Nutritional and life style determinants of plasma homocysteine in schizophrenia patients

Prevalence and clinical demography of hyperhomocysteinemia in Han Chinese patients with schizophrenia

Previous studies have shown that high homocysteine worsens the occurrence, symptoms, and prognosis of patients with schizophrenia. The purpose of this study was to evaluate the prevalence, clinical correlation, and demographic characteristics of hyperhomocysteinemia in Han Chinese schizophrenia patients. In this study, we enrolled 330 schizophrenia patients and 190 healthy controls. Positive and Negative Syndrome Scale (PANSS) was used to evaluate the psychiatric symptoms of patients with schizophrenia. The plasma homocysteine level was measured by the enzyme cycle method and the concentration of homocysteine > 15 μmol/L was defined as hyperhomocysteinemia. The prevalence of hyperhomocysteinemia in Han Chinese schizophrenia patients and healthy controls was 55.05% and 26.98%, respectively. Schizophrenia patients with hyperhomocysteinemia had more male proportion, older age, higher smoking rate, lower HDL level, higher PANSS total score, and higher negative factor than those patients without hyperhomocysteinemia. Binary logical regression result showed that gender and age were the independent risk factors of hyperhomocysteinemia. Han Chinese patients with schizophrenia had high prevalence hyperhomocysteinemia than healthy controls, and elderly male patients have a higher risk of hyperhomocysteinemia. This study was registered in the China Clinical Trial Registration Center (chiCTR 1800017044).

Homocysteine levels in schizophrenia patients newly admitted to an acute psychiatric ward

OBJECTIVE

After the discovery of 'homocystinuria syndrome', many studies have suggested that high blood levels of homocysteine may be associated with schizophrenia. The aim of this study was to analyse the association between hyperhomocysteinaemia and schizophrenia.

METHODS

In a population of inpatients suffering from exacerbated schizophrenic disorders (N=100), we evaluated homocysteine levels the day after their admission to an acute psychiatric ward and compared it with that of a non-patient control group (N=110), matched for age and gender. We statistically analysed the correlation between homocysteine levels and selected variables: gender, age, years of illness and number of previous psychiatric admissions as well as Brief Psychiatric Rating Scale, Positive Negative Syndrome Scale and Global Assessment Functioning (GAF) Scores.

RESULTS

We observed elevated homocysteine levels (an increase of 7.84 µM on average per patient) in 32% of the patients, but we did not find any statistically significant difference between the homocysteine levels of our patients and controls. Hyperhomocysteinaemia presented a positive statistically significant correlation with years of illness (p<0.005) and a negative statistically significant correlation with GAF score (p<0.001), but not with other clinical variables.

CONCLUSIONS

Hyperhomocysteinaemia, which occurred in our schizophrenia patients with poor social and relational functioning after many years of illness, could represent an effect of altered lifestyle due to psychosis, but not a specific marker for schizophrenia.

Homocysteine as a potential biomarker in bipolar disorders: a critical review and suggestions for improved studies

INTRODUCTION

Homocysteine levels have been associated with major depression, but associations with bipolar disorder remain less clear. Some data suggest homocysteine levels have potential as a biomarker of treatment response; however the literature is mixed.

AREAS COVERED

Oxidized forms of homocysteine can be potentially neurotoxic leading to glutamate toxicity, apoptotic transformation and neurodegenerative processes. High homocysteine may be a risk biomarker for bipolar disorders, but the empirical base remains too weak for firm conclusions. This review discusses the current literature for homocysteine levels as a biomarker.

EXPERT OPINION

It is premature to foreclose the utility of homocysteine levels as a biomarker for bipolar disorder due the methodological inadequacies in the existing literature. These methodological design issues include lack of control for the confounding variables of concurrent medication, phase of bipolar disorder, gender, age, nutritional status, thyroid, liver and renal function, smoking or lean body mass. Well-powered association studies with confounder control could help shed more light on the important clinical question of homocysteine's utility as a biomarker in bipolar disorder. Future experiments are needed to examine the outcome of interventions modulating homocysteine for treating bipolar disorder. Only prospective randomized control trials will provide definitive evidence of the utility of homocysteine as a biomarker or therapeutic target.

Elevated homocysteine level in siblings of patients with schizophrenia

Increased homocysteine plasma levels were reported in patients with schizophrenia and Levine et al. (2002) suggested that such increase characterizes mainly males. In the following study we examined whether such increased levels also characterize male siblings of schizophrenia patients. Forty-four pairs of schizophrenia patients and their corresponding healthy male siblings were recruited and sampled for homocysteine. We also had age-matched controls for each of the sibling. The median homocysteine plasma level for patients was 13.0 µMol/L and 11.7 µMol/L for their male siblings compared with a median of 10.9 µMol/L for the siblings' controls. There was no significant difference between homocysteine plasma level in patients and their siblings. Significant difference was found for homocysteine plasma level between the siblings' group and their matched controls. A partial correlation of Ln plasma homocysteine level between patients and their siblings was found to be close to a zero correlation of -0.089, p=0.57 for the whole study group and -0.15, p=0.38 in the male-male patient-sibling pairs. Our results show that elevated homocysteine plasma level may characterize schizophrenia patients' male siblings, a finding that seems to agree with previous studies suggesting elevated homocysteine level as a risk factor for developing schizophrenia.

A systematic review of the nutritional status of women of a childbearing age with severe mental illness

Little is known about the nutritional status of pregnant women with severe mental illness. We therefore carried out a systematic review to investigate whether pregnant women and childbearing aged women with severe mental illness have significantly greater nutritional deficiencies compared with pregnant women and childbearing aged women with no mental illness. We carried out a search using MEDLINE, EMBASE and PsycINFO from January 1980 to January 2011 for studies on nutritional status of childbearing aged women with psychotic disorders. Identification of papers and quality rating of papers (using a modified version of the Newcastle-Ottawa scale) was carried out by two reviewers independently. We identified and screened 4,130 potentially relevant studies from the electronic databases. Fifteen studies met the inclusion criteria (n = 587 women). There were no studies of pregnant women. There was some evidence of low serum folate and vitamin B(12) levels and elevated homocysteine levels in childbearing aged women with psychotic disorders. Further research into the nutritional status of childbearing aged women with severe mental illness is needed. Maternal nutrition has a profound impact on foetal outcome, is a modifiable risk factor and therefore needs prioritising in the care of all childbearing aged women with severe mental illness.

One-carbon metabolism in psychiatric illness

The cost of psychiatric illness to the UK economy was recently estimated at pound77 billion annually. Despite years of research no firm aetiological explanation exists, and with no physiological or biochemical markers diagnosis is made entirely on a behavioural basis. All current pharmacological therapies are associated with serious long-term side effects. Substantial evidence supports the involvement of one-carbon cycle dysregulation in psychiatric illness, but this is not currently used as a basis for diagnosis or treatment. The present paper reviews the evidence for one-carbon cycle dysregulation in schizophrenic, bipolar, depressed and autistic patients. Also presented are novel findings from the field of epigenetics, which demonstrate how the one-carbon cycle-derived methyl donor S-adenosylmethionine influences the expression of key genes in the brain affecting memory, learning, cognition and behaviour, genes whose expression is reduced to varying degrees in these patient groups. Clinical evidence that nutritional supplements can rectify one-carbon cycle activity, and restore normal gene expression, suggests a novel approach to the development of biochemical tests and simple, non-harmful treatments for some psychiatric patients. Conversely, evidence from animal studies highlights the dangers of exposing the unborn fetus to very high dietary levels of folic acid, a one-carbon cycle cofactor. Fetal adaptations to a high-folate environment may interfere with folate metabolism postnatally, with serious consequences for the epigenetic regulation of gene expression. The public health implications of these diverse scenarios indicate an urgent need for further research in this field.

Homocysteine and cognition in first-episode psychosis patients

In the last years, there has been growing evidence linking elevated homocysteine levels with cognitive dysfunction in several neurological and neuropsychiatric diseases. The aim of the present study was to investigate the potential relationship between elevated homocysteine levels and cognitive deficits in first-episode psychosis patients. Plasma levels and cognitive performance of 139 patients and 99 healthy volunteers were compared. Patients were classified as elevated homocysteine (>90 percentile for controls) and normal and compared on 22 cognitive outcome measures grouped into cognitive domains known to be impaired in schizophrenia. Patients had a statistically significant increase in plasmatic homocysteine levels. In addition, they presented with significantly increased cognitive deficits. However, no relationship between homocysteine levels and cognitive impairment was detected. These results suggest the need for further studies to clarify the role of homocysteine in the etiology and prognosis of psychosis.

Reduced folic acid, vitamin B12 and docosahexaenoic acid and increased homocysteine and cortisol in never-medicated schizophrenia patients: implications for altered one-carbon metabolism

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 phospholipid 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.

One-carbon metabolism and schizophrenia: current challenges and future directions

Schizophrenia is a heterogeneous disease generally considered to result from a combination of heritable and environmental factors. Although its pathophysiology has not been fully determined, biological studies support the involvement of several possible components including altered DNA methylation, abnormal glutamatergic transmission, altered mitochondrial function, folate deficiency and high maternal homocysteine levels. Although these factors have been explored separately, they all involve one-carbon (C1) metabolism. Furthermore, C1 metabolism is well positioned to integrate gene-environment interactions by influencing epigenetic regulation. Here, we discuss the potential roles of C1 metabolism in the pathophysiology of schizophrenia. Understanding the contribution of these mechanisms could yield new therapeutic approaches aiming to counteract disease onset or progression.

Global leukocyte DNA methylation is not altered in euthymic bipolar patients

BACKGROUND

Bipolar disorder is a complex disorder hypothesized to involve an interaction of multiple susceptibility genes and environmental factors. The environmental factors may be mediated via epigenetic mechanisms such as DNA methylation. Since a different extent of DNA methylation has recently been reported in lymphoblastoid cells derived from monozygotic twins discordant for bipolar disorder, we hypothesized that bipolar patients exhibit a different extent of leukocyte global DNA methylation compared with healthy controls.

METHODS

DNA was extracted from peripheral blood leukocytes of 49 euthymic bipolar patients and 27 matched healthy controls. Percent of global genome DNA methylation was measured using the cytosine-extension method. Plasma homocysteine levels were measured by HPLC.

RESULTS

Leukocyte global DNA methylation did not differ between bipolar patients [62.3%+/-18.0 (S.D)] and control subjects (63.9%+/-14.6), p=0.70. Bipolar patients' plasma homocysteine levels (11.5 microM+/-4.8) did not differ from those of healthy controls (11.4+/-2.9), p=0.92.

LIMITATIONS

The assay we used, based on restriction by methylation-sensitive/insensitive enzymes followed by a radioactive DNA polymerase reaction was approved to accurately measure global DNA methylation, but has technical limitations i.e. restriction enzymes do not cleave all potential methylation sites in the genome and restriction sites may be altered by mutations or polymorphisms.

CONCLUSIONS

The lack of difference in leukocyte global DNA methylation between euthymic bipolar patients and healthy controls does not rule out the possibility that altered methylation of specific promoter regions is involved in the etiology of the disorder.

Homocysteine level in schizophrenia patients

OBJECTIVE

Elevated serum levels of homocysteine have been shown to be associated with schizophrenia in some studies, but the evidence is still limited and mixed. The aim of the present study was therefore to evaluate the serum homocysteine level in Chinese in schizophrenia patients and assess its association with clinical phenotypes of the disease.

METHOD

A total of 250 inpatients and 250 healthy controls were identified at Kowloon Hospital and the Red Cross Blood Donation Centre, respectively. Each subject was evaluated with a structured diagnostic interview. Demographic data were collected and blood was analysed for homocysteine level. The Positive and Negative Syndrome Scale was used to grade clinical symptoms of schizophrenia. Confounding factors affecting homocysteine levels were controlled by strict exclusion criteria or statistical methods.

RESULTS

Serum homocysteine level was elevated in Chinese schizophrenia patients. Both male (mean, 12.26 micromol L(-1); control, 11.40 micromol L(-1), p = 0.026) and female (mean, 9.61 micromol L(-1); control, 8.33 micromol L(-1), p < 0.001) patients had a higher serum homocysteine level than the healthy controls, and these differences persisted after controlling for age. There was no significant association between serum homocysteine level and duration of illness, clinical symptoms or age of onset of schizophrenia.

CONCLUSION

The serum homocysteine levels were elevated in both male and female Chinese schizophrenia patients. The levels were not apparently related to other clinical parameters.

Elevated serum homocysteine levels in male patients with PTSD

It has been suggested that an elevated serum or plasma homocysteine level may be a risk factor for neuropsychiatric conditions such as Alzheimer's disease, schizophrenia, and depression. Because depression is closely related to anxiety disorders, and because it has been suggested that stress may be associated with an elevated homocysteine level, we studied whether serum homocysteine levels are elevated in patients with posttraumatic stress disorder (PTSD). Total serum homocysteine levels in 28 male patients with PTSD were compared to those of 223 healthy controls. The effect of PTSD on the serum homocysteine level was significant (F=42.96, P<.0001). In a regression model for the PTSD patients, the duration of PTSD was found to predict serum homocysteine levels (t=2.228, P=.035). Our results suggest that elevated levels of homocysteine in male patients with PTSD may be related to pathophysiological aspects associated with the chronicity of this disorder.

Neuropsychological correlates of homocysteine levels in euthymic bipolar patients

BACKGROUND

We have previously reported that homocysteine levels are elevated in euthymic bipolar patients with functional deterioration. The current study was designed to extend this finding by examining the relationship between neuropsychological functioning and homocysteine levels in euthymic bipolar patients.

METHODS

Fifty-seven euthymic bipolar outpatients were assessed for serum levels of homocysteine, folic acid, and vitamin B-12 and administered a battery of neuropsychological tests.

RESULTS

We found that male bipolar subjects showed higher average homocysteine levels than a comparison group of normal subjects, that poorer functioning on a task of executive function (Wisconsin Card Sort) was related to higher homocysteine levels, and that folic acid or vitamin B-12 levels did not significantly affect neuropsychological functioning.

LIMITATIONS

These results, while suggesting some relationship between higher homocysteine levels, bipolar illness, and impairment in cognitive function do not establish any causative effects.

CONCLUSIONS

The findings of this study confirm that in euthymic bipolar patients, higher homocysteine levels are associated with poorer performance in some neuropsychological tests. Treatment trials will be required before it will be known if the putative decrements in the executive function of bipolar patients can be reversed, or at least retarded, if homocysteine levels are reduced (as, for example, by dietary addition of B vitamin supplements).

Associations of blood homocysteine concentrations in Arab schizophrenic patients

BACKGROUND

This study aimed to evaluate the blood homocysteine concentration in Arab patients with schizophrenia and assess its associations with clinical phenotypes of the disease.

SUBJECTS AND METHODS

Two age-matched groups of subjects were studied: (1) Healthy Controls, HC, n=165; (2) patients with schizophrenia, SZ: n=207. Each subject was evaluated with a standard questionnaire for age at disease onset, family history, disease severity and outcome. Plasma homocysteine levels (Hcys) were measured by immunoassay and serum levels of other biochemical parameters were measured by routine Autoanalyzer techniques.

RESULTS AND DISCUSSION

Group HC was heavier (body mass index, BMI) while SZ had greater waist-hip ratio (WHR) and plasma Hcys levels. In SZ, there were significant correlations between Hcys and BMI, triglycerides and HDL. Hcys levels in SZ were highest in the younger male patients.

CONCLUSION

Schizophrenic patients have increased blood Hcys levels which correlate with components of the metabolic syndrome. Hcys levels were highest in the younger male patients and were not influenced by prognostic features of the disease.

Plasma homocysteine, folate and B12 in chronic schizophrenia

Elevated plasma levels of the amino acid homocysteine have been associated with schizophrenia, particularly in young male patients. Among other factors, low folate and vitamin B12 levels have been implicated in the increase in homocysteine. In order to investigate this association, we determined plasma homocysteine, folate and B12 levels in 97 (67 males and 30 females) inpatients with chronic schizophrenia and 103 (46 males and 57 females) controls. Patients and controls did not differ in folate or B12 levels, after adjusting for age. Patients with schizophrenia had higher plasma homocysteine than controls (mean=15.42 micromol/l in cases versus 11.54 micromol/l in controls: F(1,195)=17.978; p<0.001). This difference persisted after controlling for folate and B12 concentrations. Both male and female patients had increased plasma homocysteine compared to controls [(males: mean=16.61 micromol/l in cases versus mean=13.72 in controls: F(1,110)=5.54; p=0.020) (females: mean=12.78 micromol/l in cases versus mean=9.79 micromol/l in controls: F(1,84)=13.54; p<0.001)]. When dividing our sample into two age groups (age < and > or =50 years), both young and older females and younger males with schizophrenia had increased plasma homocysteine compared to controls. We therefore suggest that homocysteinemia is a general risk factor for schizophrenia. We further suggest that it is not limited to young male patients and is not necessarily associated with low folate or B12 levels.

Homocysteine-reducing strategies improve symptoms in chronic schizophrenic patients with hyperhomocysteinemia

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.

Low essential fatty acid and B-vitamin status in a subgroup of patients with schizophrenia and its response to dietary supplementation

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.

High homocysteine serum levels in young male schizophrenia and bipolar patients and in an animal model

Elevated plasma homocysteine has been found to be a risk factor for Alzheimer's disease as well as cerebral vascular disease, suggesting that some risk factors can accelerate or increase the severity of several CNS disease processes. We screened plasma total homocysteine levels of 193 schizophrenic patients vs. 762 controls for plasma homocysteine levels. The effect of schizophrenia was marked (p<0.0001) and mean homocysteine level was 16.3+/-12 (S.D.) microM in schizophrenic patients vs. 10.6+/-3.6 (S.D.) microM in healthy controls. The increase was almost entirely in young male schizophrenic patients. It seemed important to determine if this finding is already present in newly admitted schizophrenic patients. Serum homocysteine levels were studied in 184 consecutively admitted schizophrenic patients and 305 control subjects. Homocysteine levels were markedly increased in this population of newly admitted schizophrenic patients, especially in young males. However, no difference was found for CSF homocysteine levels between schizophrenia patients and controls. We also examined homocysteine levels in 41 euthymic outpatients with bipolar disorder. Functional deterioration in patients was rated as 'present' or 'absent' by consensus of two treating clinicians. Young male bipolar patients were found to have higher homocysteine levels than controls. Among the male subjects, bipolar patients showing deterioration had homocysteine levels which were significantly higher than other patients. We attempted to develop a model of homocysteine neurotoxicity in mice. Mice were fed homocysteine in water at a dose of 200 mg/kg per mouse per day. Independent samples of animals were studied at 2 to 6 months with behavioral tests including apomorphine-induced stereotypy and spatial learning and memory in the Morris Water Maze. Homocysteine levels were elevated up to 800% at months 5 and 6 by this procedure. No homocysteine-induced defects were found in any behavioral test until month 5 when mild but statistically significant abnormalities in the Morris Water Maze were detected.