Cobalamin levels are not reduced in Alzheimer's disease: results from a population-based study

Plasma Homocysteine and Serum Folate and Vitamin B12 Levels in Mild Cognitive Impairment and Alzheimer's Disease: A Case-Control Study

Homocysteine (Hcy) is a risk factor for brain atrophy, cognitive impairment, and dementia. Vitamin B₁₂ and folate are cofactors necessary for the methylation of Hcy. However, there is some debate regarding the differing levels of plasma Hcy and serum folate and vitamin B₁₂ among healthy controls, patients with mild cognitive impairment (MCI), and patients with Alzheimer’s disease (AD). This study aimed to evaluate how the levels of plasma Hcy and its biological determinants, folate and vitamin B₁₂, are related to MCI and AD in older Chinese adults. This is a case-control study including 112 subjects with MCI, 89 AD patients and 115 healthy controls. Diagnosis of AD was made according to the NINCDS-ADRDA and MCI with modified Petersen’s criteria. Serum folate and vitamin B₁₂ concentrations were analyzed by radioimmunoassay, and plasma Hcy was assessed by a high-performance liquid chromatography-fluorescence method. Multivariate analysis of regression was used to examine the odds ratio (OR) of MCI or AD with Hcy or vitamin levels. Results have shown that serum folate and vitamin B₁₂ levels were significantly lower, but the plasma Hcy level was higher, in patients with MCI and AD than in healthy controls. Multivariate regression analyses showed that subjects in the lowest folate tertile had significantly higher adjusted ORs for MCI (OR: 3.07; 95% confidence interval [CI]: 1.12, 8.07) and AD (3.42; 95% CI: 1.15, 8.34) compared to subjects in the highest tertile. The highest Hcy tertile was significantly associated with MCI (adjusted OR: 2.81; 95% CI: 1.15, 4.73) and AD (adjusted OR: 3.64; 95% CI: 1.13, 9.04) compared to the lowest tertile. No association existed between low vitamin B₁₂ levels and AD or MCI (p > 0.05). Low blood levels of folate and vitamin B₁₂ and elevated Hcy levels were associated with MCI and AD in older Chinese adults, and the association was stronger for AD.

Serum folic acid and RFC A80G polymorphism in Alzheimer's disease and vascular dementia

Low level of vitamin B12 and folic acid has been reported to play an important role in the pathogenesis of Alzheimer's disease (AD) and vascular dementia (VaD). Serum folic acid and vitamin B12 were assayed in 80 AD and 50 VaD cases and in 120 healthy controls. The reduced folate carrier (RFC1) gene, rs1051266, which encodes the RFC 1, protein was analyzed for polymorphism by polymerase chain reaction-restriction fragment length polymorphism. It was observed that the patients having folic acid <8.45 ng/mL had 2.4 (95% confidence interval [CI]: 1.4-4.5) times higher odds of having AD and 2.1 (95% CI: 1.1-4.2) times higher odds of having VaD than patients having folic acid ≥8.45 ng/mL. Serum vitamin B12 level did not show any such statistically significant effect in altering the odds. No direct association was found between variant (G) allele or genotype of rs1051266 with AD and VaD cases. On serum folate level no association was observed with gene polymorphism.

Plasma nutrient status of patients with Alzheimer's disease: Systematic review and meta-analysis

BACKGROUND

Alzheimer disease (AD) patients are at risk of nutritional insufficiencies because of physiological and psychological factors. Nutritional compounds are postulated to play a role in the pathophysiological processes that are affected in AD. We here provide the first systematic review and meta-analysis that compares plasma levels of micronutrients and fatty acids in AD patients to those in cognitively intact elderly controls. A secondary objective was to explore the presence of different plasma nutrient levels between AD and control populations that did not differ in measures of protein/energy nourishment.

METHODS

We screened literature published after 1990 in the Cochrane Central Register of Controlled Trials, Medline, and Embase electronic databases using Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines for AD patients, controls, micronutrient, vitamins, and fatty acids, resulting in 3397 publications, of which 80 met all inclusion criteria. Status of protein/energy malnutrition was assessed by body mass index, mini nutritional assessment score, or plasma albumin. Meta-analysis, with correction for differences in mean age between AD patients and controls, was performed when more than five publications were retrieved for a specific nutrient.

RESULTS

We identified five or more studies for folate, vitamin A, vitamin B12, vitamin C, vitamin D, vitamin E, copper, iron, and zinc but fewer than five studies for vitamins B1 and B6, long-chain omega-3 fatty acids, calcium, magnesium, manganese, and selenium (the results of the individual publications are discussed). Meta-analysis showed significantly lower plasma levels of folate and vitamin A, vitamin B12, vitamin C, and vitamin E (P < .001), whereas nonsignificantly lower levels of zinc (P = .050) and vitamin D (P = .075) were found in AD patients. No significant differences were observed for plasma levels of copper and iron. A meta-analysis that was limited to studies reporting no differences in protein/energy malnourishment between AD and control populations yielded similar significantly lower plasma levels of folate and vitamin B12, vitamin C, and vitamin E in AD.

CONCLUSIONS

The lower plasma nutrient levels indicate that patients with AD have impaired systemic availability of several nutrients. This difference appears to be unrelated to the classic malnourishment that is well known to be common in AD, suggesting that compromised micronutrient status may precede protein and energy malnutrition. Contributing factors might be AD-related alterations in feeding behavior and intake, nutrient absorption, alterations in metabolism, and increased utilization of nutrients for AD pathology-related processes. Given the potential role of nutrients in the pathophysiological processes of AD, the utility of nutrition may currently be underappreciated and offer potential in AD management.

Vitamin B12 deficiency associated with symptoms of frontotemporal dementia

We report the case of an elderly patient with cobalamin deficiency who progressively developed cognitive and behavioral symptoms associated with neuropsychiatric disturbances. His neuropsychological profile showed many features suggestive for a frontal-dysexecutive syndrome and was related to a predominant asymmetric (right > left) frontal lobe hypoperfusion. He completely recovered after a treatment with vitamin B12 and follow-up of 7 years showed that his improvement remained stable. Along with the other cases reported in the literature, our case also proves that there are some cases of vitamin B12 deficiency that can manifest with the symptoms of frontotemporal dementia and that they are completely reversible after substitution therapy.

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.

Low Folate and the Risk of Cognitive and Functional Deficits in the Very Old: The Monzino 80-plus Study

OBJECTIVE

To cross sectionally investigate the association of serum vitamin B(12) and folate concentrations with cognitive and functional ability in the very old in the general population.

METHODS

Serum vitamin B(12) and folate concentrations were assessed in 471 consenting subjects participating in the Monzino 80-plus study (mean age: 87.4 years), a door-to-door population-based survey among very old subjects living in Northern Italy. Cognitive and functional evaluations included Mini-Mental State Examination (MMSE), Instrumental Activities of Daily Living (IADL) and Spontaneous Behavior Interview-basic Activities of Daily Living (SBI-bADL).

RESULTS

MMSE, IADL and SBI-bADL scores were all significantly correlated with folate concentrations (respectively: r = 0.36, r = -0.39, r = -0.35; p < 0.0001), while no significant associations were found with vitamin B(12) concentrations. When entered into multiple linear regression analyses with several covariates, folate showed a highly significant, curvilinear association with both cognitive and functional scores (p < 0.0001). Subjects in low and middle folate tertiles had significantly higher odds ratios for dementia (p < 0.0001; adjusted ORs = 5.40 and 6.56, lower 95% CIs 2.53 and 3.11, higher 95% CIs 12.73 and 15.29).

CONCLUSIONS

Findings of this population-based study suggest that subclinical folate deficiency may represent a risk factor for the cognitive decline associated with aging that could contribute to AD as well as other dementia development.

The Nutrition, Aging, and Memory in Elders (NAME) study: design and methods for a study of micronutrients and cognitive function in a homebound elderly population

BACKGROUND

Micronutrient status can affect cognitive function in the elderly; however, there is much to learn about the precise effects. Understanding mediating factors by which micronutrient status affects cognitive function would contribute to elders' quality of life and their ability to remain in the home.

OBJECTIVES

The Nutrition, Aging, and Memory in Elders (NAME) Study is designed to advance the current level of knowledge by investigating potential mediating factors by which micronutrient status contributes to cognitive impairment and central nervous system abnormalities in the elderly. NAME targets homebound elders because they are understudied and particularly at risk for poor nutritional status.

METHODS

Subjects are community-based elders aged 60 and older, recruited through area Aging Services Access Points. The NAME core data include demographics; neuropsychological testing and activities of daily living measures; food frequency, health and behavioral questionnaires; anthropometrics; gene status; plasma micronutrients, homocysteine, and other blood determinants. A neurological examination, psychiatric examination, and brain MRI and volumetric measurements are obtained from a sub-sample.

RESULTS

Preliminary data from first 300 subjects are reported. These data show that the NAME protocol is feasible and that the enrolled subjects are racially diverse, at-risk, and had similar basic demographics to the population from which they were drawn.

CONCLUSION

The goal of the NAME study is to evaluate novel relationships between nutritional factors and cognitive impairment. These data may provide important information on potential new therapeutic strategies and supplementation standards for the elderly to maintain cognitive function and potentially reduce the public health costs of dementia.

Plasma total homocysteine and memory in the elderly: the Hordaland Homocysteine Study

We examined the relation between plasma total homocysteine (tHcy), folate, vitamin B12, and episodic memory in elderly community-dwelling subjects. A population-based study was conducted in 1992 and 1993, and subjects were re-investigated after 6 years. Plasma analytes were determined on both occasions. At follow-up, memory performance, using the Kendrick Object Learning Test, was investigated in 2,189 subjects (age, 65-67 years at baseline). Subjects with memory deficit (test score, < 25) had higher tHcy and lower folate at follow-up compared with those without memory deficit: 12.6 (95% confidence interval [CI], 12.1, 13.1) versus 11.5 (95% CI, 11.3, 11.6) micromol/L (p < 0.001) for tHcy, and 6.7 (95% CI, 6.2, 7.1) versus 7.6 (95% CI, 7.5, 7.8) nmol/L (p < 0.001) for folate. The risk of memory deficit increased according to quintiles of tHcy both at baseline and at follow-up. A decline in tHcy, or an increase in folate, over a 6-year period was associated with a higher memory test score; and vice versa. These findings indicate that increased plasma tHcy is an independent risk factor for memory deficit both cross-sectionally and prospectively, and that a "favorable" change in folate or tHcy concentrations over time is associated with better memory performance.

Vitamin B12 and folate depletion: clinical evidence in a neurological population

In cross-sectional studies, low levels of folate and vitamin B12 have been associated with poor cognition and dementia. Results are quite controversial and a debate continues in the literature. Still not completely understood are the differential roles of folate and vitamin B12 in memory acquisition and cognitive development. More intriguing and not fully understood is the rule that treating a vitamin B12-deficient patient with folate may exacerbate the neurological consequences of either deficiency. Starting from these quite confusing perspectives, the aim of this study was to define a possible role of vitamin B12 and folate in cognitive disruption. Data were collected among a cohort of people, admitted to the Neurology Clinic of the University of Trieste, in a period between November 1,2000, and November 1, 2002. We examine potential risk factors, concomitant drug-therapies, and cognitive global performance and correlate these parameters with folate and vitamin B 12 serum levels.We discuss the results with an overview of the literature.

Cobalamin (vitamin B12) in subacute combined degeneration and beyond: traditional interpretations and novel theories

Subacute combined degeneration (SCD) is a neuropathy due to cobalamin (Cbl) (vitamin B(12)) deficiency acquired in adult age. Hitherto, the theories advanced to explain the pathogenesis of SCD have postulated a causal relationship between SCD lesions and the impairment of either or both of two Cbl-dependent reactions. We have identified a new experimental model, the totally gastrectomized rat, to reproduce the key morphological features of the disease [spongy vacuolation, intramyelinic and interstitial edema of the white matter of the central nervous system (CNS), and astrogliosis], and found new mechanisms responsible for the pathogenesis of SCD: the neuropathological lesions in TGX rats are not only due to mere vitamin withdrawal but also to the overproduction of the myelinolytic tumor necrosis factor (TNF)-alpha and the reduced synthesis of the two neurotrophic agents, epidermal growth factor (EGF) and interleukin-6. This deregulation of the balance between TNF-alpha and EGF synthesis induced by Cbl deficiency has been verified in the sera of patients with pernicious anemia (but not in those with iron-deficient anemia), and in the cerebrospinal fluid (CSF) of SCD patients. These new functions are not linked to the coenzyme functions of the vitamin, but it is still unknown whether they involve genetic or epigenetic mechanisms. Low Cbl levels have also been repeatedly observed in the sera and/or CSF of patients with Alzheimer's disease or multiple sclerosis, but whether Cbl deficit plays a role in the pathogenesis of these diseases is still unclear.

Neuropsychology of vitamin B12 deficiency in elderly dementia patients and control subjects

Cobalamin deficiency may cause cognitive deficits and even dementia. In Alzheimer's disease, the most frequent cause of dementia in elderly persons, low serum levels of vitamin B12, may be misleading. The aim of this work was to characterize the cognitive pattern of B12 deficiency and to compare it with that of Alzheimer's disease. Nineteen patients with low levels of vitamin B12 were neuropsychologically evaluated before treatment and a year later. Results were compared with those of 10 healthy control subjects. Final results suggest that there is a different pattern in both diseases. Twelve elderly patients with dementia improved with treatment. Seven elderly demented patients did not improve; they deteriorated after 1 year although their levels of cobalamin were normal. Analysis of the initial evaluation showed that the 2 groups of patients had a different neuropsychological profile. The group that improved had initially more psychotic problems and more deficits in concentration, visuospatial performance, and executive functions. They did not show language problems and ideomotor apraxia, which were present in the second group. Their memory pattern was also different. These findings suggest that cobalamin deficiency may cause a reversible dementia in elderly patients. This dementia may be differentiated from that of Alzheimer's disease by a thorough neuropsychological evaluation.

Homocysteine versus the vitamins folate, B6, and B12 as predictors of cognitive function and decline in older high-functioning adults: MacArthur Studies of Successful Aging

BACKGROUND

Elevated plasma total homocysteine concentration may be a risk factor for cognitive decline and Alzheimer disease, but data from prospective studies are limited. Further, high homocysteine levels are associated with low vitamin status, and it is unknown whether it is homocysteine toxicity or vitamin insufficiency that is responsible for the observed cognitive dysfunction.

METHODS

We performed cross-sectional and longitudinal analyses of a cohort of 499 high-functioning community-dwelling persons aged 70 to 79 years to determine the effect of homocysteine and related vitamin plasma concentrations on cognitive function and cognitive decline. Nonfasting plasma concentrations of homocysteine, folate, vitamin B(6), and vitamin B(12) were measured at baseline. Summary measures of cognitive function were created from tests of multiple cognitive domains administered at baseline and again after 7 years.

RESULTS

In cross-sectional analyses investigating each variable separately, subjects with elevated homocysteine levels, or low levels of folate or vitamin B(6), demonstrated worse baseline cognitive function. In longitudinal analyses, after adjusting for multiple covariates, including homocysteine, those in the bottom quartile of folate had a 1.6-fold increased risk (95% confidence interval: 1.01 to 2.31; P =0.04) of being in the worst quartile of 7-year cognitive decline. Low folate levels largely accounted for a trend towards greater cognitive decline with elevated homocysteine level.

CONCLUSION

In high-functioning older adults, low folate levels appear to be a risk factor for cognitive decline. The risk of developing cognitive decline might be reduced through dietary folate intake.

Plasma homocysteine, vitamin B12 and folate in Alzheimer's patients and healthy Arabs in Israel

High plasma homocysteine (tHcy) is a risk factor for cardiovascular disease and stroke and Alzheimer's disease (AD). An inverse relationship has been reported between tHcy and plasma B12 and folate levels. Seventy-nine AD patients and 156 controls from three Arab villages in northern Israel participated. Plasma tHcy, B12 and folate levels were determined. Data were analyzed using univariate statistical tests and logistical regression with confounders. tHcy was significantly higher in AD patients (20.6+/-8.7 micromol/l) than in controls (16.4+/-6.5 micromol/l) (p=0.03) after correction for year of birth, gender and smoking status. Plasma B12 (322.9+/-136.0/350.5+/-175.3 pmol/l) and plasma folate (4.5+/-3.8/4.9+/-2.6 nmol/l) levels did not differ significantly between AD patients and controls. Subjects in the highest tHcy tertile or in the lowest B12 and folate tertiles did not have greater risk to develop AD. In this population residing in Arab villages in northern Israel, tHcy levels were significantly higher among AD patients than in controls. Plasma B12 and folate levels were lower among cases but were not significant. There was not a significant association between plasma tHcy, B12 and folate levels in controls or AD patients. High levels of tHcy may suggest the need for folate and vitamin B12 supplementation in this population.

Dietary factors and Alzheimer's disease

Alzheimer's disease (AD) is increasing in prevalence, and environmental risk factors have not been identified with certainty. There is evidence that oxidative stress, homocysteine-related vitamins, fats, and alcohol have a role in the pathogenesis of AD. Few large epidemiological studies have explored the associations between nutrients and AD, and there has been only one trial of vitamin E in the prevention of AD. Some studies suggest that high intake of vitamins C, E, B6, and B12, and folate, unsaturated fatty acids, and fish are related to a low risk of AD, but reports are inconsistent. Modest to moderate alcohol intake, particularly wine, may be related to a low risk of AD. Available data do not permit definitive conclusions regarding diet and AD or specific recommendations on diet modification for the prevention of AD.

Nutritional factors and Alzheimer's disease

Nutritional factors are integrally linked with Alzheimer's disease (AD). Although AD patients have no changes in energy metabolism, fluctuations in weight are fairly common. The potential role of vitamin B(12) and folate, with the production of hyperhomocysteinemia, in the pathophysiology of AD is explored. The role of free-radical damage in AD is discussed. It is stressed that alterations in dietary lipids may play an important role in cognitive defects in AD secondary to their effects on neuronal membrane lipids. More research is needed on the role of nutrition in the ongoing development of cognitive changes in AD.

Nutrition and cognitive impairment in the elderly

As the number of older people is growing rapidly worldwide and the fact that elderly people are also apparently living longer, dementia, the most common cause of cognitive impairment is getting to be a greater public health problem. Nutrition plays a role in the ageing process, but there is still a lack of knowledge about nutrition-related risk factors in cognitive impairment. Research in this area has been intensive during the last decade, and results indicate that subclinical deficiency in essential nutrients (antioxidants such as vitamins C, E and beta-carotene, vitamin B(12), vitamin B(6), folate) and nutrition-related disorders, as hypercholesterolaemia, hypertriacylglycerolaemia, hypertension, and diabetes could be some of the nutrition-related risk factors, which can be present for a long time before cognitive impairment becomes evident. Large-scale clinical trials in high-risk populations are needed to determine whether lowering blood homocysteine levels reduces the risk of cognitive impairment and may delay the clinical onset of dementia and perhaps of Alzheimer's disease. A curative treatment of cognitive impairment, especially Alzheimer's disease, is currently impossible. Actual drug therapy, if started early enough, may slow down the progression of the disease. Longitudinal studies are required in order to establish the possible link of nutrient intake--nutritional status with cognitive impairment, and if it is possible, in fact, to inhibit or delay the onset of 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.

Subnormal serum vitamin B12 and behavioural and psychological symptoms in Alzheimer's disease

The objective of this study was to examine whether patients with Alzheimer's disease (AD) with subnormal vitamin B12 levels show more frequent behavioural and psychological symptoms of dementia (BPSD) than AD patients with normal vitamin B12 levels. The design was a prospective case-control study. The study took place at a memory-clinic of a department of geriatric medicine in a teaching hospital. There were seventy-three consecutive outpatients with probable AD, including 61 patients with normal and 12 patients with subnormal (<200 pg/ml) vitamin B12. BPSD were measured using the subscales disturbed behaviour and mood of the Nurses' Observation Scale for Geriatric Patients (NOSGER), the Cornell Scale for Depression and the four criteria for personality change in dementia from the International Classification of Diseases (ICD-10). Controlling for dementia duration and degree of severity of the cognitive deficits, there were significant inverse associations between vitamin B12 status and ICD-10 irritability (p=0.045) and NOSGER subscale disturbed behaviour (p=0.015). Low vitamin B12 serum levels are associated with BPSD in AD. Vitamin B12 could play a role in the pathogenesis of behavioural changes in AD.

Alzheimer disease: protective factors

Approximately 6-8% of all persons aged >65 y have Alzheimer disease and the prevalence of the disease is increasing. Any intervention strategy aimed at decreasing risks or delaying the onset of the disease will therefore have a substantial effect on health care costs. Nutrition seems to be one of the factors that may play a protective role in Alzheimer disease. Many studies suggest that oxidative stress and the accumulation of free radicals are involved in the pathophysiology of the disease. Several studies have shown the existence of a correlation between cognitive skills and the serum concentrations of folate, vitamin B-12, vitamin B-6, and, more recently, homocysteine. However, nutritional factors have to be studied not alone but with the other factors related to Alzheimer disease: genetics, estrogen, antiinflammatory drug use, and socioeconomic variables. The objective of this article was to review recent studies in this field.

Complementary and alternative medicines for Alzheimer's disease

The recent successes of large, multicenter clinical trials of acetylcholinesterase inhibitors for symptomatic treatment of Alzheimer's disease have spawned enthusiasm that this common and fatal neurologic disease is "treatable." A parallel explosion has occurred in the consumption of alternative medicines by the public seeking more effective, natural, or safer methods for treatment of dementia. Some of these medicines may, in fact, be biologically active in modulating the disease as well as producing side effects and interactions with accepted pharmaceuticals. This review brings to focus the scientific evidence presently available regarding such agents.

Associated physical disease in a demented population

Clinical experience indicates that physical diseases are probably underdiagnosed in patients suffering from dementia. We investigated the prevalence of physical diseases in patients with different types of dementia by means of a retrospective patient record survey including 236 inpatients and outpatients referred for dementia evaluation to the Dementia Investigation Unit, University Hospital in Linköping during 1994. Forty-four patients had dementia of the Alzheimer type, 78 had vascular dementia, 28 had dementia due to multiple etiologies, 42 were not demented, and 44 patients could not be classified by the DSM IV criteria. The physical diseases were registered as separate diagnoses comprising all newly-diagnosed physical diseases and previously known diseases that had exacerbated and contributed to the medical contact. Sixty-four percent of the patients had previously unknown physical diseases and/or exacerbation of previously known diseases. The most common physical conditions were cobalamin deficiency and infectious diseases, which occurred in 27% and 24% of the patients, respectively. There was no difference in the number or kinds of diagnoses between the diagnostic groups. Associated physical diseases were underdiagnosed in patients referred for dementia evaluation. We suggest that thorough medical investigation and adequate treatment are of importance in the management of dementia.

Folate and cobalamin in psychiatric illness

The linkage of cobalamin and folate deficiency to psychiatric illness has been studied and debated since these vitamins were first discovered in the 1940s. The clinical relevance of these deficiencies remains the subject of investigation and scholarly discussion. This article reviews case reports and studies derived from a MEDLINE search for English-language articles related to folate, cobalamin, and psychiatric illness. Emphasis is given to clinical research and recent developments. Preclinical evidence for direct effects of folate and cobalamin on brain functioning is compelling, and numerous associations of their deficiencies to psychiatric illness are evident. These vitamin deficiencies may typically present initially with psychiatric symptoms, but any direct causal relationship to specific neuropsychiatric illnesses are not well defined. The relationship of these vitamins in dementia is significant, but they may only rarely be a cause of truly reversible dementia. Folate deficiency appears most tightly connected with depressive disorders, and cobalamin deficiency with psychosis. Contrary to intuition, vitamin deficiencies appear to occur infrequently with eating disorders. Other diagnoses have been investigated much less extensively. The diagnosis and management of these deficiencies in the context of neuropsychiatric illness is still a matter of discussion. The quality of clinical research in this area is improving, but there are many unanswered questions that affect clinical practice. Clinicians should remain vigilant to the possibility of deficiencies of folate and cobalamin in diverse psychiatric populations. Normal hematological indices do not rule out the deficiencies. Further study is needed to refine the detection and clinical management of these vitamin deficiencies in psychiatric populations.

Prevalence and haemopoietic effects of low serum vitamin B12 levels in geriatric medical patients

The clinical significance of low serum vitamin B12 levels in elderly people is controversial. We aimed to document the prevalence of a low serum vitamin B12 (< 175 pmol/l) in patients referred to a geriatric medical unit, and to determine whether haemopoiesis is commonly affected in elderly patients with low serum vitamin B12. We studied prospectively 472 consecutive referrals to a geriatric medical unit; fifty-six (13%) had a low serum vitamin B12 level, of whom nineteen (34%) of the fifty-six also had evidence of Fe deficiency (serum ferritin < 45 ng/ml). Low vitamin B12 was associated with a raised mean erythrocyte volume (MCV; mean 96.0 (SD 6.7) fl), compared with a control group (91.7 (SD 6.0) fl; P = 0.001). However, only thirteen (23%) of the fifty-six patients with a low vitamin B12 had an MCV > or = 100 fl. Mean haemoglobin (Hb) levels were not significantly reduced in those with a low vitamin B12. In a subsequent study the haematological response to intramuscular hydroxocobalamin was examined in thirty-four patients with a low serum vitamin B12. Treatment resulted in a significant fall in MCV and rise in Hb; these effects could be detected both in those patients with an initially normal full blood count (change in MCV -1.2 (SD 1.2); Hb +0.5 (SD 0.6); P < 0.01) and in those with macrocytosis and/or anaemia (-9.1 (SD 11.8); +0.8 (SD 1.2); P < 0.05). A low serum vitamin B12 is common in geriatric medical patients. This is usually associated with an upset in erythropoiesis, although the abnormalities are often subtle and may not be apparent on inspection of the full blood count. Elderly patients with serum vitamin B12 < 175 pmol/l should be assumed to have vitamin deficiency even if their full blood count is normal.

Risk of Alzheimer's disease among elderly patients with anemia: population-based investigations in Olmsted County, Minnesota

PURPOSE

To evaluate the association, if any, between Alzheimer's disease (AD) and anemia among the elderly.

METHODS

Both case-control and cohort methodologies were used to evaluate this association. The case-control study included all incident cases of AD whose onset occurred during 1980-1984 in Rochester, MN (n = 302). An age- and gender-matched control was selected from among Rochester residents seen for care at Mayo Clinic during the year of onset of the case. All community medical records for cases and controls were reviewed to identify women with hemoglobin levels of < 12 g/dL and men with hemoglobin levels of < 13 g/dL during the year of onset and the prior year for cases and during the index year and year prior for controls. Logistic regression was used to estimate odds ratios (OR). The retrospective cohort study used the 618 residents of Olmsted County, MN, who were > or = 65 years of age and whose anemia, as defined above, was newly recognized in 1986. Standardized incidence ratios (SIR) for AD were estimated by use of the person-years of follow-up in the cohort and the incidence rates of AD for this community.

RESULTS

In the case-control study, an almost twofold increase in occurrence of AD was associated with anemia (OR, 1.88; 95% CI, 1.17-3.03). For men and women, respectively, the ORs were 1.81 (95% CI, 0.75-4.39) and 1.96 (95% CI, 1.11-3.47). The cohort study showed no overall increase in risk of AD (SIR, 0.98; 95% CI, 0.67-1.37). For men, the SIR was a comparable 1.49 (95% CI, 0.79-2.56), whereas for women the SIR was only 0.79 (95% CI, 0.49-1.23).

CONCLUSIONS

Although anemia may be a risk factor for AD in the elderly, the mechanism by which anemia contributes to the pathogenesis of AD or to the unmasking of AD symptoms is unknown.

Circadian variation of plasma cobalamin, transcobalamin-bound cobalamin and unsaturated binding capacity of transcobalamin and haptocorrin in healthy elderly

Blood samples were drawn every second hour during a 24-h period from healthy elderly subjects. Plasma levels of cobalamin, albumin, transcobalamin-bound cobalamin and unsaturated binding capacity of transcobalamin and haptocorrin were determined. During night, all components decreased in parallel with plasma albumin. The nocturnal decreases were therefore ascribed to plasma volume changes due to bed-rest. Reports on the recently proposed role of cobalamin for the biological clock were reviewed, but the proposed role could not be explained by this study.

Cobalamin and folate deficiency in the elderly

Elderly persons are more likely to have low values for serum and erythrocyte folate, and for serum cobalamin. Many of those with low vitamin levels have biochemical abnormalities consistent with true deficiency, including increased formiminoglutamic acid excretion, abnormal marrow deoxyuridine suppression, and raised serum levels of methylmalonic acid and homocysteine. Therapy with the appropriate vitamin reverses the biochemical defect. Despite this, the clinical consequences for most elderly persons are remarkably few. True megaloblastic anaemia is rare, and the small number of therapeutic trials to date have not improved the levels of haemoglobin in the treated subjects, although the mean corpuscular volume has decreased significantly. There has been recent concern that these low blood vitamin levels might be important causes of nervous system damage, but studies specifically of the elderly have not demonstrated overall improvements in neurological function following therapy. Vascular damage from high blood homocysteine levels secondary to cobalamin or folate deficiency remains a potential hazard. Dietary insufficiency, malabsorption of protein-bound vitamin B12 secondary to atrophic gastritis, and defective absorption of folyl polyglutamates seem the likeliest possible causes. Pernicious anaemia, although a common cause of severe megaloblastic anaemia in the elderly, is an infrequent cause for the low cobalamin levels in population studies. Although the benefits are uncertain, the balance of the evidence suggests that one should treat elderly persons with low values of cobalamin or folate. Crystalline vitamin B12 and folic acid are absorbed normally and are therefore suitable for replacement therapy, provided that pernicious anaemia is excluded.