The Role of Methyl Donors of the Methionine Cycle in Gastrointestinal Infection and Inflammation

Vitamin deficiency is well known to contribute to disease development in both humans and other animals. Nonetheless, truly understanding the role of vitamins in human biology requires more than identifying their deficiencies. Discerning the mechanisms by which vitamins participate in health is necessary to assess risk factors, diagnostics, and treatment options for deficiency in a clinical setting. For researchers, the absence of a vitamin may be used as a tool to understand the importance of the metabolic pathways in which it participates. This review aims to explore the current understanding of the complex relationship between the methyl donating vitamins folate and cobalamin (B12), the universal methyl donor S-adenosyl-L-methionine (SAM), and inflammatory processes in human disease. First, it outlines the process of single-carbon metabolism in the generation of first methionine and subsequently SAM. Following this, established relationships between folate, B12, and SAM in varying bodily tissues are discussed, with special attention given to their effects on gut inflammation.

Associations between vitamin E, oxidative stress markers, total homocysteine levels, and physical activity or cognitive capacity in older adults

This study examined the associations between vitamin E, oxidative stress markers, total homocysteine levels, and physical activity or cognitive capacity in older adults. One hundred and six older adults (62 men, 44 women) within the age range of 56-81 years participated. The Global Physical Activity Questionnaire and the Loewenstein Occupational Therapy Cognitive Assessment were used to assess physical activity and cognitive function, respectively. Vitamin E (e.g., α-tocopherol and γ-tocopherol), oxidative stress markers (e.g., total antioxidant capacity and nitric oxide), and total homocysteine were estimated. There were significant associations between physical activity (high versus moderate versus poor) and all biomarkers (all p = 0.000, and p = 0.010 for γ-tocopherol). While total homocysteine and total antioxidant capacity were significantly associated with cognitive capacity (p = 0.000), vitamin E levels (e.g., α-tocopherol and γ-tocopherol) and nitric oxide (p = 0.354, 0.103 and 0.060, respectively) were not related to cognitive capacity in older adults. This study concludes that physical activity was associated with Vitamin E, oxidative stress markers, total homocysteine, and cognitive capacity in older adults. Although cognitive capacity was associated with total homocysteine and total antioxidant capacity, it was unrelated to vitamin E levels and nitric oxide in older adults.

One-carbon metabolism, cognitive impairment and CSF measures of Alzheimer pathology: homocysteine and beyond

Background

Hyperhomocysteinemia is a risk factor for cognitive decline and dementia, including Alzheimer disease (AD). Homocysteine (Hcy) is a sulfur-containing amino acid and metabolite of the methionine pathway. The interrelated methionine, purine, and thymidylate cycles constitute the one-carbon metabolism that plays a critical role in the synthesis of DNA, neurotransmitters, phospholipids, and myelin. In this study, we tested the hypothesis that one-carbon metabolites beyond Hcy are relevant to cognitive function and cerebrospinal fluid (CSF) measures of AD pathology in older adults.

Methods

Cross-sectional analysis was performed on matched CSF and plasma collected from 120 older community-dwelling adults with (n = 72) or without (n = 48) cognitive impairment. Liquid chromatography-mass spectrometry was performed to quantify one-carbon metabolites and their cofactors. Least absolute shrinkage and selection operator (LASSO) regression was initially applied to clinical and biomarker measures that generate the highest diagnostic accuracy of a priori-defined cognitive impairment (Clinical Dementia Rating-based) and AD pathology (i.e., CSF tau phosphorylated at threonine 181 [p-tau181]/β-Amyloid 1–42 peptide chain [Aβ_1–42] >0.0779) to establish a reference benchmark. Two other LASSO-determined models were generated that included the one-carbon metabolites in CSF and then plasma. Correlations of CSF and plasma one-carbon metabolites with CSF amyloid and tau were explored. LASSO-determined models were stratified by apolipoprotein E (APOE) ε4 carrier status.

Results

The diagnostic accuracy of cognitive impairment for the reference model was 80.8% and included age, years of education, Aβ_1–42, tau, and p-tau181. A model including CSF cystathionine, methionine, S-adenosyl-L-homocysteine (SAH), S-adenosylmethionine (SAM), serine, cysteine, and 5-methyltetrahydrofolate (5-MTHF) improved the diagnostic accuracy to 87.4%. A second model derived from plasma included cystathionine, glycine, methionine, SAH, SAM, serine, cysteine, and Hcy and reached a diagnostic accuracy of 87.5%. CSF SAH and 5-MTHF were associated with CSF tau and p-tau181. Plasma one-carbon metabolites were able to diagnose subjects with a positive CSF profile of AD pathology in APOE ε4 carriers.

Conclusions

We observed significant improvements in the prediction of cognitive impairment by adding one-carbon metabolites. This is partially explained by associations with CSF tau and p-tau181, suggesting a role for one-carbon metabolism in the aggregation of tau and neuronal injury. These metabolites may be particularly critical in APOE ε4 carriers.

Electronic supplementary material

The online version of this article (doi:10.1186/s13195-017-0270-x) contains supplementary material, which is available to authorized users.

Cognitive function in an elderly population: interaction between vitamin B12 status, depression, and apolipoprotein E ε4: the Hordaland Homocysteine Study

OBJECTIVE

To investigate the cross-sectional relation between metabolic markers of vitamin B(12) status and cognitive performance, and possible effect modification by the presence of depression and apolipoprotein E (ApoE) ε4.

METHODS

This is a population-based study of 1935 participants, aged 71 to 74 years, from Norway. Participants were administered a cognitive test battery, and vitamin B(12) status was assessed by measurements of plasma vitamin B(12), holotranscobalamin (holoTC), methylmalonic acid (MMA), and total homocysteine.

RESULTS

The geometric mean (95% confidence interval) for vitamin B(12) was 348 pM (341-354), whereas 5.9% of participants had vitamin B(12) levels lower than 200 pM. In linear regression analyses, holoTC (p = .039) and the holoTC/vitamin B(12) ratio (p = .013) were positively related, whereas MMA (p = .010) was inversely related, to global cognition, after adjustment for sex, education, ApoE status, plasma creatinine, and history of diabetes, cardiovascular disease, hypertension, and depression. Among those positive for ApoE ε4, but not among those without the ε4 allele, plasma vitamin B(12) was positively associated with global cognition (p = .015), whereas MMA was inversely related to global cognition (p = .036) and executive function (p = .014). In participants with depression, MMA was inversely associated with global cognition (p < .001) and episodic memory (p = .001).

CONCLUSIONS

Among the well-nourished elderly, low vitamin B(12) status is associated with cognitive deficit, particularly in those with the ApoE ε4 allele or with depression.

Serum vitamin B12, folic acid, and hemoglobin and cognition in Alzheimer's disease

Alzheimer's disease (AD) is a heterogeneous disorder that has a multifactorial etiology. No single factor can account for all cases by itself. Dietary surveys have shown that the elderly often have low intakes of vitamins and that their plasma or red blood cell folate levels are often low. Low blood levels of other nutrients like vitamin C, thiamine and 25-hydroxycholecalciferol have also been found to be common.

Cognitive and social profiles in two patients with cobalamin C disease

Cobalamin C (cblC) disease, an inborn error of vitamin B(12) metabolism, results in neurometabolic, neurochemical and neuroanatomical changes. Little is known of the long-term effects of the disorder on cognition and behaviour in children. Here, the complete neuropsychological profiles of two 12-year-old girls with cblC disease are presented. The two girls were tested longitudinally with standardized neuropsychological tests including intellectual ability, attention and memory, as well as executive, adaptive and behavioural function. The results indicate the presence of intellectual dysfunction, attention problems, and concerns with behavioural aspects of executive function. Both patients demonstrated a pattern of decreasing intellectual function over time, which may reflect a growing developmental gap in comparison with their same age peers. These impairments are in contrast to the relatively spared verbal expression and comprehension abilities, as well as strengths in sociability. The findings highlight a pattern of neuropsychological strengths and weaknesses that may distinguish cblC disease from other inborn errors of metabolism. Overt sociability such as observed in these two patients may actually mask underlying cognitive deficits because the patients appear to function at a more advanced level than that reflected by quantitative assessment of intellectual and cognitive functioning. This is of clinical and functional importance and suggests that accurate determination of cognitive, adaptive and social abilities necessitates an in-depth and broad evaluation. The presence of significant intellectual and cognitive deficits also underscores the need to document and monitor cognitive development in children with cblC disease and to consider remediative and adaptive learning strategies.

Vitamin B12 supplementation did not improve cognition but reduced delirium in demented patients with vitamin B12 deficiency

To examine the effects of vitamin B(12) supplementation on the cognitive function, delirium, and neuropsychiatric symptoms of mild to moderate dementia patients with vitamin B(12) deficiency. Thirty consecutive mild to moderate dementia cases aged over 60 years with low serum B(12) (< 200 pmol/l) were given vitamin B(12) supplementation for 40 weeks. The Mattis Dementia Rating Scale (MDRS), Category Verbal Fluency Test (CVFT), Delirium Rating Scale (DRS), Mini-Mental State Examination (MMSE), and the Neuropsychiatric Inventory (NPI) were performed at baseline, and after 6, 16, and 40 weeks. No significant changes in cognitive function and behavioral symptoms were detected between baseline and 40 weeks. DRS scores decreased significantly at 6 and 40 weeks (median change of -1 at both follow-ups, p=0.006 and 0.04, respectively). Cognitive function of mild to moderately demented older people with vitamin B(12) deficiency did not significantly change with vitamin B(12) supplementation over a 10-month period. The supplementation reduced delirium associated with dementia.

Vitamin B status and cognitive performance in preclinical and clinical Alzheimer's disease: data from the Kungsholmen Project

BACKGROUND/AIMS

The impact of vitamin B status on cognitive functioning in Alzheimer's disease (AD) is disputed. Using a population-based sample, we examined the associations of vitamin B(12) and folate with cognitive functioning in clinical (n = 44) and preclinical (n = 39) AD.

METHODS

The groups were subdivided in terms of low (<200 pmol/l) versus normal levels of B(12) and low (<13 nmol/l) versus normal folate levels. Participants were administered tests of verbal and nonverbal episodic memory, visuospatial abilities and verbal fluency.

RESULTS

As expected, the preclinical AD group performed better than the AD group across most cognitive tests. More interestingly, the effects of low vitamin B(12) and folate levels were negligible across all cognitive tests in clinical and preclinical AD.

CONCLUSION

These findings suggest that the influence of vitamin B deficiency on cognitive functioning is overshadowed by the neurodegenerative processes associated with AD.

Association between Helicobacter pylori infection and mild cognitive impairment

The association of Helicobacter pylori infection and Alzheimer's disease (AD) has recently been addressed, but no relative data exist regarding mild cognitive impairment (MCI), a prodromal phase of AD. The aim of this prospective study was to evaluate H. pylori infection, by histology in a Greek MCI cohort. Sixty-three consecutive patients with amnestic MCI and 35 normal controls underwent upper gastrointestinal endoscopy, histologic and serological examinations. The prevalence of H. pylori infection was 88.9% (56/63) in MCI patients and 48.6% (17/35) in anaemic controls, as confirmed by biopsy (P < 0.001, odds ratio: 8.47, 95% CI: 3.03-23.67). Mean serum anti-H. pylori IgG concentration and plasma total homocysteine (Hcy) titre were higher in MCI patients than controls (74.86 +/- 57.22 vs. 17.37 +/- 9.30 U/ml; and 16.03 +/- 4.28 vs. 13.5 +/- 1.20 micromol/l; P < 0.001 and P = 0.015, respectively). When compared with the anaemic participants, MCI patients exhibited more often multifocal (body and antral) gastritis (92.1% vs. 68.6%; P = 0.03); in H. pylori positive MCI patients cognitive state correlated with serum anti-H. pylori IgG concentration. In conclusion, H. pylori prevalence was significantly higher in MCI patients than controls. This infection might contribute, at least in part, to the pathophysiology of MCI, possibly through induction of chronic atrophic gastritis and elevated Hcy consequences.

Methylmalonic acid and cognitive function in the Medical Research Council Cognitive Function and Ageing Study

BACKGROUND

An elevated blood concentration of homocysteine is an established risk factor for cognitive impairment and dementia, but associations between cognition and methylmalonic acid (MMA), a related metabolic marker of vitamin B-12 deficiency, are less clear.

OBJECTIVE

The aim was to determine the utility of serum MMA and holotranscobalamin as markers of vitamin B-12 status in relation to cognitive function and to investigate their association with discrete cognitive domains.

DESIGN

This was a cross-sectional survey of 84 nondemented elderly participants (aged >69 y) from the Welsh cohort of the Medical Research Council's Cognitive Function and Ageing Study. Cognitive status was determined by Mini-Mental State Examination (MMSE) and the Cognitive Section of the Cambridge Mental Disorders of the Elderly Examination (CAMCOG).

RESULTS

Nearly one-half (43%) of the persons selected had likely metabolically significant vitamin B-12 deficiency. Higher MMA concentrations were associated with lower MMSE scores independent of age and education (P = 0.007). MMA concentration correlated inversely with CAMCOG scores of ideational praxis (P < 0.05) and language comprehension (P < 0.05) and expression (P < 0.01). Serum folate correlated weakly but significantly with language (P < 0.05), remote memory (P < 0.05), and constructional and ideational praxis scores (P < 0.05 and P < 0.01, respectively).

CONCLUSION

The high prevalence of likely metabolically significant vitamin B-12 deficiency in the elderly is associated with lower cognitive function scores and particularly with lower scores of language comprehension and expression.

Hematologic risk factors of vascular disease and their relation to dementia

Multiple studies have implicated vascular-related conditions as risk factors for dementia. Clarification of these factors in dementia is important because most are modifiable, and may serve as the basis for preventive strategies. Several hematologic factors are associated with vascular diseases, but their relation to dementia is unclear. This review examines biological and epidemiological evidence concerning the role of these hematologic factors in dementia, and dementia subtypes. Reviewed factors include homocysteine, cholesterol, fatty acids, antioxidants, and C-reactive protein. The vast majority of studies reviewed are cross-sectional. Longitudinal studies with serial hematologic measures are needed to clarify the relationship between these factors and dementia over the lifespan. A necessary step is to examine multiple hematologic factors simultaneously, rather than in isolation, to determine how these factors are interrelated.

Alzheimer's disease and Helicobacter pylori infection: Defective immune regulation and apoptosis as proposed common links

Although degenerative diseases of the central nervous system, including Alzheimer's disease (AD), have an increasingly high impact on aged population their association with Helicobacter pylori (H. pylori) infection has not as yet been thoroughly researched. Current H. pylori infection appears to induce irregular humoral and cellular immune responses that, owing to the sharing of homologous epitopes (molecular mimicry), cross-react with components of nerves, thereby contributing and possibly perpetuating the apoptotic neural tissue damage observed in neurodegenerative diseases including AD. An association between AD and H. pylori infection has been recently addressed by two studies. A higher seropositivity for anti-H. pylori immunoglobulin G antibodies in 30 patients with AD than in 30 age-matched controls was reported in one study; this serological test, however, has limitations because it does not discriminate between current and old infections. In the other study, by introducing the histological method (the actual gold standard) for diagnosis of H. pylori infection, we reported a higher prevalence of H. pylori infection in 50 AD patients than in 30 anemic controls. This pathogen may influence the pathophysiology of AD by promoting platelet and platelet-leukocyte aggregation; releasing various pro-inflammatory and vasoactive substances; developing cross-mimicry with host antigens; producing reactive oxygen metabolites and circulating lipid peroxides; influencing the apoptotic process; and increasing, through induction of atrophic gastritis, homocysteine, which contributes to vascular disorders implicated in endothelial damage and neurodegeneration.

Plasma homocysteine and vascular disease in psychogeriatric patients

BACKGROUND

There is a high frequency (40-50%) of elevated plasma total homocysteine (tHcy) concentrations in elderly patients with mental disorders, and patients with a history of vascular disease exhibit significantly higher plasma tHcy concentration than patients without vascular disease.

METHOD

The main objective of the present study was to further investigate the association between plasma tHcy concentration and vascular disease in psychogeriatric patients. We have therefore investigated 304 psychogeriatric patients and determined plasma tHcy and its most important determinants (folate and cobalamin status and renal function), and the natriuretic peptide N-terminal-pro brain natriuretic peptide (NT-proBNP). The patients were classified into several groups of vascular disease according to the findings of brain imaging and presence of a history/symptoms indicating manifest occlusive arteriosclerotic vascular disease.

RESULTS

Plasma tHcy concentration is associated with the presence of vascular disease in psychogeriatric patients. The presence of vascular disease is also associated with higher age, higher serum NT-proBNP, renal impairment and lower serum folate concentration than in patients without vascular disease. The significant association between plasma tHcy concentration and vascular disease remained after correction for age and for cystatin C differences between the groups of patients without and with vascular disease. In the present population with only 16% of the patients showing elevated plasma tHcy, renal function was a more important determinant for plasma tHcy concentration than folate status.

CONCLUSION

Plasma tHcy concentration is associated with vascular disease. In the present population of psychogeriatric patients renal function is associated with vascular disease and elevated plasma tHcy concentration. Thus, the association between plasma tHcy concentration and vascular disease might partially be explained by impairment of renal function.

Plasma homocysteine and markers of bone metabolism in psychogeriatric patients

OBJECTIVE

In recent studies high plasma total homocysteine (tHcy) levels were reported to be associated with increased risk of osteoporotic fractures. In elderly psychogeriatric patients there is a high frequency of elevated plasma tHcy concentration. The present study therefore investigates the association between plasma tHcy concentration and markers of bone metabolism in psychogeriatric patients.

MATERIAL AND METHODS

A total of 152 psychogeriatric patients were investigated and plasma tHcy and its major determinants (serum folate, serum cobalamin and renal function) were measured. Osteocalcin and crosslaps were chosen as markers of bone metabolism.

RESULTS

Bone markers (crosslaps and osteocalcin) were increased in elderly patients with dementia compared to patients without dementia. Stepwise multiple regression analysis showed that plasma tHcy concentration made only a small contribution to the prediction of crosslaps in serum, whereas plasma tHcy concentration was not an independent predictor of serum osteocalcin.

CONCLUSIONS

The present study does not provide support for the hypothesis that a moderately increased plasma tHcy concentration is a risk factor for impaired bone metabolism.

Circulating biomarkers of cognitive decline and dementia

Plasma and serum biochemical markers proposed for cognitive decline of degenerative (Alzheimer's disease, AD) or vascular origin and predementia syndromes (mild cognitive impairment and other related entities) are based on pathophysiologic processes such as lipoprotein metabolism (total cholesterol, apolipoprotein E, 24S-hydroxy-cholesterol), and vascular disease (homocysteine, lipoprotein(a)); SP formation (amyloid beta(Abeta)-protein, Abeta autoantibodies, platelet APP isoforms), oxidative stress (isoprostanes, vitamin E), and inflammation (cytokines). This review will focus on the current knowledge on circulating serum and plasma biomarkers of cognitive decline and dementia that are linked to cholesterol homeostasis and lipoprotein abnormalities, senile plaque formation and amyloid precursor protein (APP) metabolism, oxidative stress, and inflammatory reactions. Special emphasis will, however, be placed on biomarkers related to lipoprotein metabolism and vascular disease. Analytically, most plasma and serum proteins or metabolites lack reproducibility, sensitivity, or specificity for the diagnosis, risk and progression assessment, or therapeutic monitoring of AD and other dementing disorders. Measures linked to lipoprotein metabolism and vascular disease, APP metabolism, oxidative stress, or inflammation appear altered in AD relative to controls, but lack sufficient discriminatory power. Measures combining several biomarkers or incorporating a range of proteins in plasma and small molecule metabolites are promising approaches for the development of plasma or serum-based diagnostic tests for AD and other dementing disorders, as well as for predementia syndromes.

Low folate status is associated with impaired cognitive function and dementia in the Sacramento Area Latino Study on Aging

BACKGROUND

Low folate status is associated with poor cognitive function and dementia in the elderly. Since 1998, grain products in the United States have been fortified with folic acid, which has reduced the prevalence of folate deficiency and hyperhomocysteinemia.

OBJECTIVE

We investigated whether folate status is associated with cognitive function and dementia in a cohort of elderly Latinos (aged >or= 60 y; n = 1789) exposed to folic acid fortification.

DESIGN

Global cognitive function was assessed by the Modified Mini-Mental State Examination (3MSE) and specific cognitive functions by cross-culturally validated neuropsychological tests. Dementia was diagnosed according to the American Psychiatric Association Diagnostic and Statistical Manual of Mental Disorders, 3rd edition revised, and California Alzheimer Disease Diagnostic and Treatment criteria. Red blood cell (RBC) folate was measured by automated chemiluminescence and total plasma homocysteine by HPLC.

RESULTS

The prevalence of folate deficiency (RBC folate <or= 160 ng/mL) was <1%. After control for confounding by homocysteine, vitamin B-12, creatinine, demographic variables, and depressive symptom score, RBC folate was directly associated with 3MSE (P = 0.005) and delayed recall (P = 0.007) scores. In addition, adjusted odds ratios for low 3MSE score (<or=78) and dementia diagnosis per unit increase in RBC folate were significantly below unity (P <or= 0.008), which indicated that the relative risks of cognitive impairment and dementia decreased with increasing RBC folate concentration. In contrast, adjusted odds ratios for low 3MSE score and dementia diagnosis per unit increase in homocysteine were not significant.

CONCLUSION

RBC folate is directly associated with cognitive function scores and is inversely associated with dementia in elderly Latinos despite folic acid fortification.

Plasma homocysteine concentration and its relation to symptoms of vascular disease in psychogeriatric patients

BACKGROUND

There is a high frequency of elevated plasma total homocysteine (tHcy) concentrations in elderly patients with mental disorders. Psychogeriatric patients with a history of vascular disease exhibit a significantly higher plasma tHcy concentration than patients without vascular disease.

METHOD

The main reason for the present study is to further investigate the association between plasma tHcy concentration and vascular disease in psychogeriatric patients. We therefore investigated 152 psychogeriatric patients and determined plasma tHcy and its most important determinants (serum folate and serum cobalamin, serum cystatin C and serum creatinine). The patients were divided into two groups according to the presence of vascular disease. Eighty-seven patients had concomitant vascular disease. We also analysed the natriuretic peptide N-terminal pro brain natriuretic peptide (NT-proBNP) and protein S-100B in serum. NT-proBNP is a marker for congestive heart failure, whereas protein S-100B is a marker for brain damage.

RESULTS

The plasma tHcy concentration is elevated in the presence of dementia or vascular disease in psychogeriatric patients. The presence of dementia or vascular disease is also associated with higher age, renal impairment and lower serum folate concentration than in patients without dementia or vascular disease. Furthermore, we observed elevated serum concentrations of NT-proBNP in patients with dementia or vascular disease as a sign of poorer cardiovascular status. Likewise, protein S-100B concentrations were elevated in patients with dementia or vascular disease, possibly indicating brain damage in these groups of patients.

CONCLUSION

The high frequency of comorbidity of vascular disease and mental illness indicates a possibility to prevent and treat psychogeriatric disease by actively counteracting vascular disease in patients with psychogeriatric symptoms. Routine determination of NT-proBNP is valuable for obtaining information about cardiovascular status.

Homocysteine and brain atrophy

Homocysteine (Hcy) has been implicated as a risk factor for vascular disease as well as brain atrophy. There is evidence to implicate Hcy in increased oxidative stress, DNA damage, the triggering of apoptosis and excitotoxicity, all important mechanisms in neurodegeneration. Hcy is also prothrombotic and proatherogenic, and causes damage to the vessel wall. It is related to brain atrophy in older individuals, and possibly to white matter hyperintensities (WMH) in the brain. Epidemiological evidence and longitudinal data support Hcy as a risk factor for cognitive impairment and Alzheimer's Disease (AD). This may be due to cerebrovascular as well as direct neurotoxic mechanisms. Its role in Parkinson Disease (PD) is less well supported. High Hcy has been suggested as a mediating factor in alcohol-related brain atrophy. The high prevalence of hyperhomocysteinemia in the population and its easy treatability make Hcy an interesting amino acid for future intervention studies in the prevention of degenerative brain disorders. Intervention studies are necessary to confirm its aetiological role.

Homocysteine, vitamin B12 and folate in vascular dementia and in Alzheimer disease

The association between elevated plasma levels of homocysteine (Hcy) and nutritional status has been shown in Alzheimer disease (AD) patients and also in vascular dementia (VaD). Moreover, a previous study provided evidence that the relation between a high Hcy level and low vitamin B12 and folate levels in AD patients is due to biochemical damage, rather than a nutritional deficit. The purpose of this study was to investigate the relationship between plasma Hcy levels and vitamins involved in its metabolism in AD and VaD. Twenty-two VaD patients, 22 AD patients and 24 healthy subjects were studied for Hcy, vitamin B12, vitamin B6 and folate. All patients and control subjects were comparable for age, educational level, nutritional and socioeconomic status. None of them showed macrocytic anemia or impaired renal function. Hcy was significantly increased in VaD patients (26.0 +/- 6.58 micromol/l) as compared to controls (10.7 +/- 3.0 micromol/l) and AD patients (22.3 +/- 4.51 micromol/l; p<0.001); however, AD patients also showed increased levels of Hcy. Folates were significantly reduced in both VaD (10.8 +/- 2.81 nmol/l) and AD (10.0 +/- 2.72 nmol/l; p<0.001) patients, while vitamin B12 showed significantly reduced levels only in AD patients (392.1 +/- 65.32 pmol/l; p=0.02). Vitamin B6 was not significantly different in the three groups. Increased levels of Hcy associated with low vitamin B12 plasma levels were found only in AD patients. This observation led us to consider that vitamin B12 metabolism does not represent the direct consequence of the nutritional status and suggests that neuronal damage results in a functional vitamin B12 deficiency, as emphasized by recent reports. New therapeutic strategies are necessary, considering that available pharmaceutical forms of vitamin B12 are not utilized by neurons in oxidative stress conditions.

Effect of an enriched drink on cognitive function in frail elderly persons

BACKGROUND

Many elderly persons report that they have difficulties learning new things and remembering names, plans, and conversations. Because decreased cognitive function in elderly persons is potentially related to their poor nutritional status, provision of essential nutrients may improve cognitive function. The authors wanted to determine whether consumption of an enriched drink, including moderate doses of all essential micronutrients, improves cognitive function in frail elderly persons.

METHODS

Frail, white adults (n=101) who were aged 65 years or older with a body mass index<or=25 kg/m2 were selected for this randomized, double-blind, placebo-controlled trial. They received either an enriched drink or a placebo product for 6 months. Before and after the intervention, participants' cognitive function was assessed (word learning test [WLT], WLT delayed, category fluency [CF] for animals and professions, and recognition memory test for words [RMTW]) and blood biochemical analyses (vitamin B12, homocysteine) were performed.

RESULTS

Sixty-seven residents completed the study period. After 6 months, significant differences were noted in changes of the WLT (0.9+/-0.3 vs -0.1+/-0.3; p=.014) and CF professions (1.2+/-0.7 vs -0.6+/-0.5; p=.017) in the supplement group (n=34) compared with the placebo group (n=33). No significant differences were observed in WLT delayed, RMTW, and CF animals. The plasma vitamin B12 concentration increased (105+/-50 vs 8 +/-16; p=.003) and the homocysteine concentration decreased (-6.3+/-5.9 vs -0.3+/-2.9; p=.000) in the supplement group compared with the placebo group.

CONCLUSIONS

This study contributes to the evidence that nutritional supplementation may improve neuropsychological performance in frail elderly persons.

Clinical utility of serum holotranscobalamin as a marker of cobalamin status in elderly patients with neuropsychiatric symptoms

Early diagnosis of cobalamin deficiency is crucial, owing to the latent nature of this disorder and the resulting possible irreversible neurological damage. A normal serum cobalamin concentration does not reliably rule out a functional cobalamin deficiency and there does not at present seem to be any single diagnostic approach to achieve this diagnosis. A new marker for cobalamin status is the serum concentration of cobalamin bound to transcobalamin II (holoTC). Because methods suitable for routine use have been unavailable until recently, the clinical value of low holoTC is still uncertain. Furthermore, there is at the moment no gold standard or true reference method to diagnose subtle cobalamin deficiency, which makes evaluation of the clinical usefulness of holoTC and the estimation of sensitivity and specificity problematic. In this study, we aimed to assess whether low holoTC concentrations are congruent with other biochemical signs of cobalamin deficiency in a group of psychogeriatric patients. The findings in the present study show that holoTC is strongly related to serum cobalamin (0.68; p<0.001 in both patients and controls). Distribution of the different markers for cobalamin/folate status in the 33 patients with low levels of serum holoTC (below 40 pmol/l) showed that 17 patients had normal levels of the other markers for cobalamin status. This may indicate poor specificity of low holoTC for cobalamin deficiency. In 23 out of 176 patients with normal levels of holoTC we observed pathological levels of other markers for cobalamin deficiency. The use of holoTC in the present study group did not give significant additional information other than that given by serum cobalamin and therefore cannot be recommended in this clinical setting.

Cobalamin: a critical vitamin in the elderly

Vitamin B(12) deficiency is a common problem in elderly subjects. If a serum cobalamin level of about 150 pmol/L (200 pg/mL) is considered normal, 10-15% of the elderly are deficient. Today, however, a threshold of 220-258 pmol/L (300-350 pg/mL) is recognized as desirable in the elderly, or else sensitive markers like the blood concentration of homocysteine or methylmalonic acid (MMA) are used. Then the prevalence of cobalamin deficiency rises to up to 43%. In the elderly, this high prevalence of poor cobalamin status is predominantly caused by atrophic gastritis type B. Atrophic gastritis results in declining gastric acid and pepsinogen secretion, and hence decreasing intestinal absorption of the cobalamin protein complexes from food. About 20-50% of the elderly are affected. Furthermore, the reduced acid secretion leads to an alkalinization of the small intestine, which may result in bacterial overgrowth and thus to a further decrease of the bioavailability of the vitamin. In addition, some drugs such as proton pump inhibitors or H2 receptor antagonists inhibit the intestinal absorption of vitamin B(12). An already moderately reduced vitamin B(12) level is associated with vascular disease and neurocognitive disorders such as depression and impaired cognitive performance. Furthermore, a poor vitamin B(12) status is assumed to be involved in the development and progression of dementia (e.g., Alzheimer's dementia). This is especially observable if the folic acid status is reduced as well. Due to the insecure supply, the cobalamin status of elderly persons (>/=60 years) should be regularly controlled and a general supplementation with vitamin B(12) (>50 microg/day) should be considered.

Helicobacter pylori and Alzheimer's disease: a possible link

BACKGROUND: Although serological findings indicate the presence of a relationship between Helicobacter pylori (HP) and vascular disease, no data have been reported about a possible association of HP with dementia. The aim of the present study was to determine whether chronic HP infection might play a role in Alzheimer's disease (AD). METHODS: Plasma homocysteine level, serum folate and vitamin B(12) concentrations, plasma pyridoxal phosphate level, IgG and IgA antibodies to HP, and C-reactive protein (CRP) were determined in 30 AD patients, 30 patients affected by vascular dementia (VaD), and 30 control subjects. All patients and control subjects were matched for age, educational level, and nutritional and socioeconomic status. None of the subjects had a history of chronic gastritis, peptic ulcer, gastric cancer, or major abdominal surgery. RESULTS: HP-IgG level was significantly increased in VaD patients as compared to controls and AD patients, while AD patients had HP-IgG levels higher than those of normal controls. HP-IgA levels were equally increased in both VaD and AD patients. CRP was higher in AD patients than in VaD patients and controls, although CRP levels in VaD patients were also significantly increased. CONCLUSIONS: The present study found an association between HP infection and AD. The question remains as to whether this association is due to the ubiquity of HP, or whether it contributes to the neuroinflammatory process in AD. The relationship between HP and AD, if confirmed by additional studies with a greater number of patients, may have important clinical and therapeutic implications.

Homocisteína e transtornos psiquiátricos

O autor apresenta uma visão geral da literatura atual sobre homocisteína como um fator de risco para os transtornos neuropsiquiátricos. Foram pesquisados os bancos de dados MEDLINE, Current Contents e EMBASE (entre 1966 e 2002) para publicações em língua inglesa utilizando as palavras-chave ''Homocisteína'' e ''AVC''; ''Doença de Alzheimer''; ''Déficit Cognitivo'', ''Epilepsia'', ''Depressão'' ou ''Doença de Parkinson''. Artigos individuais foram pesquisados para referências cruzadas relevantes. É biologicamente plausível que altos níveis de homocisteína possam causar lesão cerebral e transtornos neuropsiquiátricos. A homocisteína é pró-aterogênica e pró-trombótica. Dessa forma, aumenta o risco de acidente vascular cerebral, podendo ter um efeito neurotóxico direto. Evidências de que a homocisteína seja um fator de risco para doença microvascular cerebral são conflitantes, mas justificam maiores estudos. Estudos transversais e alguns longitudinais suportam a crescente prevalência de acidente vascular cerebral e demência vascular em indivíduos com hiper-homocisteinemia. As evidências de crescente neurodegeneração estão se acumulando. A relação com a depressão ainda é experimental, da mesma forma como com a epilepsia. Atualmente, estudos sobre tratamentos são necessários para colocar as evidências sobre bases mais sólidas. Os pacientes de alto risco também devem ser pesquisados para hiper-homocisteínemia, cujo tratamento deve ser feito com ácido fólico. Mais evidências são necessárias antes que pesquisas populacionais possam ser recomendadas.

Reported symptoms and clinical findings in relation to serum cobalamin, folate, methylmalonic acid and total homocysteine among elderly Swedes: a population-based study

OBJECTIVES

The early stages of tissue B12 or folate deficiency often cause diagnostic problems. In this report, the levels of serum cobalamin, folate, methylmalonic acid (MMA) and total homocysteine (tHcy), and their relationships with clinical findings and reported symptoms in a representative random population sample are presented.

DESIGN

Cohort study.

SETTING

A general central Swedish population 70 years or older.

SUBJECTS AND METHODS

A 20% random sample of persons 70 years or older in a defined geographical area were invited to a survey. A total of 235 (85%) persons responded, of whom 161 had no interfering diseases or medication. Blood specimens for serum cobalamin, folate, MMA and tHcy analyses were drawn.

MAIN OUTCOME MEASURES

Presence of anaemic, gastrointestinal, neurological and psychiatric symptoms, obtained by questionnaire, and vibration sense measurement and findings at a physical and Mini Mental State Examination.

RESULTS

Among a large number of symptoms and clinical findings that traditionally have been linked to vitamin B12 or folate tissue deficiency, only changes in the tongue mucosa and mouth angle stomatitis turned out to be significantly associated with abnormal serum tHcy and serum folate levels. There were no relationships to serum cobalamin and serum MMA.

CONCLUSIONS

Changes in the oral mucosa were the only signs and symptoms found in this study, indicating that these may be the very early markers of metabolic defects. The traditional symptoms of vitamin deficiency may appear later in the course.

Homocysteine and cognitive function in the Sacramento Area Latino Study on Aging

BACKGROUND

Elevated plasma homocysteine (hyperhomocysteinemia), an independent risk factor for vascular disease, has been reported to be inversely correlated with objective measures of cognitive function in patients with Alzheimer disease and in community-dwelling older adults.

OBJECTIVE

We evaluated the cross-sectional relation between total plasma homocysteine concentration and cognitive function in elderly Latinos (aged > or = 60 y; n = 1789) participating in the Sacramento Area Latino Study on Aging.

DESIGN

Global cognitive function was assessed by using the Modified Mini-Mental State Examination, and specific cognitive functions were assessed by using 6 instruments developed for cross-cultural and multilingual neuropsychological evaluation of older persons. Associations between the cognitive function scores and total plasma homocysteine concentrations were then measured by multiple regression analysis with control for potential confounding by nutrient status (red blood cell folate, plasma vitamin B-12), kidney function (serum creatinine), demographic variables (age, sex, education, acculturation), and depressive symptoms.

RESULTS

Modest inverse associations were found between homocysteine concentrations and several indexes of cognitive function, including the global Modified Mini-Mental State Examination assessment and the picture-association, verbal attention-span, and pattern-recognition tests (P < or = 0.05). Demographic variables, particularly age and education, were more strongly associated with cognitive function scores than was homocysteine.

CONCLUSIONS

Homocysteine is a modest independent predictor of cognitive function in community-dwelling elderly Latinos. Reducing plasma homocysteine concentrations by administering B-vitamin supplements may provide some protection against cognitive decline in this and other elderly populations, but the effect may be limited.

Position of the American Dietetic Association and Dietitians of Canada: vegetarian diets

It is the position of the American Dietetic Association and Dietitians of Canada that appropriately planned vegetarian diets are healthful, nutritionally adequate, and provide health benefits in the prevention and treatment of certain diseases. Approximately 2.5% of adults in the United States and 4% of adults in Canada follow vegetarian diets. A vegetarian diet is defined as one that does not include meat, fish, or fowl. Interest in vegetarianism appears to be increasing, with many restaurants and college foodservices offering vegetarian meals routinely. Substantial growth in sales of foods attractive to vegetarians has occurred and these foods appear in many supermarkets. This position paper reviews the current scientific data related to key nutrients for vegetarians including protein, iron, zinc, calcium, vitamin D, riboflavin, vitamin B-12, vitamin A, n-3 fatty acids, and iodine. A vegetarian, including vegan, diet can meet current recommendations for all of these nutrients. In some cases, use of fortified foods or supplements can be helpful in meeting recommendations for individual nutrients. Well-planned vegan and other types of vegetarian diets are appropriate for all stages of the life-cycle including during pregnancy, lactation, infancy, childhood, and adolescence. Vegetarian diets offer a number of nutritional benefits including lower levels of saturated fat, cholesterol, and animal protein as well as higher levels of carbohydrates, fibre, magnesium, potassium, folate, antioxidants such as vitamins C and E, and phytochemicals. Vegetarians have been reported to have lower body mass indices than non-vegetarians, as well as lower rates of death from ischemic heart disease, lower blood cholesterol levels, lower blood pressure, and lower rates of hypertension, type 2 diabetes, and prostate and colon cancer. While a number of federally funded and institutional feeding programs can accommodate vegetarians, few have foods suitable for vegans at this time. Because of the variability of dietary practices among vegetarians, individual assessment of dietary intakes of vegetarians is required. Dietetics professionals have a responsibility to support and encourage those who express an interest in consuming a vegetarian diet. They can play key roles in educating vegetarian clients about food sources of specific nutrients, food purchase and preparation, and any dietary modifications that may be necessary to meet individual needs. Menu planning for vegetarians can be simplified by use of a food guide that specifies food groups and serving sizes.

Position of the American Dietetic Association and Dietitians of Canada: Vegetarian diets

It is the position of the American Dietetic Association and Dietitians of Canada that appropriately planned vegetarian diets are healthful, nutritionally adequate, and provide health benefits in the prevention and treatment of certain diseases. Approximately 2.5% of adults in the United States and 4% of adults in Canada follow vegetarian diets. A vegetarian diet is defined as one that does not include meat, fish, or fowl. Interest in vegetarianism appears to be increasing, with many restaurants and college foodservices offering vegetarian meals routinely. Substantial growth in sales of foods attractive to vegetarians has occurred, and these foods appear in many supermarkets. This position paper reviews the current scientific data related to key nutrients for vegetarians, including protein, iron, zinc, calcium, vitamin D, riboflavin, vitamin B-12, vitamin A, n-3 fatty acids, and iodine. A vegetarian, including vegan, diet can meet current recommendations for all of these nutrients. In some cases, use of fortified foods or supplements can be helpful in meeting recommendations for individual nutrients. Well-planned vegan and other types of vegetarian diets are appropriate for all stages of the life cycle, including during pregnancy, lactation, infancy, childhood, and adolescence. Vegetarian diets offer a number of nutritional benefits, including lower levels of saturated fat, cholesterol, and animal protein as well as higher levels of carbohydrates, fiber, magnesium, potassium, folate, and antioxidants such as vitamins C and E and phytochemicals. Vegetarians have been reported to have lower body mass indices than nonvegetarians, as well as lower rates of death from ischemic heart disease; vegetarians also show lower blood cholesterol levels; lower blood pressure; and lower rates of hypertension, type 2 diabetes, and prostate and colon cancer. Although a number of federally funded and institutional feeding programs can accommodate vegetarians, few have foods suitable for vegans at this time. Because of the variability of dietary practices among vegetarians, individual assessment of dietary intakes of vegetarians is required. Dietetics professionals have a responsibility to support and encourage those who express an interest in consuming a vegetarian diet. They can play key roles in educating vegetarian clients about food sources of specific nutrients, food purchase and preparation, and any dietary modifications that may be necessary to meet individual needs. Menu planning for vegetarians can be simplified by use of a food guide that specifies food groups and serving sizes.

News and views on folate and elderly persons

Elderly persons are especially exposed to folate deficiency, where normal/subnormal folate levels do not exclude tissue deficiency. Accompanying diseases, medication, and lifestyle factors may contribute to/cause deficiency. Symptoms of deficiency can be hematological, neurological, or neuropsychiatric, but it is likely that there are also cardiovascular manifestations as well as associations with malignancies. The physician should make an individualized investigation to establish the probable cause. Among the available determinants of the folate/cobalamin state, plasma homocysteine (Hcy) is a swift and sensitive marker and has the strongest connection to cognitive function. The association is generally stronger between Hcy levels and symptoms than between vitamin-related levels and symptoms. The duration as well as the severity of symptoms are of importance in terms of the improvement of neurological and neuropsychiatric symptoms when substitution is performed. The issue of general folate fortification of flour is complex, and there are as many pros and cons as there are countries in which it is considered to be launched. It is important to bear in mind that in our modern society, deficiency of folate/cobalamin--overt or latent--mainly is a problem of the elderly and a challenge to the doctor.

Folate deficiency is a common finding in psychogeriatric patients

BACKGROUND AND AIMS

In previous studies we observed a high frequency of elevated total plasma homocysteine (tHcy) concentrations in psychogeriatric patients. The objective of the present study was to obtain detailed information on folate status in psychogeriatric patients and its association with elevated tHcy concentration.

METHODS

We measured serum and blood folate, tHcy, serum cobalamin, and serum methylmalonic acid in a study population consisting of 141 psychogeriatric patients, 49 of whom had elevated tHcy concentration.

RESULTS

The concentrations of serum and blood folate showed a high correlation and were significantly lower, and age significantly higher, in patients with elevated tHcy compared to patients with normal concentrations of tHcy. A stepwise multiple regression analysis including age, serum and blood folate, serum cobalamin, serum methylmalonic acid and serum creatinine showed that only serum creatinine (p<0.001), age (p<0.01), serum folate (p<0.05) and blood folate (p<0.05) independently predicted tHcy concentration. Only one patient of those with serum folate above 12 nmo/L had an elevated tHcy concentration. No such clear limit was observed for the relation between tHcy and blood folate. Thirty-two of the patients with elevated tHcy had decreased serum folate concentrations (<7.0 nmol/L), and seven of these patients also had signs of cobalamin deficiency. Ten patients had only signs of cobalamin deficiency.

CONCLUSIONS

Folate deficiency appears to be common in psychogeriatric patients, and serum folate seems to reflect folate deficiency better than blood folate. Our findings suggest the use of tHcy, serum cobalamin and serum folate to evaluate cobalamin-folate status in psychogeriatric patients.

Optimal use of markers for cobalamin and folate status in a psychogeriatric population

BACKGROUND

Cobalamin/folate deficiency is common in elderly subjects and may lead to psychiatric symptoms, but even more often it increases the severity of other organic and non-organic mental diseases. It is therefore of importance to evaluate the optimal use of different markers of cobalamin/folate status in a psychogeriatric population.

METHODS

We measured serum cobalamin, blood folate, plasma homocysteine (tHcy) and serum methylmalonic acid (MMA) in 475 well-defined psychogeriatric patients.

RESULTS

The findings in the present study showed that many (41%) of the patients with normal levels of serum MMA (< 0.41 micromol/l) had pathological values of at least one of the other markers for cobalamin/folate status, whereas only 17% of patients with normal plasma tHcy (< 19.9 micromol/l) had pathological levels of other markers. If patients with decreased levels of serum cobalamin and/or blood folate were also excluded from these patients, only nine patients with slightly elevated levels of serum MMA remained. In the present study different upper reference limits were also tested for both serum MMA and plasma tHcy. However, the use of these limits did not cause any diagnostic improvement in the evaluation of cobalamin-folate status. Plasma tHcy was increased in almost all diagnosis groups of the psychogeriatric patients, whereas serum MMA was increased in only some groups. The distribution of the two common polymorphisms of the methylenetetrahydrofolate reductase gene (C677T and A1298C) was similar in patients with elevated and normal plasma tHcy.

CONCLUSIONS

The findings in the present study suggest the use of plasma tHcy, serum cobalamin and blood folate to evaluate cobalamin-folate status in psychogeriatric patients and to omit the use of serum MMA.

Homocysteine in neuropsychiatric disorders of the elderly

OBJECTIVE

There is increasing interest in homocysteine as a risk factor for neuropsychiatric disorders such as stroke, dementia, depression and Parkinson's disease. This article reviews the current literature on the relationship between homocysteine and these disorders to ascertain if any clinical recommendations can be made.

METHOD

A MEDLINE and EMBASE search was made for English language publications between 1966 and 2002 using the search terms 'Homocysteine' and 'Stroke', 'Dementia', 'Vascular Dementia', 'Alzheimer's dementia', 'Cognition disorders or cognitive decline or memory disorders', 'Depression or depressive disorders' or 'Parkinson's disease'. In addition, individual articles were hand searched for relevant references.

RESULTS

Cross-sectional studies consistently suggest that elevated homocysteine increases the risk of stroke, and may also increase the risk of leukoariosis, vascular dementia (VaD), cognitive impairment and Alzheimer's disease (AD). Longitudinal studies of homocysteine as a risk factor are few and inconsistently supportive of these associations. No intervention trials to determine the effect of lowering homocysteine levels have yet been published. The pathological mechanisms for homocysteine-mediated disease await complete elucidation. Mild hyperhomocysteinemia is common in the elderly population, and folate supplementation can decrease homocysteine levels.

CONCLUSION

The epidemiological evidence for homocysteine as a risk factor for neuropsychiatric disease is an emerging area of great interest. Screening the population for hyperhomocysteinemia cannot be recommended at this stage, but individuals at increased risk of cerebrovascular disease or cognitive impairment should be investigated and treated for elevated homocysteine levels.

Relationship between total homocysteine and folate levels in pregnant women and their newborn babies according to maternal serum levels of vitamin B12

OBJECTIVE

To determine total homocysteine and folate levels in pregnant women according to vitamin B12 (B12) levels, and to analyse the impact of maternal B12 levels on the nutritional status of their newborn babies.

DESIGN

Cross sectional observational study.

SETTING

Two public hospitals in Jundiai City, São Paulo, Brazil.

SAMPLE

Sixty-nine pregnant women and their respective newborn babies at the time of delivery.

METHODS

Maternal blood was collected up to 8 hours before delivery. Umbilical cord blood was collected after the expulsion of the placenta. Total homocysteine was measured by high perfomance liquid chromatography, folate by ion capture methodology and B12 by enzyme immunoassay.

MAIN OUTCOME MEASURES

Relationship between low maternal vitamin B12 levels and total homocysteine and folate levels in pregnant women and newborn babies.

RESULTS

There was a significant correlation between maternal and neonatal B12 levels, but not between maternal B12 and neonatal red blood cell (RBC) folate. There was a weak correlation between maternal B12 levels and neonatal serum folate. However, there were significant correlations between maternal and neonatal total homocysteine levels and between neonatal B12 and neonatal total homocysteine levels. Mean (+/- SD) umbilical cord blood B12, RBC folate, serum folate and total homocysteine levels were 1.7 +/- 0.8, 1.8 +/- 0.8, 2.2 +/- 0.8 and 0.9 +/- 0.3 times higher than maternal B12, RBC folate, serum folate and total homocysteine values, respectively.

CONCLUSIONS

These data suggest that pregnant women with low B12 levels are unable to provide the necessary amount of B12 to their fetuses. The clinical consequences could be the presence of neurological abnormalities as well as the lack of utilisation of homocysteine for methionine transformation.

Biochemical markers related to Alzheimer's dementia in serum and cerebrospinal fluid

The diagnosis of Alzheimer's disease (AD) is currently based on clinical and neuropsychological examination. To date there is no blood test available that can discriminate dementia patients from healthy individuals. In the present paper, an overview of the current state of knowledge on biologic markers in serum (plasma) and CSF is presented. The combination of characteristic plaque markers tau and amyloid bèta may constitute a specific and sensitive CSF marker for AD. Glial fibrillary acidic protein and antibodies in CSF may be a marker for severe neurodegeneration. CSF concentrations of the oxidative stress markers 3-nitrotyrosine, 8-hydroxy-2'-deoxyguanosine and isoprostanes are increased in AD patients. Serum 24S-OH-cholesterol may be an early whereas glial fibrillary acidic protein autoantibody level may be a late marker for neurodegeneration. To date, serum alpha(1)-Antichymotripsin concentration is the most convincing marker for CNS inflammation. Increased serum homocysteine concentrations have also been consistently reported in AD. In summary, a large overlap in mean concentrations has been observed in studies comparing AD patients with healthy controls for single markers. These studies together support the theory of testing several serum markers in combination for the diagnosis of AD.

Markers for the functional availability of cobalamin/folate and their association with neuropsychiatric symptoms in the elderly

Cobalamin/folate deficiency is common in elderly subjects and may lead to psychiatric symptoms, but even more often it increases the severity of other organic and non-organic mental diseases. This paper reviews the literature relevant for markers of cobalamin/folate status and their relation to neuropsychiatric symptoms in the elderly. Plasma homocysteine, a marker of cobalamin/folate status, is frequently increased in psychogeriatric patients. Among markers of cobalamin/folate status, plasma homocysteine shows the best association with neuropsychiatric dysfunction.

Homocysteine, vascular dementia and Alzheimer's disease

There is some evidence from recent observational studies that hyperhomocysteinemia is a risk factor for cognitive dysfunction, including Alzheimer's disease and vascular dementia. There are only a few intervention studies, and the results are disappointing for such a frequent disease. Prospective double-blind and placebo-controlled intervention studies are not available. If homocysteine-lowering therapy will be in the running for the prevention and treatment of dementia, we must be able to diagnose the disease at a preclinical stage (i.e. 5 or 10 or 20 years before the disease becomes clinically overt for Alzheimer's disease). At the moment, there are insufficient data to support a vitamin B12, B6 or folate therapy in the prevention or treatment of patients with dementia.

Improvement of cognitive functions after cobalamin/folate supplementation in elderly patients with dementia and elevated plasma homocysteine

OBJECTIVES

To investigate the effect of cobalamin/folate supplementation on cognitive function in elderly patients with dementia.

METHOD

The cobalamin/folate status of the patients was evaluated by measuring plasma homocysteine, serum methylmalonic acid, serum cobalamin and blood folate. Thirty-three patients were studied and repeatedly assessed with the Mini-Mental State Examination (MMSE) and 'A short cognitive performance test for assessing memory and attention' (SKT) during vitamin substitution.

RESULTS

Patients with mild-moderate dementia and elevated plasma homocysteine levels improved clinically with increased test scores after vitamin substitution, while severely demented patients and patients with normal plasma homocysteine levels did not improve clinically.

CONCLUSIONS

Plasma homocysteine may be the best marker for detecting treatable cobalamin/folate deficiency in patients with dementia.

Vitamin B(12) and folate in relation to the development of Alzheimer's disease

OBJECTIVE

To explore the associations of low serum levels of vitamin B(12) and folate with AD occurrence.

METHODS

A population-based longitudinal study in Sweden, the Kungsholmen

PROJECT

A random sample of 370 nondemented persons, aged 75 years and older and not treated with B(12) and folate, was followed for 3 years to detect incident AD cases. Two cut-off points were used to define low levels of vitamin B(12) (< or =150 and < or =250 pmol/L) and folate (< or =10 and < or =12 nmol/L), and all analyses were performed using both definitions. AD and other types of dementia were diagnosed by specialists according to DSM-III-R criteria.

RESULTS

When using B(12) < or =150 pmol/L and folate < or =10 nmol/L to define low levels, compared with people with normal levels of both vitamins, subjects with low levels of B(12) or folate had twice higher risks of developing AD (relative risk [RR] = 2.1, 95% CI = 1.2 to 3.5). These associations were even stronger in subjects with good baseline cognition (RR = 3.1, 95% CI = 1.1 to 8.4). Similar relative risks of AD were found in subjects with low levels of B(12) or folate and among those with both vitamins at low levels. A comparable pattern was detected when low vitamin levels were defined as B(12) < or =250 pmol/L and folate < or =12 nmol/L.

CONCLUSIONS

This study suggests that vitamin B(12) and folate may be involved in the development of AD. A clear association was detected only when both vitamins were taken into account, especially among the cognitively intact subjects. No interaction was found between the two vitamins. Monitoring serum B(12) and folate concentration in the elderly may be relevant for prevention of AD.