The MTHFR C677T polymorphism is associated with depressive episodes in patients from Northern Ireland

Biomarkers in Child and Adolescent Depression

Despite the significant prevalence of Major Depressive Disorder in the pediatric population, the pathophysiology of this condition remains unclear, and the treatment outcomes poor. Investigating tools that might aid in diagnosing and treating early-onset depression seems essential in improving the prognosis of the future disease course. Recent studies have focused on searching for biomarkers that constitute biochemical indicators of MDD susceptibility, diagnosis, or treatment outcome. In comparison to increasing evidence of possible biomarkers in adult depression, the studies investigating this subject in the youth population are lacking. This narrative review aims to summarize research on molecular and biochemical biomarkers in child and adolescent depression in order to advocate future directions in the research on this subject. More studies on depression involving the youth population seem vital to comprehend the natural course of the disease and identify features that may underlie commonly observed differences in treatment outcomes between adults and children.

Association between variants of MTHFR genes and psychiatric disorders: A meta-analysis

Background

Psychiatric disorders have seriously affected human life, one of the risk genes related to psychosis is the methylenetetrahydrofolatereductase (MTHFR) gene. This gene has a potential role in psychiatric disorders. Therefore, a meta-analysis is conducted to investigate the correlations between two prevalent MTHFR single nucleotide polymorphisms (SNPs), MTHFR C677T, A1298C, severe psychological disorders (schizophrenia, major depression, bipolar disorder).

Methods

A total of 81 published studies were screened and selected by a search of electronic databases up to April 2022. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the association between MTHFR polymorphism and psychiatric disorders susceptibility by using random effect models.

Results

We found that MTHFR C677T polymorphism is significantly related to schizophrenia and major depression in the overall population. MTHFR C677T has been linked to an increased risk of bipolar disorder in the recessive model (TT vs. CT + CC). Ethnic subgroup analysis shows that schizophrenia and major depression significantly correlate with MTHFR C677T and A1298C in Asian populations but not Caucasians. Besides, schizophrenia is correlated substantially with MTHFR C677T in the African population. However, the MTHFR A1298C polymorphism is only marginally linked to major depression.

Conclusion

Findings of the current study revealed that MTHFR may contribute to the common pathogenesis of psychiatric diseases and that its variants may be essential in controlling the expression of psychosis-related genes. This study could help the researchers and health specialists in the early diagnosis and treatment of psychiatric disorders.

The association between serum homocysteine and depression: A systematic review and meta-analysis of observational studies

BACKGROUND

Hyperhomocysteinaemia is known to interfere with neurological functions; however, there is a controversy regarding the relationship between homocysteine and depression.

MATERIALS AND METHODS

Science Direct, MEDLINE and ISI Web of Science were searched to find relevant articles, published up to August 2020. Studies were included if they compared homocysteine levels in healthy subjects with subjects with depression. Also, articles that reported the association between hyperhomocysteinaemia and risk of depression were included. Odds ratios of depression and means of homocysteine were used to ascertain the overall effect size.

RESULTS

Homocysteine level was higher in subjects with depression in comparison with healthy controls (weight mean difference = 2.53 µmol/L, 95% confidence interval: 1.77, 3.30), and the depression diagnostic tool was a source of heterogeneity. Homocysteine level was significantly higher in subjects with depression in studies that used Diagnostic and Statistical Manual of Mental Disorders-IV (DSM-IV), Geriatric Depression Scale (GDS), Zung Self-Rating Depression Scale (ZDRS) and Beck Depression Index II (BDI-II) as depression diagnostic tools. Also, participants with hyperhomocysteinaemia had a higher chance of depression (Pooled risk = 1.34, 95% confidence interval: 1.19, 1.52), where the depression diagnostic tool was a source of heterogeneity. In contrast to ZDRS and Patient Health Questionnaire (PHQ) subgroups, hyperhomocysteinaemia yielded a significantly higher risk of depression in DSM-IV, GDS and 'other' subgroups.

CONCLUSION

Homocysteinemia level is higher in individuals with depression. However, the depression diagnostic tool used is instrumental in influencing their association, and thus, future studies should focus on the tools for depression assessment.

Impact of Supplementation and Nutritional Interventions on Pathogenic Processes of Mood Disorders: A Review of the Evidence

This narrative review was conducted using searches of the PubMed/Medline and Google Scholar databases from inception to November 2019. Clinical trials and relevant articles were identified by cross-referencing major depressive disorder (and/or variants) with the following terms: folate, homocysteine, S-adenosylmethionine (SAMe), L-acetylcarnitine, alpha-lipoic acid, N-acetylcysteine, L-tryptophan, zinc, magnesium, vitamin D, omega-3 fatty acids, coenzyme Q10, and inositol. Manual reviews of references were also performed using article reference lists. Abnormal levels of folate, homocysteine, and SAMe have been shown to be associated with a higher risk of depression. Numerous studies have demonstrated antidepressant activity with L-methylfolate and SAMe supplementation in individuals with depression. Additionally, the amino acids L-acetylcarnitine, alpha-lipoic acid, N-acetylcysteine, and L-tryptophan have been implicated in the development of depression and shown to exert antidepressant effects. Other agents with evidence for improving depressive symptoms include zinc, magnesium, omega-3 fatty acids, and coenzyme Q10. Potential biases and differences in study designs within and amongst the studies and reviews selected may confound results. Augmentation of antidepressant medications with various supplements targeting nutritional and physiological factors can potentiate antidepressant effects. Medical foods, particularly L-methylfolate, and other supplements may play a role in managing depression in patients with inadequate response to antidepressant therapies.

Methylenetetrahydrofolate reductase and psychiatric diseases

Methylenetetrahydrofolate reductase (MTHFR) is a key enzyme for the critical process of one-carbon metabolism involving folate and homocysteine metabolisms. It is known that some polymorphism of MTHFR would result in reduction of MTHFR enzyme activity as well as DNA methylation process, later shown to have significant impacts in various psychiatric diseases. However, it is unclear whether the polymorphism of MTHFR could be an independent or an add-on risk factor for specific psychiatric symptoms, such as anxiety, depression, positive, or negative symptoms of schizophrenia, or acts as risk factor for specific psychiatric disorders, such as schizophrenia, major depression, autisms, and bipolar disorders. It is also understudied on whether folate supplements could be an effective treatment for psychiatric patients with defect MTHFR activity. In this review, we not only gathered the most recent discoveries on MTHFR polymorphism and related DNA methylation in various psychiatric disorders, but also highlighted the potential relationships between MTHFR activity and implication of folate-related function in specific mental diseases.

Maternal and infant genetic variants, maternal periconceptional use of selective serotonin reuptake inhibitors, and risk of congenital heart defects in offspring: population based study

Objective To evaluate whether the association between maternal periconceptional use of selective serotonin reuptake inhibitors (SSRIs) and increased risk of congenital heart defects in offspring is modified by maternal or infant genetic variants in folate, homocysteine, or transsulfuration pathways.Design Population based study. DNA from mothers, fathers, and infants was genotyped with an Illumina GoldenGate custom single nucleotide polymorphism panel. A hybrid design based on a log linear model was used to calculate relative risks and Bayesian false discovery probabilities (BFDP) to identify polymorphisms associated with congenital heart defects modified by SSRI use.Data sources Data from the US National Birth Defects Prevention Study on 1180 liveborn infants with congenital heart defects and 1644 controls, born 1997-2008.Main outcome measures Cases included infants with selected congenital heart defects and control infants had no major defects. SSRI use was obtained from telephone interviews with mothers.Results For women who reported taking SSRIs periconceptionally, maternal SHMT1 (rs9909104) GG and AGgenotypes were associated with a 5.9 and 2.4 increased risk of select congenital heart defects in offspring, respectively, versus the AA genotype (BFDP=0.69). Compared with the AA genotype, BHMT (rs492842 and rs542852) GG and AG genotypes were associated with twice the riskof congenital heart defects (BFDP=0.74 and 0.79, respectively). MGST1 (rs2075237) CC and ACgenotypes were associated with an increased risk compared with the GG genotype (8.0 and 2.8, respectively; BFDP=0.79). Single nucleotide polymorphism in infant genes in the folate (MTHFS rs12438477), homocysteine (TRDMT1 rs6602178 and GNMT rs11752813) and transsulfuration (GSTP1 rs7941395 and MGST1 rs7294985) pathways were also associated with an increased risk of congenital heart defects.Conclusions Common maternal or infant genetic variants in folate, homocysteine, or transsulfuration pathways are associated with an increased risk of certain congenital heart defects among children of women taking SSRIs during cardiogenesis.

Genetic epidemiology of migraine and depression

Background

Migraine and major depressive disorder (commonly referred to as depression) are both common disorders with a significant impact on society. Studies in both clinical and community-based settings have demonstrated a strong relationship between migraine and depression. In addition to complicating the diagnosis, depression that is comorbid with migraine may lower treatment adherence, increase risk of medication overuse and is associated with migraine chronification, thus leading to higher direct and indirect costs and poorer health-related outcomes with increased disability.

Aim

The aim of this review is to summarise the current knowledge on the genetic epidemiology of migraine and depression and the possible biological mechanisms underlying their comorbidity.

Methods

We present a narrative review reporting on the current literature.

Results and conclusions

Epidemiological findings indicate that there is a bidirectional relationship between migraine and depression, with one disorder increasing the risk for the other and vice versa, suggesting shared biological mechanisms. Twin and family studies indicate that this bidirectional relationship can be explained, at least partly, by shared underlying genetically determined disease mechanisms. Although no genes have been robustly associated with the aetiology of both migraine and depression, genes from serotonergic, dopaminergic and GABAergic systems together with variants in the MTHFR and BDNF genes remain strong candidates.

Soybeans or Soybean Products Consumption and Depressive Symptoms in Older Residents in Rural Northeast China: A Cross-Sectional Study

OBJECTIVE

Depression is one of the most common mental disorders among elderly subjects. The purpose of this study is to estimate the prevalence of depressive symptoms and the association between soybeans consumption and depressive symptoms among older residents in rural Northeast China.

DESIGN

Cross-sectional study.

SETTING

A representative sample of the rural Northeast residents.

PARTICIPANTS

This survey was conducted from July 2012 to August 2013 which randomly selected and examined a total of 1717 residents aged ≥ 65 years from the rural Northeast China.

MEASUREMENTS

All participants completed the Patient Health Questionnaire-9 (PHQ-9). Information on demographic and lifestyle characteristics and blood biochemical indexes were collected by well-trained personnel.

RESULTS

The prevalence of depressive symptoms in the elderly was 8.9%. Women had significantly higher prevalence of depressive symptoms than men (13.3% vs.4.6%, P<0.001). Individuals consuming soybeans ≥4times/week had statically lower possibility to have depressive symptoms than those rarely consuming (3.6%vs. 12.5%, P<0.05). In addition to some conventional risk factors like sex, annual income, educational status, current smoking and chronic diseases status were associated with depressive symptoms, proper sleep duration (7-8h/d) [OR(95%CI):0.28(0.15,0.53)] and frequently consumption of soybeans or soybean products [OR (95%CI): 0.36 (0.15,0.87) for 2-3times/week and OR (95%CI):0.50 (0.34,0.74) for ≥4times/week] significantly decreased the risk of depressive symptoms among elderly in rural Northeast China.

CONCLUSION

Women had significantly higher prevalence of depressive symptoms than men in rural China. Individuals who rarely consume soybeans or soybean products are more likely to suffer depressive symptoms. Rural elderly residents should be cautiously screened to prevent or treat depression.

The MAOA, COMT, MTHFR and ESR1 gene polymorphisms are associated with the risk of depression in menopausal women

OBJECTIVE

The aim of the study was assessment of a possible relationship between the polymorphisms of the candidate genes participating in the etiology of some neurological and psychiatric disorders and the risk of depression in perimenopausal and postmenopausal women.

METHODS

A total of 167 (54 perimenopausal and 113 postmenopausal) Caucasian women from western Poland, aged 42-67, were recruited as the patient group in the study because of depressive symptoms, and another 321 healthy women (102 perimenopausal and 219 postmenopausal) served as the controls. All study participants were evaluated for climacteric and depressive disorders according to the Kupperman index and Hamilton rating scale for depression (HRSD), respectively. The following candidate genes were selected for the study: 5HTR2A, 5HTR1B, 5HTR2C, TPH1, TPH2, MAOA, COMT, NET, GABRB1, ESR1, MTHFR, MTR and MTHFD1. In each group the frequencies of the polymorphisms were determined using PCR-RFLP analysis.

RESULTS

After correcting for Bonferroni multiple tests, we found associations between the MAOA c.1460C>T (SNP 1137070), COMT c.472G>A (SNP 4680), MTHFR c.677C>T (SNP 1801133) and ESR1 454(-351) A>G (SNP 9340799) polymorphisms to mild and moderate depressive symptoms in menopausal women. In the perimenopausal and postmenopausal women, genotype association of the MAOA c.1460 CT and c.1460 CT+TT (OR=1.83; pcorr=0.009 and OR=1.85; pcorr=0.003, resp.), and of the MTHFR c.677 TT and c.677 CT+TT (OR=3.52; pcorr=0.00009 and OR=2.06; pcorr=0.0006, resp.), as well as of the COMT c.472 GA and COMT c.472 GA+AA genotypes (OR=2.23; pcorr=0.03 and OR=2.17; pcorr=0.027, resp.) in the postmenopausal women revealed significantly higher frequencies of these variants in depressed female patients than in controls, whereas the ESR1 454(-351) AG and 454(-351) AG+GG genotypes were associated with lower risk of depression in postmenopausal women (OR=0.48; pcorr=0.012, and OR=0.52; pcorr=0.015, resp.).

CONCLUSIONS

Our study substantiates the involvement of the MAOA and MTHFR polymorphisms in climacteric depression and offers evidence that the COMT and ESR1 genes may also play a role in the susceptibility to depressive mood in postmenopausal women.

Hyperhomocysteinemia is a result, rather than a cause, of depression under chronic stress

Background

Although the accumulation of homocysteine (Hcy) has been implicated in the pathogenesis of depression, whether Hcy is directly involved and acts as the primary cause of depressive symptoms remains unclear. The present study was designed to clarify whether increased Hcy plays an important role in stress-induced depression.

Results

We employed the chronic unpredictable mild stress model (CUMS) of depression for 8 weeks to observe changes in the plasma Hcy level in the development of depression. The results showed that Wistar rats exposed to a series of mild, unpredictable stressors for 4 weeks displayed depression-like symptoms such as anhedonia (decreased sucrose preferences) and a decreased 5-Hydroxy Tryptophan (5-HT) concentration in the hippocampus. At the end of 8 weeks, the plasma Hcy level increased in the CUMS rats. The anti-depressant sertraline could decrease the plasma Hcy level and improve the depression-like symptoms in the CUMS rats. RhBHMT, an Hcy metabolic enzyme, could decrease the plasma Hcy level significantly, although it could not improve the depressive symptoms in the CUMS rats.

Conclusions

The results obtained from the experiments did not support the hypothesis that the increased Hcy concentration mediated the provocation of depression in CUMS rats, and the findings suggested that the increased Hcy concentration in the plasma might be the result of stress-induced depression.

The one-carbon-cycle and methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism in recurrent major depressive disorder; influence of antidepressant use and depressive state?

BACKGROUND

An important biological factor suggested in the pathophysiology of (recurrent) Major Depressive Disorder (MDD) concerns a polymorphism in a gene encoding for the MTHFR-enzyme of the one-carbon (1-C)-metabolism. Integratively investigating key 1-C-components (folate, homocysteine, vitamin B6 and B12), including the possible effects of antidepressant medication and depressive state, could provide more insight in the possible association between the MTHFR-polymorphism and recurrent MDD.

METHODS

We compared the MTHFR C677T-polymorphism together with the key 1-C-components in clinically ascertained patients with recurrent MDD (n=137) to age- and gender-matched healthy controls (n=73).

RESULTS

First, patients had lower folate (t=2.25; p=.025) as compared to controls; a difference that resolved after correction for demographics (t=1.22; p=.223). Second, patients that were depressed during sampling had lower vitamin B6 (t=-2.070; p=.038) and higher homocysteine (t=2.404; p=.016) compared to those in remission. Finally, current use of antidepressants had no influence on the 1-C-components.

CONCLUSIONS

Despite investigation of a specific recurrently depressed patient population, we found no clear associations with the 1-C-cycle, except for higher homocysteine and lower vitamin B6 during the depressed state. This suggests that 1-C-cycle alterations in MDD are state-associated, possibly resulting from high levels of acute (psychological) stress, and may provide a treatment target to reduce cardiovascular risk in this population.

Methylenetetrahydrofolate reductase (MTHFR) genetic variation and major depressive disorder prognosis: A five-year prospective cohort study of primary care attendees

Methylenetetrahydrofolate reductase (MTHFR) genetic variation has been associated with the diagnosis of major depressive disorder (MDD) but no study to date has examined the effect MTHFR variation has on MDD prognosis. We sought to examine the prospective effects of two common MTHFR variants (C677T and A1298C) as well as seven haplotype-tagging single nucleotide polymorphisms (htSNPs) on MDD prognosis over a 5-year (60-month) period. Participants were 147 depressed primary care attendees enrolled in the Diagnosis, Management and Outcomes of Depression in Primary Care (diamond) prospective cohort study. Prognosis of MDD was measured using three methods: (1) DSM-IV criteria, (2) Primary Care Evaluation of Mental Disorders Patient Health Questionnaire-9 (PHQ-9), and (3) Center for Epidemiologic Studies Depression Scale (CESD). DSM-IV criteria for MDD was assessed using the Composite International Diagnostic Interview at baseline and 24, 36, 48, and 60 months post-baseline; whereas, PHQ-9 and CESD measures were employed at baseline and 12, 24, 36, 48, and 60 months post-baseline. Repeated measures analysis of variance showed that PHQ-9 symptom severity trajectories differed by C677T genotype (F = 3.34, df = 2,144, P = 0.038), with 677CC genotype showing the most severe symptom severity course over the 60 months of observation. Neither the A1298C polymorphism nor any of the htSNPs were associated with MDD prognosis regardless of measure used. Our results suggest that the MTHFR C677T polymorphism may serve as a marker for MDD prognosis pending independent replication.

One-carbon metabolism and bipolar disorder

OBJECTIVE

Folate is one of the most widely used nutraceuticals for the treatment of mood disorders. In this article, we review folate metabolism, its relationship with bipolar disorder, and its therapeutic potential.

METHODS

We searched PubMed and the Cochrane Library for relevant articles up to and including the year 2012. Background information, proposed mechanisms of action, and results from clinical trials were reviewed.

RESULTS

Folate is an essential cofactor involved in methylation reactions, which are critical for monoamine synthesis and homocysteine regulation. Folate level is thought to be associated with mood disorders and limited response to antidepressants. Functional deficiency, due to a common genetic variant of the methylenetetrahydrofolate reductase (NAD(P)H) (MTHFR) gene, could also affect the presentation of bipolar disorder. Sodium valproate and lamotrigine, commonly used mood stabilizers for the treatment of bipolar disorder, can potentially interfere with folate and homocysteine metabolism. Previous studies consistently support the efficacy of folate in the treatment of depression; one study showed efficacy in the treatment of mania. Biologically active forms of folate formulations, which do not require biochemical conversion, could be beneficial in the treatment of bipolar disorder.

CONCLUSIONS

Folate augmentation could be effective for the treatment of bipolar disorder. A common genetic variant of the MTHFR gene might impact the treatment effect of folate augmentation. The biologically active form of folate could potentially correct mood stabilizer-associated functional folate deficiency, help normalize monoamine synthesis, and improve outcomes.

Association between MTHFR C677T polymorphism and depression: An updated meta-analysis of 26 studies

BACKGROUND

Previous studies concerning the association between the 5,10-methylenetetrahydrofolate reductase (MTHFR) C677T gene polymorphism and depression have provided inconclusive findings. A meta-analysis was therefore performed to investigate a more reliable estimate.

METHODS

This meta-analysis recruited 26 published studies which were selected by a search of electronic databases up to January 2013, including 4992 depression cases and 17,082 controls. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the association between MTHFR C677T polymorphism and depression susceptibility using random effect models.

RESULTS

Meta-analyses results suggested that MTHFR C677T polymorphism contributed to the increased depression risk in overall populations (for T vs. C: OR=1.19, 95%CI=1.07-1.32; for TT+CT vs. CC: OR=1.15, 95%CI=1.01-1.31; for TT vs. CC: OR=1.42, 95%CI=1.16-1.75; for TT vs. CT+CC: OR=1.38, 95%CI=1.16-1.63). Subgroup analysis by ethnicity indicated an association in Asian populations (for T vs. C: OR=1.36, 95%CI=1.11-1.66; for TT+CT vs. CC: OR=1.32, 95%CI=1.03-1.69; for TT vs. CC: OR=1.88, 95%CI=1.26-2.79; for TT vs. CT+CC: OR=1.76, 95%CI=1.30-2.38); and a marginal association in White populations (for TT vs. CT+CC: OR=1.15, 95%CI=1.01-1.31). However, the association between the MTHFR C677T polymorphism and depression was not observed in the elderly.

CONCLUSION

The MTHFR C677T polymorphism was associated with an increased risk of depression, especially in Asian populations. However, there was no evidence indicating a correlation in the elderly.

Folate metabolism genes, dietary folate and response to antidepressant medications in late-life depression

OBJECTIVE

The primary aims of this study were to (i) determine whether folate metabolism genetic polymorphisms predict age of onset and occurrence of late life depression; and (ii) determine whether folate metabolism genetic polymorphisms predict response to antidepressant medications in late-life depression.

METHODS

This study used the Conte Center for the Neuroscience of Depression and the Neurocognitive Outcomes of Depression in the Elderly Study database, which includes individuals aged ≥60. The folate nutrition assessment was determined by the Block Food Frequency Questionnaire. Genotype was evaluated for 15 single nucleotide polymorphisms from 10 folate metabolism genes. Logistic regression models were used to examine genetic polymorphisms and folate estimates with association with depression age of onset and remission status.

RESULTS

There were 304 Caucasians in the database, 106 of these were not depressed and 198 had a diagnosis of depression. There were no significant differences between remitters and non-remitters in age, sex or estimated folate intakes. There were no folate estimates or folate metabolism gene single nucleotide polymorphisms that significantly predicted age of onset of depression or occurrence of depression. Methionine synthase reductase (MTRR) A66G (rs1801394) was significantly associated with remission status (p = 0.0077) such that those with the AA genotype were 3.2 times as likely as those with the GG genotype to be in remission (p = 0.0020). Methylenetetrahydrofolate reductase A1298C (rs1801131) achieved a borderline significance for association with remission status (p = 0.0313).

CONCLUSION

The major finding from this study is that the MTRR A66G genotype predicts response to selective serotonin reuptake inhibitor antidepressants in late life depression.

Assessing Effects of l-Methylfolate in Depression Management: Results of a Real-World Patient Experience Trial

OBJECTIVE

l-Methylfolate has been shown in retrospective and prospective studies to enhance antidepressant response. The aim of this study was to prospectively assess change in depression severity and medication satisfaction in patients prescribed l-methylfolate within a naturalistic setting.

METHOD

Between November 2010 and April 2012, patients who reported being treated for major depressive disorder rated their experiences before and after 3 months on the prescription medical food l-methylfolate (Deplin) 7.5 mg or 15 mg, through an automated telephone system. Survey questions included the 9-item Patient Health Questionnaire (PHQ-9), as well as quality of life and medication satisfaction questions. The primary outcome was change in depression severity from baseline to endpoint.

RESULTS

Of 554 patients, 502 reported that l-methylfolate was added to their existing antidepressant and 52 were treated with l-methylfolate alone, without an antidepressant. Enrolled participants reported a mean reduction of 8.5 points (58.2% decrease) in their PHQ-9 score (mean baseline PHQ-9 score = 14.6, mean follow-up PHQ-9 score = 6.1; P = .000); 376 (67.9%) responded to treatment (50% reduction in baseline PHQ-9 score) and 253 (45.7%) achieved remission (follow-up PHQ-9 score < 5) after an average of 95 days of therapy. In addition, patients achieved significant reductions in self-reported impairment in their work/home/social life (P = .000). Medication satisfaction with l-methylfolate (mean satisfaction score = 7.0) was significantly higher than with prior medication (mean satisfaction score = 5.2; P = .000).

CONCLUSIONS

RESULTS show that in a naturalistic setting, patients managed with l-methylfolate achieved statistically significant improvements in self-reported depression symptoms and functioning and greater satisfaction with their medication treatment.

Folates and S-adenosylmethionine for major depressive disorder

Interest in nonpharmaceutical supplements for treating major depressive disorder (MDD) has increased significantly, both among patients and among clinicians during the past decades. Despite the large array of antidepressants (ADs) available, many patients continue to experience relatively modest response and remission rates, in addition to a burden of side effects that can hinder treatment compliance and acceptability. In this article, we review the literature on folates and S-adenosylmethionine (SAMe), 2 natural compounds linked in the 1-carbon cycle metabolic pathway, for which substantial evidence supports their involvement in mood disorders. Background information, efficacy data, proposed mechanisms of action, and side effects are reviewed. Based on existing data, supplementation with SAMe, as well as with various formulations of folates, appears to be efficacious and well tolerated in reducing depressive symptoms. Compared with other forms of folates, 5-methyltetrahydrofolate (L-methylfolate or 5-MTHF) may represent a preferable treatment option for MDD given its greater bioavailability in patients with a genetic polymorphism, and the lower risk of specific side effects associated with folic acid. Although further randomized controlled trials in this area appear warranted, SAMe and L-methylfolate may represent a useful addition to the AD armamentarium.

Prevalence of MTHFR C677T and MS A2756G polymorphisms in major depressive disorder, and their impact on response to fluoxetine treatment

OBJECTIVE

To examine the prevalence of the C677T polymorphism of the methylene tetrahydrofolate reductase (MTHFR) gene and the A2756G polymorphism of methionine synthase (MS), and their impact on antidepressant response.

METHODS

We screened 224 subjects (52% female, mean age 39 ± 11 years) with SCID-diagnosed major depressive disorder (MDD), and obtained 194 genetic samples. 49 subjects (49% female, mean age 36 ± 11 years) participated in a 12-week open clinical trial of fluoxetine 20-60 mg/day. Association between clinical response and C677T and A2756G polymorphisms, folate, B12, and homocysteine was examined.

RESULTS

Prevalence of the C677T and A2756G polymorphisms was consistent with previous reports (C/C = 41%, C/T = 47%, T/T = 11%, A/A = 66%, A/G = 29%, G/G = 4%). In the fluoxetine-treated subsample (n = 49), intent-to-treat (ITT) response rates were 47% for C/C subjects and 46% for pooled C/T and T/T subjects (nonsignificant). ITT response rates were 38% for A/A subjects and 60% for A/G subjects (nonsignificant), with no subjects exhibiting the G/G homozygote. Mean baseline plasma B12 was significantly lower in A/G subjects compared to A/A, but folate and homocysteine levels were not affected by genetic status. Plasma folate was negatively associated with treatment response.

CONCLUSION

The C677T and A2756G polymorphisms did not significantly affect antidepressant response. These preliminary findings require replication in larger samples.

Meta-analysis of MTHFR gene variants in schizophrenia, bipolar disorder and unipolar depressive disorder: evidence for a common genetic vulnerability?

Past analyses examining the relationship between genetic variation in the 5, 10-methylenetetrahydrofolate reductase (MTHFR) gene and psychiatric disorders have provided mixed and largely inconclusive findings. MTHFR is involved in the one-carbon metabolic pathway which is essential for DNA biosynthesis and the epigenetic process of DNA methylation. We conducted a meta-analysis of all published case-control studies investigating associations between two common MTHFR single nucleotide polymorphisms (SNPs), MTHFR C677T (sample size 29,502) and A1298C (sample size 7934), and the major psychiatric disorders (i) schizophrenia (SZ), (ii) bipolar disorder (BPD), and (iii) unipolar depressive disorder (UDD). In order to examine possible shared genetic vulnerability, we also tested for associations between MTHFR and all of these major psychiatric disorders (SZ, BPD and UDD) combined. MTHFR C677T was significantly associated with all of the combined psychiatric disorders (SZ, BPD and UDD); random effects odds ratio (OR)=1.26 for TT versus CC genotype carriers; confidence interval (CI) 1.09-1.46); meta-regression did not suggest moderating effects of psychiatric diagnosis, sex, ethnic group or year of publication. Although MTHFR A1298C was not significantly associated with the combination of major psychiatric disorders, nor with SZ, there was evidence for diagnostic moderation indicating a significant association with BPD (random effects OR=2.03 for AA versus CC genotype carriers, CI: 1.07-3.86). Meta-analysis on UDD was not possible due to the small number of studies available. This study provides evidence for shared genetic vulnerability for SZ, BPD and UDD mediated by MTHFR 677TT genotype, which is in line with epigenetic involvement in the pathophysiology of these psychiatric disorders.

Genetic variation in folate metabolism is not associated with cognitive functioning or mood in healthy adults

The present study examined the associations between genetic variation in folate metabolism on the one hand and cognitive functioning and mood on the other in healthy individuals. Two independent population-based samples were used, including 777 participants, aged 24-82 years, from the Maastricht Aging Study (MAAS); and 818 participants, aged 50-70 years, from the Folic Acid and Carotid Intima-Media Thickness (FACIT) study. Thymidylate synthase (TS) 2R→3R and serine hydroxymethyltransferase (SHMT1) 1420C→T polymorphisms were determined in both populations. In addition, the 5,10-methylenetetrahydrofolate reductase (MTHFR) 677C→T polymorphism was determined in the MAAS population. Cognitive performance was assessed in both populations using a neuropsychological test battery. In the MAAS population only, cognitive performance was retested after 12years of follow-up (n=612), and mood was measured at baseline (n=772) and 12-year follow-up (n=565) by means of the depression subscale of the Symptom Checklist 90. We found that in both study populations, cognitive performance was not associated with TS 2R→3R or SHMT1 1420C→T polymorphisms at baseline, after correction for age, sex, and level of education. The MTHFR 677C→T polymorphism was not associated with cognitive performance in the MAAS population. None of the polymorphisms in the MAAS population were related to mood at baseline or over 12 years. In conclusion, our findings do not support the involvement of genetic variation in folate metabolism in cognitive performance or mood in healthy individuals.

Methylenetetrahydrofolate reductase gene variant (MTHFR C677T) and migraine: a case control study and meta-analysis

Background

Migraine is a common disorder that often coexists with depression. While a functional polymorphism in methyleneterahydrofolate reductase gene (MTHFR C677T) has been implicated in depression; the evidence to support an association of MTHFR with migraine has been inconclusive. We aim to investigate the effect of this variant on propensity for migraine and to perform a systematic review and meta-analysis of studies of MTHFR and migraine to date.

Methods

Individuals with migraine (n = 447) were selected from the Depression Case Control (DeCC) study to investigate the association between migraine and MTHFR C677T single nucleotide polymorphism (SNP) rs1801133 using an additive model compared to non-migraineurs adjusting for depression status. A meta-analysis was performed and included 15 studies of MTHFR and migraine.

Results

MTHFR C677T polymorphism was associated with migraine with aura (MA) (OR 1.31, 95% CI 1.01-1.70, p = 0.039) that remained significant after adjusting for age, sex and depression status. A meta-analysis of 15 case-control studies showed that T allele homozygosity is significantly associated with MA (OR = 1.42; 95% CI, 1.10-1.82) and total migraine (OR = 1.37; 95% CI, 1.07-1.76), but not migraine without aura (OR = 1.16; 95% CI, 0.36-3.76). In studies of non-Caucasian population, the TT genotype was associated with total migraine (OR= 3.46; 95% CI, 1.22-9.82), whereas in studies of Caucasians this variant was associated with MA only (OR = 1.28; 95% CI, 1.002-1.63).

Conclusions

MTHFR C677T is associated with MA in individuals selected for depression study. A meta-analysis of 15 studies supports this association and demonstrated effects across ethnic groups.

The folate hydrolase 1561C>T polymorphism is associated with depressive symptoms in Puerto Rican adults

OBJECTIVE

To examine the associations between variants of genes involved in the uptake, retention, and metabolism of folate and depressive symptoms and to analyze whether such associations are direct or through mediation by folate or homocysteine.

METHODS

We performed a cross-sectional analysis of data from 976 Puerto Rican adults, aged 45 to 75 years, residing in the greater Boston area, Massachusetts. Twelve single nucleotide polymorphisms (SNPs) in genes involved in folate uptake, retention, and metabolism were investigated. These include FOLH1 (folate hydrolase), FPGS (folate polyglutamate synthase), GGH (γ-glutamyl hydrolase), MTHFR (methylenetetrahydrofolate reductase), MTR (methionine synthase), PCFT (proton-coupled folate transporter), and RFC1 (reduced folate carrier 1). The Center for Epidemiologic Studies Depression Scale (CES-D) was used to measure depressive symptoms.

RESULTS

The FOLH1 rs61886492 C>T (or 1561C>T) polymorphism was significantly associated with lower CES-D score (p = .0025) after adjusting for age, sex, population admixture, smoking, and educational attainment. Individuals with the TT and TC genotypes were 49% less likely (odds ratio = 0.51, 95% confidence interval = 0.29-0.89) to report mild depressive symptoms (CES-D score ≥16 and ≤26) and 64% less likely (odds ratio = 0.36, 95% confidence interval = 0.18-0.69) to report moderate to severe depressive symptoms (CES-D score >26), compared with those with the CC genotype. No significant mediation effects by plasma folate or homocysteine on the associations between this single nucleotide polymorphism and CES-D score were observed.

CONCLUSIONS

The FOLH1 1561C>T polymorphism may be associated with the risk of depressive symptoms.

Chronic variable stress induces oxidative stress and decreases butyrylcholinesterase activity in blood of rats

Depressive disorders, including major depression, are serious and disabling, whose mechanisms are not clearly understood. Since life stressors contribute in some fashion to depression, chronic variable stress (CVS) has been used as an animal model of depression. In the present study we evaluated some parameters of oxidative stress [thiobarbituric acid reactive substances (TBARS), catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx)], and inflammatory markers (interleukin 6, C reactive protein, tumor necrosis factor-alpha and nitrites), as well as the activity of butyrylcholinesterase in blood of rats subjected to chronic stress. Homocysteine and folate levels also were measured. Stressed animals were submitted to different mild stressors for 40 days. After CVS, a reduction in weight gain was observed in the stressed group, as well as an increase in immobility time in the forced swimming test as compared with controls. Stressed animals presented a significant increase on TBARS and SOD/CAT ratio, but stress did not alter GPx activity and any inflammatory parameters studied. CVS caused a significant inhibition on serum butyrylcholinesterase activity. Stressed rats had higher plasmatic levels of homocysteine without differences in folate levels. Although it is difficult to extrapolate our findings to the human condition, the alterations observed in this work may be useful to help to understand, at least in part, the pathophysiology of depressive disorders.

Nutrition and late-life depression: etiological considerations

Depression is a debilitating mental disorder that frequently occurs in older adults, especially in those with vascular diseases. Nutritional factors have the potential to decrease the occurrence of late-life depression but have not been adequately studied. Low folate levels, disturbed omega-3 fatty acid metabolism and obesity have been associated with depression, and may be causal factors. Longitudinal studies are urgently needed in order to examine the potential of dietary factors to prevent late-life depression.

Polymorphic variants of genes encoding MTHFR, MTR, and MTHFD1 and the risk of depression in postmenopausal women in Poland

OBJECTIVE

Disturbances in the folate-dependent one-carbon metabolism have been reported in depression. Polymorphic variants of genes encoding key enzymes of folate and methionine metabolism may have an impact on catecholamine catabolism conducted by catechol-O-methyltransferase.

METHODS

The distribution of polymorphisms of genes encoding methylenetetrahydrofolate reductase (MTHFR); methionine synthase (MTR); 5,10-methylenetetrahydrofolate dehydrogenase, 5,10-methenyltetrahydrofolate cyclohydrolase and 10-formyltetrahydrofolate synthetase (MTHFD1) was examined in postmenopausal women with (n=83) and without depression (n=89).

RESULTS

We found a significant contribution of the MTHFR 677C>T polymorphic variants to depression in postmenopausal women. Odds ratio (OR) for women with depression and MTHFR TT genotype was 3.478 (95% CI=1.377-8.783), P=0.0096 and OR of the TT and CT genotypes was 2.345 (95% CI=1.258-4.373), P=0.0086. Moreover, after stratification based on depression severity in postmenopausal women, we found that the MTHFR TT genotype displayed a 4.831-fold increased risk of moderate and severe depression (95% CI=1.975-11.820, P=0.0008). We did not observe statistical differences in the distribution of MTR 2756A>G and MTHFD1 1958G>A polymorphic variants in groups of postmenopausal women with and without depression. However, the MTR GG genotype exhibited a 5.750-fold increased risk of moderate and severe depression in postmenopausal women (95% CI=1.547-21.379, P=0.013).

CONCLUSIONS

Our findings indicate a significant role of folate and possible methionine metabolism involvement in the development of depression in postmenopausal women.

Increased plasma homocysteine levels in patients with multiple sclerosis and depression

BACKGROUND

The aim of the study was to assess the plasma levels of homocysteine in patients with multiple sclerosis (MS) and to investigate whether an association with depression exists.

METHODS

Plasma homocysteine (Hcy), vitamin B12 and plasma folate were measured in 65 moderately disabled patients with relapsing/remitting MS (RR-MS) and 60 healthy controls. All subjects were assessed with the Beck Depression Inventory (BDI).

RESULTS

Hcy levels were significantly increased in MS patients compared to controls (13.5 +/- 4.7 mumol/l vs 8.5 +/- 3.1, p < 0.001). A significant correlation was found between Hcy levels and BDI scores (Pearson r = 0.3025, p < 0.05). Plasma Hcy was not related to Extended Disability Status Scale (EDSS) score, age, disease duration or vitamin B12 and folate.

CONCLUSION

Moderately disabled MS patients with elevated Hcy levels are particularly prone to develop depressive symptomatology. Further study is warranted in order to elucidate the prognostic and therapeutic implications of this novel finding.

No association with the 5,10-methylenetetrahydrofolate reductase gene and major depressive disorder: results of the depression case control (DeCC) study and a meta-analysis

Unipolar major depressive disorder (MDD) is a complex disorder thought to result from multiple genes in combination with environmental and developmental components. The 5,10-methylenetetrahydrofolate reductase gene (MTHFR) has been implicated in MDD in a meta-analysis of association studies and is within a linkage region suggested by a recent study of affected sib pairs. A single base mutation in the MTHFR gene (C677T) results in the production of a mildly dysfunctional thermolabile enzyme. The MTHFR 677TT genotype, and to a lesser extent the 677CT genotype, is associated with a significant elevation in the circulating concentrations of homocysteine and a decrease in serum folate concentrations. This may parallel a similar reduction in 5-methyltetrahydrofolate in the CNS, leading to a potential reduction in monoamine neurotransmitter function and an elevated risk of depressive disorder. To test the hypothesis that the MTHFR C677T polymorphism is involved in the predisposition to MDD, we conducted an association study of 1,222 patients with recurrent MDD and 835 control subjects. This allows 99% power to detect an effect of the size reported in the study of Bjelland et al. 2003, however no significant differences in genotype or allele frequencies between depressive patients and controls were observed. This was the case in the sample as a whole, and when females and males were considered separately. Our findings suggest that the MTHFR C677T polymorphism is not involved in the etiology of clinically significant recurrent MDD.

Is low folate a risk factor for depression? A meta-analysis and exploration of heterogeneity

Low folate has been causatively linked to depression, but research is contradictory. An association may arise due to chance, bias, confounding or reverse causality. A systematic review of observational studies which examined the association between depression and folate was conducted. 11 relevant studies (15 315 participants; three case-control studies, seven population surveys and one cohort study) examining the risk of depression in the presence of low folate were found. Pooling showed a significant relationship between folate status and depression (odds ratio (OR)(pooled unadjusted) = 1.55; 95% CI 1.26 to 1.91). This relationship remained after adjustment for potential confounding (OR)(pooled adjusted) = 1.42; 95% CI 1.10 to 1.83). Folate levels were also lower in depression. There is accumulating evidence that low folate status is associated with depression. Much of this evidence comes from case-control and cross-sectional studies. Cohort studies and definitive randomised-controlled trials to test the therapeutic benefit of folate are required to confirm or refute a causal relationship.

Folic acid and the treatment of depression

Reduced plasma, serum, or red blood cell folate is commonly found in major depressive illnesses. Supplementing antidepressant medication with folic acid enhances the therapeutic effect. Although more work is required to confirm these beneficial results, it is suggested that, meanwhile, 2 mg of folic acid should be given during the acute, continuation, and maintenance treatment of depression.