Feng LG, Song ZW, Xin F, Hu J. Association of plasma homocysteine and methylenetetrahydrofolate reductase C677T gene variant with schizophrenia: A Chinese Han population-based case-control study. Psychiatry Res. 2009 Aug 15;168(3):205-8.
This study examined the association of plasma homocysteine levels and the methylenetetrahydrofolate reductase (MTHFR) gene polymorphism with schizophrenia in the Han population residing in northern China. We detected the MTHFR C677T genotype in 123 schizophrenia patients and compared it with the genotype of 123 controls by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). In addition, by using the cyclophorase method, the plasma homocysteine concentration in 62 schizophrenia patients was determined and then compared with that in 62 controls; these 62 patients and 62 controls were a subset of the 123 patients and 123 controls. We found that the homocysteine levels in the patients were significantly higher than those in the controls. The frequency of homozygosity for the 677T allele of the MTHFR gene was higher in the patient group than in the control group, and the difference between the two groups was statistically significant for both the MTHFR genotype and the frequency of allele homozygosity. A significant difference was observed in the plasma homocysteine levels among the different genotypes in the patient and control groups. In conclusion, both elevated plasma homocysteine levels and variation in the MTHFR 677C–>T gene are related to increased rates of schizophrenia and are risk factors for schizophrenia.
Godfrey PS, Toone BK, Carney MW, Flynn TG, Bottiglieri T, Laundy M, Chanarin I, Reynolds EH. Enhancement of recovery from psychiatric illness by methylfolate. Lancet. 1990 Aug 18;336(8712):392-5.
41 (33%) of 123 patients with acute psychiatric disorders (DSM III diagnosis of major depression or schizophrenia) had borderline or definite folate deficiency (red-cell folate below 200 micrograms/l) and took part in a double-blind, placebo-controlled trial of methylfolate, 15 mg daily, for 6 months in addition to standard psychotropic treatment. Among both depressed and schizophrenic patients methylfolate significantly improved clinical and social recovery. The differences in outcome scores between methylfolate and placebo groups became greater with time. These findings add to the evidence implicating disturbances of methylation in the nervous system in the biology of some forms of mental illness.
Gu P, DeFina LF, Leonard D, John S, Weiner MF, Brown ES. Relationship between serum homocysteine levels and depressive symptoms: the Cooper Center Longitudinal Study. J Clin Psychiatry. 2012 May;73(5):691-5.
OBJECTIVE: Elevated serum levels of the amino acid homocysteine (HCY) are associated with a variety of diseases. To resolve conflicting findings in studies that suggest a relationship between elevated serum HCY levels and depression, we examined the relationship between HCY levels and depressive symptoms in the largest sample studied to date. METHOD: We conducted a cross-sectional study of 11,757 participants (68.9% men) aged 20 to 90 years who completed preventive health examinations at the Cooper Clinic, Dallas, Texas, from 2007 to 2010. Currently experiencing depression was defined as a 10-item Center for Epidemiologic Studies Depression Scale (CES-D) score of ≥ 10. Serum HCY levels were obtained. Data were analyzed in a multiple logistic regression model of CES-D score of ≥ 10. RESULTS: When controlling for age, sex, body mass index, exercise, education, smoking, antidepressant use, creatinine level, alcohol use, and chronic medical conditions, elevated HCY was associated with 26% greater odds of currently experiencing depressive symptoms (P = .007) as defined by CES-D score. CONCLUSIONS: In the largest sample examined to date, we found a significant positive relationship between elevated serum HCY levels and currently experiencing depressive symptoms. Given the cross-sectional nature of the study, it is not possible to determine the direction of the relationship or whether lowering HCY levels will ameliorate depressive symptoms. Thus, longitudinal studies are needed.
Hill M, Shannahan K, Jasinski S, Macklin EA, Raeke L, Roffman JL, Goff DC. Folate supplementation in schizophrenia: a possible role for MTHFR genotype. Schizophr Res. 2011 Apr;127(1-3):41-5.
BACKGROUND: Folate deficiency and the methylenetetrahydrofolate reductase (MTHFR) 677C>T polymorphism have been linked to negative symptoms in schizophrenia both independently and synergistically. This study examined the effect of folate supplementation on negative symptoms overall and in relation to MTHFR 677C>T genotype. METHOD: Forty-six stable adult schizophrenia outpatients were enrolled and 32 were randomised, double-blind, in a parallel-group, twelve week add-on trial of folate 2mg/d or matching placebo. The primary outcome measure was change from baseline to week 12 on the modified SANS total score using a mixed-model analysis. In addition, we measured the effect of MTHFR genotype on treatment effects and on changes in serum folate by grouping participants with T/T genotype together with C/T genotype and comparing their interactions to patients with C/C genotype. RESULTS: Twenty-eight participants completed the trial. Folate supplementation did not significantly affect negative symptoms compared to placebo across the entire cohort. However, there was a significant genotype×treatment effect on negative symptoms (F=7.13, df=1,39, p=0.01). In addition, MTHFR status significantly moderated the relationship between change in serum folate and change in negative symptoms: among participants with at least one copy of the T allele negative symptoms were more likely to improve with increased serum folate (p=0.03). CONCLUSION: We did not detect a therapeutic benefit of folate supplementation in a sample of patients with residual negative symptoms. However, a possible association between genotypes associated with reduced MTHFR activity and benefit from folate supplementation should be investigated further.
Kale A, Naphade N, Sapkale S, Kamaraju M, Pillai A, Joshi S, Mahadik S. Reduced folic acid, vitamin B12 and docosahexaenoic acid and increased homocysteine and cortisol in never-medicated schizophrenia patients: implications for altered one-carbon metabolism. Psychiatry Res. 2010 Jan 30;175(1-2):47-53.
Abnormal one-carbon metabolism has long been suggested as one of the mechanisms for neuropathology and psychopathology of schizophrenia. Variable levels of components of one-carbon metabolism (folic acid and vitamin B12) and consequent altered levels of homocysteine and phospho docosahexaenoic acid (DHA) have been independently reported, mostly in medicated patients. This study examined the simultaneous levels of these key components of one-carbon metabolism and its consequences in unique, medication-naïve first-episode psychotic patients (FEP, n=31) and healthy controls (HC, n=48) matched for confounds such as race, diet and lifestyle to reduce the variability. Significantly lower levels of folate and vitamin B12 in plasma and folate in red blood cells were observed in FEP compared to HC. These reductions paralleled the significant increase in plasma homocysteine and cortisol levels. Significantly reduced levels of membrane DHA were also observed in FEP compared to HC. This study, using a unique cohort, provided a broader mechanism (disturbed folic acid-vitamin B12-DHA balance) of altered one-carbon metabolism and one of its key consequential components, an increased homocysteine level that together with cortisol, can contribute to the neuropathology of psychosis. These data may have important implications for the amelioration of psychopathology in schizophrenia.
Kempisty B, Mostowska A, Górska I, Łuczak M, Czerski P, Szczepankiewicz A, Hauser J, Jagodziński PP. Association of 677C>T polymorphism of methylenetetrahydrofolate reductase (MTHFR) gene with bipolar disorder and schizophrenia. Neurosci Lett. 2006 Jun 12;400(3):267-71.
Methylenetetrahydrofolate reductase (MTHFR) gene polymorphism 677C>T has been shown to be a risk factor for psychiatric disorders. We investigated the genotype and allelic frequencies of MTHFR 677C>T polymorphism in the group of patients with bipolar disorder type I (BDI) (n=200) and schizophrenia (n=200), and in the control group (n=300). Odds ratio (OR) for patients with BD and schizophrenia with 677T allele was 1.988 ((95% CI=1.370-2.883); P=0.0003 (P=0.0006 after Bonferroni correction)) and 1.796 ((95% CI=1.237-2.609); P=0.0020 (P=0.0040 after Bonferroni correction)), respectively. The stratification of patients based on gender revealed significant association of 677T allele with male patients with BDI and schizophrenia (OR=2.393; 95% CI=1.429-4.006; P=0.0008 and OR=2.036; 95% CI=1.207-3.433; P=0.0073, respectively). This finding indicates possible association of BD and schizophrenia with the 1p36.3 MTHFR locus.
Kemperman RF, Veurink M, van der Wal T, Knegtering H, Bruggeman R, Fokkema MR, Kema IP, Korf J, Muskiet FA. Low essential fatty acid and B-vitamin status in a subgroup of patients with schizophrenia and its response to dietary supplementation. Prostaglandins Leukot Essent Fatty Acids. 2006 Feb;74(2):75-85.
We assessed essential fatty acid (EFA) and B-vitamin status, together with their determinants, in 61 patients with schizophrenia and established whether those with poor status responded biochemically to the appropriate dietary supplements. As a group, the patients had high erythrocyte saturated fatty acids (FAs), monounsaturated FA and low polyunsaturated FA of the omega3 and omega6 series. Patients reporting not to take vitamin supplements had low vitamin B12 and high homocysteine. Homocysteine variance proved best explained by folate in both the total group and male patients, and by vitamins B12 and B6 in females. Alcohol consumption and duration of illness are risk factors for low polyunsaturated FA status (< P2.5 of reference range), while male gender and absence of fish consumption predict hyperhomocysteinemia (> P97.5 of reference range). Two patients exhibited biochemical EFA deficiency and seven showed biochemical signs of omega3/docosahexaenoic acid (DHA) marginality. Four patients exhibited moderate hyperhomocysteinemia with plasma values ranging from 57.5 to 74.8 micromol/L. None of the five patients with either moderate hyperhomocysteinemia, biochemical EFA deficiency, or both, was predicted by their clinicians to have poor diets. That diet was nevertheless at the basis of these abnormalities became confirmed after supplementing 4 of them with B vitamins and with soybean and fish oils. We conclude that a subgroup of patients with schizophrenia has biochemical EFA deficiency, omega3/DHA marginality, moderate hyperhomocysteinemia, or combinations. Correction seems indicated in view of the possible relation of poor EFA and B-vitamin status with some of their psychiatric symptoms, but notably to reduce their high risk of cardiovascular disease.
Levine J, Stahl Z, Sela BA, Ruderman V, Shumaico O, Babushkin I, Osher Y, Bersudsky Y, Belmaker RH. Homocysteine-reducing strategies improve symptoms in chronic schizophrenic patients with hyperhomocysteinemia. Biol Psychiatry. 2006 Aug 1;60(3):265-9.
BACKGROUND: An elevated homocysteine level is reported to be a risk factor for several diseases, including Alzheimer’s and cerebrovascular disease. Recently, several studies have reported that homocysteine levels are elevated in many schizophrenic patients. Homocysteine levels can be lowered by oral folic acid, B-12, and pyridoxine. METHODS: Forty-two schizophrenic patients with plasma homocysteine levels >15 micromol/L were treated with these vitamins for 3 months and placebo for 3 months in a study with a randomized, double-blind, placebo-controlled, crossover design. RESULTS: Homocysteine levels declined with vitamin therapy compared with placebo in all patients except for one noncompliant subject. Clinical symptoms of schizophrenia as measured by the Positive and Negative Syndrome Scale declined significantly with active treatment compared with placebo. Neuropsychological test results overall, and Wisconsin Card Sort (Categories Completed) test results in particular, were significantly better after vitamin treatment than after placebo. CONCLUSIONS: A subgroup of schizophrenic patients with hyperhomocysteinemia might benefit from the simple addition of B vitamins.
Maron BA, Loscalzo J. The treatment of hyperhomocysteinemia. Annu Rev Med. 2009;60:39-54.
The unique biochemical profile of homocysteine is characterized by chemical reactivity supporting a wide range of molecular effects and by a tendency to promote oxidant stress-induced cellular toxicity. Numerous epidemiological reports have established hyperhomocysteinemia as an independent risk factor for cardiovascular disease, cerebrovascular disease, dementia-type disorders, and osteoporosis-associated fractures. Although combined folic acid and B-vitamin therapy substantially reduces homocysteine levels, results from randomized placebo-controlled clinical trials testing the effect of vitamin therapy on outcome in these diseases have generally fallen short of expectations. These results have led some to abandon homocysteine monitoring in the management of patients with cardiovascular or cognitive disorders. These trials, however, have generally included patients with only mildly elevated homocysteine levels and have not addressed several clinical scenarios in which homocysteine reduction may be effective, including the primary prevention of atherothrombotic disease in individuals at low or intermediate risk, or those with severe hyperhomocysteinemia.
Muntjewerff JW, Hoogendoorn ML, Aukes MF, Kahn RS, Sinke RJ, Blom HJ, den Heijer M. No evidence for a preferential transmission of the methylenetetrahydrofolate reductase 677T allele in families with schizophrenia offspring. Am J Med Genet B Neuropsychiatr Genet. 2007 Oct 5;144B(7):891-4.
The methylenetetrahydrofolate reductase (MTHFR) 677C > T polymorphism has been associated with an increased risk of schizophrenia in various case-control studies. However, case-control studies are sensitive to population stratification, which is not an issue in family-based studies. We conducted a family-based study comprising 120 families with a schizophrenic family member to explore the association between the parental MTHFR 677C > T polymorphism and schizophrenia risk in offspring. In addition, a meta-analysis was performed using the available studies with data on this subject. Transmission Disequilibrium Test (TDT) analysis showed no preferential transmission of the 677T allele from parents heterozygous for the MTHFR 677C > T polymorphism to schizophrenia offspring (P = 0.27). The genotype relative risks were 1.43 (95% CI: 0.83-2.47) for the 677TT and 1.42 (95% CI: 0.54-3.78) for the 677CT genotype, relative to the 677CC genotype. A meta-analysis using data from family-based studies comprising a total of 416 parent-child triads yielded no evidence implicating the 677T allele in schizophrenia risk (P = 0.58). By applying a log-linear model, we found no asymmetry within parental mating type. Our data provided no evidence that transmission of the MTHFR 677T allele is associated with schizophrenia risk. In addition, we found no evidence that the maternal genotype influences the risk of having schizophrenia offspring substantially.
Muntjewerff JW, Kahn RS, Blom HJ, den Heijer M. Homocysteine, methylenetetrahydrofolate reductase and risk of schizophrenia: a meta-analysis. Mol Psychiatry. 2006 Feb;11(2):143-9.
Elevated plasma homocysteine concentration has been suggested as a risk factor for schizophrenia, but the results of epidemiological studies have been inconsistent. The most extensively studied genetic variant in the homocysteine metabolism is the 677C>T polymorphism in the methylenetetrahydrofolate reductase (MTHFR) gene, resulting in reduced enzyme activity and, subsequently, in elevated homocysteine. A meta-analysis of eight retrospective studies (812 cases and 2113 control subjects) was carried out to examine the association between homocysteine and schizophrenia. In addition, a meta-analysis of 10 studies (2265 cases and 2721 control subjects) on the homozygous (TT) genotype of the MTHFR 677C>T polymorphism was carried out to assess if this association is causal. A 5 micromol/l higher homocysteine level was associated with a 70% (95% confidence interval, CI: 27-129) higher risk of schizophrenia. The TT genotype was associated with a 36% (95% CI: 7-72) higher risk of schizophrenia compared to the CC genotype. The performed meta-analyses showed no evidence of publication bias or excessive influence attributable to any given study. In conclusion, our study provides evidence for an association of homocysteine with schizophrenia. The elevated risk of schizophrenia associated with the homozygous genotype of the MTHFR 677C>T polymorphism provides support for causality between a disturbed homocysteine metabolism and risk of schizophrenia.
Roffman JL, Weiss AP, Purcell S, Caffalette CA, Freudenreich O, Henderson DC, Bottiglieri T, Wong DH, Halsted CH, Goff DC. Contribution of methylenetetrahydrofolate reductase (MTHFR) polymorphisms to negative symptoms in schizophrenia. Biol Psychiatry. 2008 Jan 1;63(1):42-8.
BACKGROUND: Folate deficiency may contribute to negative symptoms in schizophrenia, but the underlying mechanism remains uncertain. We examined whether the methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C functional polymorphisms contribute to negative symptoms. METHODS: outpatients with schizophrenia (n = 200) were evaluated with the Positive and Negative Syndrome Scale (PANSS). Subjects also provided a blood sample for MTHFR genotype and serum chemistries. Comparisons of PANSS symptoms, folate, and homocysteine status were conducted based on genotype. RESULTS: The 677T allele load was associated with negative symptom severity. Contrary to our expectations, the T allele was also found to be protective against positive symptoms. The A1298C polymorphism did not contribute to negative symptoms, and only weakly to positive symptoms. The specific effects of the C677T polymorphism were confirmed with haplotype analysis. Among patients homozygous for the 667T allele, serum folate levels correlated with negative symptom severity. CONCLUSIONS: Increased MTHFR 677T allele load confers risk for negative symptoms in schizophrenia, while reducing severity of positive symptoms. Further, the biochemical interaction of low serum folate with 677T-variant MTHFR may induce downstream effects salient to the expression of negative symptoms.
Roffman JL, Brohawn DG, Nitenson AZ, Macklin EA, Smoller JW, Goff DC. Genetic Variation Throughout the Folate Metabolic Pathway Influences Negative Symptom Severity in Schizophrenia. Schizophr Bull. 2011 Oct 20.
Low serum folate levels previously have been associated with negative symptom risk in schizophrenia, as has the hypofunctional 677C>T variant of the MTHFR gene. This study examined whether other missense polymorphisms in folate-regulating enzymes, in concert with MTHFR, influence negative symptoms in schizophrenia, and whether total risk allele load interacts with serum folate status to further stratify negative symptom risk. Medicated outpatients with schizophrenia (n = 219), all of European origin and some included in a previous report, were rated with the Positive and Negative Syndrome Scale. A subset of 82 patients also underwent nonfasting serum folate testing. Patients were genotyped for the MTHFR 677C>T (rs1801133), MTHFR 1298A>C (rs1801131), MTR 2756A>G (rs1805087), MTRR 203A>G (rs1801394), FOLH1 484T>C (rs202676), RFC 80A>G (rs1051266), and COMT 675G>A (rs4680) polymorphisms. All genotypes were entered into a linear regression model to determine significant predictors of negative symptoms, and risk scores were calculated based on total risk allele dose. Four variants, MTHFR 677T, MTR 2756A, FOLH1 484C, and COMT 675A, emerged as significant independent predictors of negative symptom severity, accounting for significantly greater variance in negative symptoms than MTHFR 677C>T alone. Total allele dose across the 4 variants predicted negative symptom severity only among patients with low folate levels. These findings indicate that multiple genetic variants within the folate metabolic pathway contribute to negative symptoms of schizophrenia. A relationship between folate level and negative symptom severity among patients with greater genetic vulnerability is biologically plausible and suggests the utility of folate supplementation in these patients.
Rozen, R., 1997. Genetic predisposition to hyperhomocysteinemia:deficiency of methylenetetrahydrofolate reductase. Thrombosis and Haemostasis 78, 523–526.
Vares M, Saetre P, Deng H, Cai G, Liu X, Hansen T, Rasmussen HB, Werge T, Melle I, Djurovic S, Andreassen OA, Agartz I, Hall H, Terenius L, Jönsson EG. Association between methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism and age of onset in schizophrenia. Am J Med Genet B Neuropsychiatr Genet. 2010 Mar 5;153B(2):610-8.
Different lines of evidence indicate that methylenetetrahydrofolate reductase (MTHFR) functional gene polymorphisms, causative in aberrant folate-homocysteine metabolism, are associated with increased vulnerability to several heritable developmental disorders. Opposing views are expressed considering the possible association between MTHFR and susceptibility for schizophrenia. In order to evaluate if age of onset could explain some of this discrepancy we investigated the relationship between two functional MTHFR gene polymorphisms and age at onset in this disorder. Scandinavian patients (n = 820) diagnosed with schizophrenia, schizoaffective disorder, and schizophreniform disorder were investigated. Two functional MTHFR single nucleotide polymorphisms (SNPs; rs1801131 and rs1801133) were genotyped and the effect of MTHFR polymorphisms on the age of onset was examined with survival analysis. In an attempt to replicate the findings from the Scandinavian sample, the association between rs1801133 and age at onset was also analyzed in Chinese high-risk families, with two or more affected siblings (n = 243). Among the Scandinavian patients the functional MTHFR SNP rs1801133 (C677T) significantly affected age at onset of schizophrenia in a dose-dependent manner (P = 0.0015), with lower age of onset with increasing numbers of the mutant T-allele. There was no evidence of rs1801131 (A1298C) affecting age of onset in schizophrenia. Within the Chinese high-risk families carriers of the MTHFR 677T allele showed earlier age at onset than siblings being homozygous for the wild-type allele (P = 0.008). The MTHFR C677T polymorphism may play a role as a modifying factor for age of onset in schizophrenia.
Yoshimi A, Aleksic B, Kawamura Y, Takahashi N, Yamada S, Usui H, Saito S, Ito Y, Iwata N, Inada T, Noda Y, Yamada K, Ozaki N. Gene-wide association study between the methylenetetrahydrofolate reductase gene (MTHFR) and schizophrenia in the Japanese population, with an updated meta-analysis on currently available data. Schizophr Res. 2010 Dec;124(1-3):216-22.
Methylenetetrahydrofolate reductase (MTHFR) is a critical molecule for single-carbon transfer reactions. Recent evidence suggests that polymorphisms of MTHFR are related to neural tube deficits and the pathogenesis of schizophrenia. While several studies have demonstrated associations between the gene encoding the MTHFR (MTHFR) polymorphisms and schizophrenia, these studies lack consistency. Therefore, we conducted a gene-wide association study (patients with schizophrenia = 696, control subjects = 747) and performed imputation analysis. Additionally, we performed meta-analysis on currently available data from 18 studies for two common functional polymorphisms (rs1801131 and rs1801133). There were no significant associations with schizophrenia in the single marker analysis for the seven tagging SNPs of MTHFR. In the haplotypic analysis, a nominally significant association was observed between the haplotypes, which included four SNPs (rs1801133, rs17421511, rs17037396, and rs9651118) and the schizophrenic patients. Additionally, the imputation analysis demonstrated there were several associated markers on the MTHFR chromosomal region. However, confirmatory analyses of three tagging SNPs (rs1801133, rs17037396, and rs9651118) and the top SNP (rs17421511) for the imputation results (patients with schizophrenia = 797, control subjects = 1025) failed to replicate the haplotypic analysis and the imputation results. These findings suggest that MTHFR polymorphisms are unlikely to be related to the development of schizophrenia in the Japanese population. However, since our meta-analysis results demonstrated strong support for association of rs1801133 with schizophrenia, further replication studies based on a gene-wide approach need to be considered.
Zhang C, Xie B, Du Y, Cheng W, Fang Y, Yu S. Further evidence that methylenetetrahydrofolate reductase A1298C polymorphism is a risk factor for schizophrenia. J Neural Transm. 2010 Sep;117(9):1115-7.
Previous work suggests that the methylenetetrahydrofolate reductase gene (MTHFR) functional polymorphism A1298C may be a risk factor for schizophrenia. In this study, the genetic association between the MTHFR A1298C polymorphism and schizophrenia was investigated in 379 patients with schizophrenia and 380 age- and sex-matched controls subjects. The results showed an association between the 1298C allele and the disorder (OR 1.39, 95% confidence interval 1.08-1.79). This provides further evidence that the MTHFR A1298C polymorphism may play a role in conferring risk for schizophrenia in the Chinese Han population.