 90.48%, 95.24%, 90.48% and 90.48%, and sensitivity of 93.75%, 96.88%, 90.63% and 84.85%, respectively. In addition, target gene prediction found that the altered miRNAs are involved in affecting some important genes and pathway related to MDD. Our results suggested that differentially altered miRNAs in CSF might be involved in MDD, and serum miR-221-3p, miR-34a-5p, let-7d-3p, and miR-451a might be able to serve as biomarkers for MDD.     

Waist-to-Hip Ratio,Dyslipidemia, Glycemic Levels,Blood Pressure and Depressive Symptoms among Diabetic and Non-Diabetic Chinese Women: A Cross-Sectional Study

Objectives

To explore the relationship between depressive symptoms and waist-to-hip ratio, dyslipidemia, glycemic levels or blood pressure among diabetic and non-diabetic Chinese women.

Methods

11,908 women aged ≥40 years were enrolled in this cross-sectional study, including 2,511 with type 2 diabetes and 9,397 without. Depressive symptoms (defined as having mild-to-severe depressive symptoms) were assessed by the Patient Health Questionnaire-9 (PHQ-9) diagnostic algorithm. The prevalence and the odds ratios (ORs) with 95% confidence intervals (CIs) for having depressive symptoms were estimated using logistic regression analysis.

Results

The age-adjusted prevalence of depressive symptoms was significantly higher in non-diabetic subjects with waist-to-hip ratio (WHR) ≥0.9 (8.6%, age-adjusted OR 1.51 [95% CI 1.17, 1.95]), total cholesterol (TC)>6.22 mmol/L (8.8%, 1.58 [1.16, 2.15]), and Hemoglobin A1c (HbA1c) ≥6.00 mmol/L (7.7%, 1.69 [1.34, 2.14]), while it was significantly lower in non-diabetic subjects with diastolic blood pressure (DBP) between 80 to 89 mmHg (6.2%, 0.78 [0.64, 0.95]). These relationships remained significant even after controlling for multiple factors (WHR ≥0.9: multivariable-adjusted OR 1.39 [95% CI 1.07, 1.80]; TC>6.22 mmol/L: 1.56 [1.14, 2.12]; HbA1c ≥6.00 mmol/L: 1.64 [1.30, 2.08]; DBP 80-89 mmHg: 0.78 [0.64, 0.95]). However, no significant trend between depressive symptoms and WHC, TC, HbA1c, DBP was observed in diabetic women, and no significant trend relationship between depressive symptoms and BMI, WC, TG, or SBP was observed in both non-diabetic and diabetic women. Moreover, the prevalence of depressive symptoms was significantly higher in previously-diagnosed diabetes, compared with non-diabetic subjects, while no significant differences were observed between newly-diagnosed diabetes and non-diabetic subjects.

Conclusion

The present study showed a relationship between WHR, TC, HbA1c, DBP and depressive symptoms among non-diabetic women, while no significant relationship between them was observed among diabetic women, even after controlling for multiple confounding factors.     

Association between Serum Growth Hormone Levels and Nonalcoholic Fatty Liver Disease: A Cross-Sectional Study

Growth hormone (GH) is an important regulator of metabolism and body composition. GH deficiency is associated with increased visceral body fat and other features of the metabolic syndrome. Here we performed a cross-sectional study to explore the association of GH levels with nonalcoholic fatty liver disease (NAFLD), which is considered to be the hepatic manifestation of the metabolic syndrome. A total of 1,667 subjects were diagnosed as NAFLD according the diagnostic criteria, and 5,479 subjects were defined as the controls. The subjects with NAFLD had significantly lower levels of serum GH than the controls. Those with low GH levels had a higher prevalence of NAFLD and the metabolic syndrome. A stepwise logistic regression analysis showed that GH levels were significantly associated with the risk factor for NAFLD (OR = 0.651, 95%CI = 0.574–0.738, P<0.001). Our results showed a significant association between lower serum GH levels and NAFLD.     

Potential hormonal mechanisms of Attention-Deficit/Hyperactivity Disorder and Major Depressive Disorder: A new perspective

Hormonal influences on the organization of behavior are apparent to neuroendocrinologists but under-examined in relation to childhood and adolescent mental disorders. A central mystery in the field of developmental psychopathology is the preferential male vulnerability to behavior disorders in childhood and female vulnerability to emotional disorders in adolescence. Relative neglect of a hormonal explanation may be due to lack of simple or unifying conceptual paradigms to guide studies. This paper seeks to stimulate research in this area by drawing upon clinical psychology and neuroscience literatures to offer a heuristic paradigm for clinical research. Two syndromes are selected here for illustration: Attention-Deficit/Hyperactivity Disorder (ADHD) and Major Depressive Disorder (MDD), because they have opposite gender risk profiles. Two guiding theories are evaluated. First, prenatal organizational effects of testosterone may modulate striatally-based dopaminergic circuits in such a way as to place boys at greater risk for early developing inattention and disruptive behavioral disorders. Second, activational effects of estradiol at puberty may modulate amygdalar and other circuitry, with particular effects on serotonergic pathways, in such a way as to place girls at greater risk for internalizing and mood disorders. Hypotheses from these theories are evaluated based on the current available literature, and limitations of, and future directions for, this literature are discussed.     

Decreased Serum Levels of Mature Brain-Derived Neurotrophic Factor (BDNF), but Not Its Precursor proBDNF, in Patients with Major Depressive Disorder

Background

Meta-analyses have identified serum levels of brain-derived neurotrophic factor (BDNF) as a potential biomarker for major depressive disorder (MDD). However, at the time, commercially available human ELISA kits are unable to distinguish between proBDNF (precursor of BDNF) and mature BDNF because of limited BDNF antibody specificity. In this study, we examined whether serum levels of proBDNF, mature BDNF, and matrix metalloproteinase-9 (MMP-9), which converts proBDNF to mature BDNF, are altered in patients with MDD.

Methodology/Principal Findings

Sixty-nine patients with MDD and 78 age- and gender-matched healthy subjects were enrolled. Patients were evaluated using 17 items on the Structured Interview Guide for the Hamilton Depression Rating Scale. Cognitive impairment was evaluated using the CogState battery. Serum levels of proBDNF, mature BDNF, and MMP-9 were measured using ELISA kits. Serum levels of mature BDNF in patients with MDD were significantly lower than those of normal controls. In contrast, there was no difference in the serum levels of proBDNF and MMP-9 between patients and normal controls. While neither proBDNF nor mature BDNF serum levels was associated with clinical variables, there were significant correlations between MMP-9 serum levels and the severity of depression, quality of life scores, and social function scores in patients.

Conclusions/Significance

These findings suggest that mature BDNF may serve as a biomarker for MDD, and that MMP-9 may play a role in the pathophysiology of MDD. Further studies using larger sample sizes will be needed to investigate these results.     

Epidemiology of Major Depressive Disorder in Mainland China: A Systematic Review

Background

Major depressive disorder (MDD) is one of the important causes of disease burden in the general population. Given the experiencing rapid economic and social changes since the early 1990s and the internationally recognized diagnostic criteria and interview instruments across the surveys during 2001–2010 in china, the epidemiological studies on MDD got varied results. We performed this meta-analysis to investigate current, 12-month and lifetime prevalence rates of MDD in mainland China.

Methods

PubMed, Embase, Chinese Biological Medical Literature database (CBM), Chinese National Knowledge Infrastructure database (CNKI), and the Chinese Wanfang and Chongqing VIP database were searched for associated studies. We estimated the overall prevalence of MDD using meta-analysis.

Conclusions

Seventeen eligible studies were included. Our study showed that the overall estimation of current, 12-month and lifetime prevalence of MDD was 1.6, 2.3, 3.3%, respectively. The current prevalence was 2.0 and 1.7% in rural and urban areas, respectively; between female and male, it was 2.1 and 1.3%, respectively. In addition, the current prevalence of MDD diagnosed with SCID (Structured Clinical Interview for DSM-IV) was 1.8% and that diagnosed with CIDI (Composite International Diagnostic Interview) was 1.1%. In conclusion, our study revealed a relatively high prevalence rate in the lifetime prevalence of MDD. For current prevalence, MDD diagnosed with SCID had a higher prevalence rate than with CIDI; males showed a lower rate than females, rural residents seemed to have a greater risk of MDD than urban residents.     

Major Depressive Disorder and Stroke Risks: A 9-Year Follow-Up Population-Based,Matched Cohort Study

Background and Purpose

Major depressive disorder (MDD) is characterized by recurrent depressive episodes and one of the treatment choices is antidepressants. Patients with MDD are at greater risk of developing major metabolic diseases that may in turn lead to stroke. Moreover, both depressive symptoms and taking antidepressant medications are associated with higher risk of stroke. However, whether and how clinical depression increases stroke risk remains an unanswered question. Our aim was to provide answers to this question.

Methods

A matched cohort study of 5015 subjects (1003 MDD patients and 4012 control subjects) was conducted using a nationwide database. Subjects were followed to a maximum of 9 years to determine rates of newly-developed strokes, and controls and MDD groups with different levels of antidepressant refractoriness were compared to determine the temporal relation between stroke and three major metabolic comorbidities (i.e., diabetes mellitus, hypertension and hyperlipidemia). The levels of depressive symptoms and the antidepressant medications before stroke onset were investigated.

Results

Patients with MDD had significantly higher rates of stroke (4.3% vs. 2.8%, p<0.05) during the follow-up. Mediation regression analyses revealed that the occurrence of stroke in the MDD subjects was significantly mediated by the development of major metabolic diseases. Greater severity of depression, but not greater use of antidepressants, preceded the occurrence of stroke.

Conclusions

A clinical diagnosis of major depression leads to stroke indirectly through more intense depressive symptoms and the development of major comorbidities.     

Interhemispheric Functional Connectivity and Its Relationships with Clinical Characteristics in Major Depressive Disorder: A Resting State fMRI Study

Background

Abnormalities in large-scale, structural and functional brain connectivity have been increasingly reported in patients with major depressive disorder (MDD). However, MDD-related alterations in functional interaction between the cerebral hemispheres are still not well understood. Resting state fMRI, which reveals spontaneous neural fluctuations in blood oxygen level dependent signals, provides a means to detect interhemispheric functional coherence. We examined the resting state functional connectivity (RSFC) between the two hemispheres and its relationships with clinical characteristics in MDD patients using a recently proposed measurement named “voxel-mirrored homotopic connectivity (VMHC)”.

Methodology/Principal Findings

We compared the interhemispheric RSFC, computed using the VMHC approach, of seventeen first-episode drug-naive patients with MDD and seventeen healthy controls. Compared to the controls, MDD patients showed significant VMHC decreases in the medial orbitofrontal gyrus, parahippocampal gyrus, fusiform gyrus, and occipital regions including the middle occipital gyrus and cuneus. In MDD patients, a negative correlation was found between VMHC of the fusiform gyrus and illness duration. Moreover, there were several regions whose VMHC showed significant negative correlations with the severity of cognitive disturbance, including the prefrontal regions, such as middle and inferior frontal gyri, and two regions in the cereballar crus.

Conclusions/Significance

These findings suggest that the functional coordination between homotopic brain regions is impaired in MDD patients, thereby providing new evidence supporting the interhemispheric connectivity deficits of MDD. The significant correlations between the VMHC and clinical characteristics in MDD patients suggest potential clinical implication of VMHC measures for MDD. Interhemispheric RSFC may serve as a useful screening method for evaluating MDD where neural connectivity is implicated in the pathophysiology.     

Prevalence of Anxiety and Depressive Symptoms and Related Risk Factors among Physicians in China: A Cross-Sectional Study

Background

Physicians’ poor mental health not only hinders their professional performance and affects the quality of healthcare provided but also adversely affects patients’ health outcomes. Few studies in China have evaluated the mental health of physicians. The purposes of this study are to quantify Chinese physicians’ anxiety and depressive symptoms as well as evaluate associated risk factors.

Methods

In our study, 2641 physicians working in public hospitals in Shenzhen in southern China were recruited and interviewed by using a structured questionnaire along with validated scales testing anxiety and depressive symptoms. Multivariable logistic regression models were used to identify risk factors for anxiety and depressive symptoms.

Results

An estimated 25.67% of physicians had anxiety symptoms, 28.13% had depressive symptoms, and 19.01% had both anxiety and depressive symptoms. More than 10% of the participants often experienced workplace violence and 63.17% sometimes encountered it. Among our study population, anxiety and depressive symptoms were associated with poor self-reported physical health, frequent workplace violence, lengthy working hours (more than 60 hours a week), frequent night shifts (twice or more per week), and lack of regular physical exercise.

Conclusions

Our study demonstrates that anxiety and depressive symptoms are common among physicians in China, and the doctor-patient relationship issue is particularly stressful. Interventions implemented to minimize workload, improve doctor-patient relationships, and assist physicians in developing healthier lifestyles are essential to combat anxiety and depressive symptoms among physicians, which may improve their professional performance.     

The Efficacy of Neurofeedback in Patients with Major Depressive Disorder: An Open Labeled Prospective Study

The purpose of this study was to evaluate the effect of neurofeedback on depressive symptoms and electrophysiological disturbances in patients with major depressive disorder. We recruited participants suffering from depression to evaluate efficacy of left prefrontal beta with alpha/theta training. An 8-week, prospective, open-label study was undertaken. Twenty participants were recruited. The treatment protocol was twice or three times a week training of beta at F3 with alpha/theta at Pz for 8 weeks. When every visit, patients were received beta training for 30 min, and then alpha/theta training for 30 min. Baseline, 4 and 8 week scores of; the Hamilton rating scale for Depression (HAM-D), the Hamilton rating scale for Anxiety (HAM-A), the Beck Depression Inventory (BDI)-II, the Beck Anxiety Inventory (BAI), Clinical global impression-severity (CGI-S), and pre- and post-treatment resting state EEGs were compared. Interhemispheric alpha power asymmetry (A score) was computed for homologous sites F3–F4. Pre- and post-training clinical assessments revealed significant improvements in HAM–D, HAM-A, BDI, and CGI-S scores. Cumulative response rates by HAM-D were 35.0 and 75.0 % at 4 and 8 weeks, respectively, corresponding cumulative remission rates by HAM-D were 15.0 and 55.0 %, respectively. No significant differences were found between pre- and post-treatment A score. Neurofeedback treatment could improve depressive symptoms significantly. In addition, anxiety symptoms and clinical illness severity decreased significantly after neurofeedback treatment. Despite its several limitations, such as, small sample size and lack of a control group, this study suggested neurofeedback has significant effects in patients with major depressive disorder.     

Diurnal Profiles of Serum Triiodothyronine and Thyroxine Levels: A Study in Male Roseringed Parakeets (Psittacula krameri) Following Exogenous Administration of Melatonin

This study demonstrates that under subtropical environmental conditions the circulating levels of triiodothyronine (T 3 ) and thyroxine (T 4 ) in adult male roseringed parakeets undergo parallel changes according to a diurnal cycle with a trough in the early morning and a peak in the evening. Chronic afternoon administration of melatonin (25 µg/ 100 g body wt./ day for 30 consecutive days) abolishes time-bound changes in the concentrations of T 3 by suppressing its evening peak, but does not abolish the diurnal rhythm of T 4 . Exogenous melatonin, however, causes a significant increase in the evening value of serum T 4 and a decrease in its value at midnight resulting in phase-shifting of the diurnal fluctuations of T 4 compared to that in the control birds. It appears that exogenous melatonin can alter the diurnal profiles of serum thyroid hormones in a wild psittacine bird.     

Diurnal Profiles of Serum Triiodothyronine and Thyroxine Levels: A Study in Male Roseringed Parakeets (Psittacula krameri) Following Exogenous Administration of Melatonin

This study demonstrates that under subtropical environmental conditions the circulating levels of triiodothyronine (T 3) and thyroxine (T 4) in adult male roseringed parakeets undergo parallel changes according to a diurnal cycle with a trough in the early morning and a peak in the evening. Chronic afternoon administration of melatonin (25 µg/ 100 g body wt./ day for 30 consecutive days) abolishes time-bound changes in the concentrations of T 3 by suppressing its evening peak, but does not abolish the diurnal rhythm of T 4. Exogenous melatonin, however, causes a significant increase in the evening value of serum T 4 and a decrease in its value at midnight resulting in phase-shifting of the diurnal fluctuations of T 4 compared to that in the control birds. It appears that exogenous melatonin can alter the diurnal profiles of serum thyroid hormones in a wild psittacine bird.     

The Epidemiological Modelling of Major Depressive Disorder: Application for the Global Burden of Disease Study 2010

Background

Although the detrimental impact of major depressive disorder (MDD) at the individual level has been described, its global epidemiology remains unclear given limitations in the data. Here we present the modelled epidemiological profile of MDD dealing with heterogeneity in the data, enforcing internal consistency between epidemiological parameters and making estimates for world regions with no empirical data. These estimates were used to quantify the burden of MDD for the Global Burden of Disease Study 2010 (GBD 2010).

Method

Analyses drew on data from our existing literature review of the epidemiology of MDD. DisMod-MR, the latest version of the generic disease modelling system redesigned as a Bayesian meta-regression tool, derived prevalence by age, year and sex for 21 regions. Prior epidemiological knowledge, study- and country-level covariates adjusted sub-optimal raw data.

Results

There were over 298 million cases of MDD globally at any point in time in 2010, with the highest proportion of cases occurring between 25 and 34 years. Global point prevalence was very similar across time (4.4% (95% uncertainty: 4.2–4.7%) in 1990, 4.4% (4.1–4.7%) in 2005 and 2010), but higher in females (5.5% (5.0–6.0%) compared to males (3.2% (3.0–3.6%) in 2010. Regions in conflict had higher prevalence than those with no conflict. The annual incidence of an episode of MDD followed a similar age and regional pattern to prevalence but was about one and a half times higher, consistent with an average duration of 37.7 weeks.

Conclusion

We were able to integrate available data, including those from high quality surveys and sub-optimal studies, into a model adjusting for known methodological sources of heterogeneity. We were also able to estimate the epidemiology of MDD in regions with no available data. This informed GBD 2010 and the public health field, with a clearer understanding of the global distribution of MDD.     

STEP Levels Are Unchanged in Pre-Frontal Cortex and Associative Striatum in Post-Mortem Human Brain Samples from Subjects with Schizophrenia,Bipolar Disorder and Major Depressive Disorder

Increased protein levels of striatal-enriched tyrosine phosphatase (STEP) have recently been reported in postmortem schizophrenic cortex. The present study sought to replicate this finding in a separate cohort of postmortem samples and to extend observations to striatum, including subjects with bipolar disorder and major depressive disorder in the analysis. No statistically significant changes between disease and control subjects were found in STEP mRNA or protein levels in dorsolateral prefrontal cortex or associative striatum. Although samples were matched for several covariates, postmortem interval correlated negatively with STEP protein levels, emphasizing the importance of including these analyses in postmortem studies.     

Associations of Educational Attainment,Occupation, Social Class and Major Depressive Disorder among Han Chinese Women

Background

The prevalence of major depressive disorder (MDD) is higher in those with low levels of educational attainment, the unemployed and those with low social status. However the extent to which these factors cause MDD is unclear. Most of the available data comes from studies in developed countries, and these findings may not extrapolate to developing countries. Examining the relationship between MDD and socio economic status in China is likely to add to the debate because of the radical economic and social changes occurring in China over the last 30 years.

Principal findings

We report results from 3,639 Chinese women with recurrent MDD and 3,800 controls. Highly significant odds ratios (ORs) were observed between MDD and full time employment (OR = 0.36, 95% CI = 0.25–0.46, logP = 78), social status (OR = 0.83, 95% CI = 0.77–0.87, logP = 13.3) and education attainment (OR = 0.90, 95% CI = 0.86–0.90, logP = 6.8). We found a monotonic relationship between increasing age and increasing levels of educational attainment. Those with only primary school education have significantly more episodes of MDD (mean 6.5, P-value = 0.009) and have a clinically more severe disorder, while those with higher educational attainment are likely to manifest more comorbid anxiety disorders.

Conclusions

In China lower socioeconomic position is associated with increased rates of MDD, as it is elsewhere in the world. Significantly more episodes of MDD occur among those with lower educational attainment (rather than longer episodes of disease), consistent with the hypothesis that the lower socioeconomic position increases the likelihood of developing MDD. The phenomenology of MDD varies according to the degree of educational attainment: higher educational attainment not only appears to protect against MDD but alters its presentation, to a more anxious phenotype.