Do MCI patients with vitamin B12 deficiency have distinctive cognitive deficits?

Comparison of homocysteine, vitamin B12 and folic acid between rural and urban ageing Indians and its association with mild cognitive impairment and cardiovascular risk factors: a cross-sectional analysis

The relationship between blood levels of homocysteine (HCY), vitamin B12, folic acid and cognitive impairment is inconclusive. Since HCY is an independent risk factor for cardiovascular diseases, understanding its association with Framingham risk score (FRS) may provide insight into the shared underlying mechanism between cardiovascular disease and cognitive impairment. Cross-sectional analyses utilized baseline data from two ongoing longitudinal studies: the Tata Longitudinal Study of Ageing (n = 923), an urban cohort, and Srinivaspura Ageing, NeuroSenescence and COGnition (n = 4239), a rural cohort. The study compared the HCY, vitamin B12 and folic acid levels across cohorts and normal versus mild cognitive impairment (MCI) participants. The association between HCY and cognitive status was established using regression models. Three models were analysed: model 1-unadjusted; model 2-adjusted for age, gender, smoking, alcohol consumption, diet, hypertension, cardiac illness, diabetes; and model 3-adjusted for variables in model 2 plus vitamin B12 and folic acid. Correlation was calculated between HCY and FRS. The urban cohort exhibited a significantly higher level of HCY [median (IQR) (17.70 (10.2) versus 14.70 (9.7); P < 0.001)], vitamin B12 (251 (231) versus 219 (138); P < 0.001) and folic acid (8.21 (8) versus 5.48 (4); P < 0.001) levels compared to rural cohort. HCY, vitamin B12 and folic acid levels did not differ significantly between normal and MCI participants in the urban cohort. In the rural cohort, among the age-gender matched MCI-normal, participants with normal cognition had higher levels of vitamin B12 (≥60 years) [227 (152) versus 217 (175); P = 0.03] and folic acid (<60 years) [5.91 (4) versus 5.40 (4); P = 0.04] compared to MCI. There was no association between HCY and cognitive status in both the cohorts, but there was a significant positive relationship between vitamin B12 deficiency and Clinical Dementia Rating-Sum of the Boxes (CDR-SOB), as well as folic acid deficiency and CDR-SOB in rural and urban cohorts, respectively, within a specific age group. A significant correlation was observed between FRS and HCY in the rural cohort (r = 0.17, P < 0.001), but not in the urban cohort. This study revealed significant differences in HCY, vitamin B12 and folic acid levels between the cohorts. In the rural cohort, participants with MCI had lower vitamin B12 and folic acid levels in a certain age group. Association between HCY and cognitive status was insignificant in both the cohorts. A small significant correlation between FRS and HCY was seen in the rural cohort.

Neuropsychiatric manifestations in vitamin B12 deficiency

Vitamin B12 deficiency can have distressing neuropsychiatric symptoms. It can have an etiological role in clinical presentations like depression, anxiety, psychosis, dementia, and delirium, requiring screening of at-risk populations. Few mechanisms that underlie the neuropsychiatric manifestations of B12 deficiency include alteration in one-carbon metabolism, genetic vulnerability, and alteration in folate metabolism. Maintaining a high serum B12 level in elderly can be protective against Alzheimer's disease (AD). In an established AD, its deficiency is associated with higher cognitive decline and risk for delirium. The other mental changes associated with B12 deficiency include apathy, agitation, impaired concentration, insomnia, persecutory delusions, auditory and visual hallucinations, and disorganized thought-process. Besides serum vitamin B12, plasma methylmalonic acid (MMA) and homocysteine helps in diagnosis. The chapter focuses on early recognition and effective treatment of these neuropsychiatric manifestations of vitamin B12 deficiency.

Vitamin B12, B6, or Folate and Cognitive Function in Community-Dwelling Older Adults: A Systematic Review and Meta-Analysis

BACKGROUND

Previous studies have indicated that B vitamin deficiencies are an essential cause of neurological pathology. There is a need to provide evidence of the benefit of B vitamins for the prevention of cognitive decline in community-dwelling older adults.

OBJECTIVE

To examine the association between intake and plasma levels of vitamins B12, B6, and folate and cognitive function in older populations through a systematic review and meta-analysis.

METHODS

Medline (PubMed), EMBASE, and Cochrane databases were used to search the literature though August 8, 2019. We included observational population-based studies evaluating the association between concentrations or intake levels of vitamins B6, B12, or folate and cognition in older adults aged ≥45 years. The quality of all studies was assessed by the modified Newcastle-Ottawa Scale. Odds ratios (ORs) and hazard ratios (HRs) were analyzed by the random-effects model. Sensitivity analyses were conducted by excluding the studies with significant heterogeneity.

RESULTS

Twenty-one observational studies with sample sizes ranging from 155-7030 were included in the meta-analysis. Higher levels of vitamin B12 (OR = 0.77, 95% CI = 0.61-0.97) and folate concentration (OR = 0.68, 95% CI = 0.51-0.90) were associated with better cognition in cross-sectional studies, but not in sensitivity analyses or prospective studies. High vitamin B6 concentrations showed no significant benefit on cognition and dementia risk. Prospective studies did not provide substantial evidence for the relationship.

CONCLUSION

The results from our meta-analysis suggest that vitamins B12, B6, and folate may not be modifiable risk factors for slowing cognitive decline among community-dwelling older individuals.

[Folic acid and vitamin B12 determination in the assessment of cognitive disorders : Overview and data analysis from a university outpatient memory clinic]

Vitamin B12 and folic acid deficiencies are particularly frequent conditions in older people. Since these metabolic disorders represent relevant dyscognitive factors, the assessment of vitamin B12 and folic acid levels is essential in the diagnostic approach of cognitive disorders, such as mild cognitive impairment and dementia in an outpatient memory clinic. This article summarizes the relevant diagnostic and therapeutic aspects of vitamin B12 and folic acid deficiencies and their effects on cognition. The literature review is supplemented by a data analysis of a naturalistic cohort of 250 patients from this outpatient memory clinic.

[Vitamin B12 deficiency in the elderly]

The prevalence of vitamin B12 deficiency increases with age. Patients with dementia and spouses of patients with dementia are at special risk for the development of vitamin B12 deficiency. In a normal diet this vitamin is present only in animal source foods; therefore, vegans frequently develop vitamin B12 deficiency if not using supplements or foods fortified with cobalamin. Apart from dementia, most of these manifestations are completely reversible under correct therapy; therefore it is crucial to identify and to treat even atypical presentations of vitamin B12 deficiency as early as possible. This article deals with the physiology and pathophysiology of vitamin B12 metabolism. A practice-oriented algorithm which also considers health economic aspects for a rational laboratory diagnosis of vitamin B12 deficiency is presented. In cases with severe neurological symptoms, therapy should be parenteral, especially initially. For parenteral treatment, hydroxocobalamin is the drug of choice.