Association Between Homocysteine and Vitamin Levels in Demented Patients

From Gut to Brain: Uncovering Potential Serum Biomarkers Connecting Inflammatory Bowel Diseases to Neurodegenerative Diseases

Inflammatory bowel diseases (IBDs) are characterized by chronic gastrointestinal inflammation due to abnormal immune responses to gut microflora. The gut-brain axis is disrupted in IBDs, leading to neurobiological imbalances and affective symptoms. Systemic inflammation in IBDs affects the brain's inflammatory response system, hormonal axis, and blood-brain barrier integrity, influencing the gut microbiota. This review aims to explore the association between dysregulations in the gut-brain axis, serum biomarkers, and the development of cognitive disorders. Studies suggest a potential association between IBDs and the development of neurodegeneration. The mechanisms include systemic inflammation, nutritional deficiency, GBA dysfunction, and the effect of genetics and comorbidities. The objective is to identify potential correlations and propose future research directions to understand the impact of altered microbiomes and intestinal barrier functions on neurodegeneration. Serum levels of vitamins, inflammatory and neuronal damage biomarkers, and neuronal growth factors have been investigated for their potential to predict the development of neurodegenerative diseases, but current results are inconclusive and require more studies.

A micronutrient supplement modulates homocysteine levels regardless of vitamin B biostatus in elderly subjects

Elevated homocysteine (Hcy) levels (≥15 μmol/L) in the elderly are frequently associated with a higher risk of cardiovascular disease and cognitive decline. Several studies have already shown an Hcy-lowering effect of B vitamin supplementation in cohorts deficient in these nutrients. The aim of this randomized, double-blinded 12-week intervention study was to investigate whether Hcy levels in healthy elderly subjects (75.4±4.5 years, n=133) could be lowered with a micronutrient supplement (i.e., 400 μg folic acid, 100 μg cobalamin). Difference in mean initial Hcy levels between intervention (17.6±7.1 μmol/L, n=65) and placebo group (18.9±6.1 μmol/L, n=68) was not significant. The prevalence of cobalamin and folate deficiency in the total study population was low: 27% had serum-cobalamin levels ≤150 pmol/L, 12% holo-transcobalamin (Holo-TC) levels ≤50 pmol/L, 13% low cobalamin status using the aggregated cobalamin marker 4cB12 and 10% red blood cell (RBC) folate ≤570 nmol/L. Nevertheless, the treated subjects still showed improved cobalamin and folate biostatus (serum cobalamin Δt12-t0: 63±48 pmol/L; Holo-TC Δt12-t0: 17±19 pmol/L; RBC folate Δt12-t0: 326±253 nmol/L) and Hcy levels (Δt12-t0: -3.6±5.7 μmol/L). The effects were statistically significant compared to the placebo group with p=0.005 (serum cobalamin), p=0.021 (Holo-TC), p=0.014 (RBC-folate) and p<0.001 (Hcy). The Hcy-lowering effect was dependent on the initial Hcy levels (p<0.001). Our findings suggest that elevated Hcy levels in elderly subjects can be lowered regardless of the initial cobalamin and folate biostatus.

Prevalence of nutrition disorders and nutrition-related conditions in older patients with Alzheimer's disease

BACKGROUNDS

Alzheimer's disease is frequently encountered with nutrition-related conditions such as malnutrition, sarcopenia, frailty, overnutrition, and micronutrient abnormalities in older patients. In this study, we aimed to evaluate the prevalence of nutrition disorders and nutrition-related conditions in the same patient group.

METHODS

A total of 253 older patients with Alzheimer's disease underwent comprehensive geriatric assessment, which included nutrition-related disorders, malnutrition via the Mini Nutritional Assessment-Short Form (MNA-SF), frailty via the Clinical Frailty Scale (CFS), and sarcopenia was diagnosed according to European Working Group on Sarcopenia in Older People-2 criteria.

RESULTS

The patients' mean age was 79.8 ± 6.5 years, and 58.1% were women. In our patients, 64.8% had malnutrition or were at risk of malnutrition; 38.3% had sarcopenia; 19.8% were prefrail; and 80.2% were frail. Malnutrition, frailty, and sarcopenia prevalence increased as the Alzheimer's disease stage progressed. Malnutrition was found to be significantly related with frailty scores via CFS (odds ratio [OR], 1.397; P = 0.0049) and muscle mass via fat-free mass index (FFMI) (OR, 0.793; P = 0.001). In logistic regression analysis, age, MNA-SF, and CFS were included in the model to detect the independent correlates of probable and confirmed sarcopenia. CFS was independently associated with probable and confirmed sarcopenia (OR, 1.822; P = 0.013; OR, 2.671; P = 0.001, respectively). Frailty was similarly related with FFMI (OR, 0.836; P = 0.031). Obesity was independently related with FFMI (OR, 0.688; P < 0.001).

CONCLUSION

In conclusion, nutrition disorders and nutrition-related conditions can present concurrently in patients with all stages of Alzheimer's disease; therefore, these frequent problems should be screened and diagnosed accordingly.

Serum Homocysteine, Vitamin B12, Folate, and Their Association with Mild Cognitive Impairment and Subtypes of Dementia

BACKGROUND

Although elevated levels of homocysteine (Hcy) are associated with cognitive impairment and dementia, the relevance of Hcy, vitamin B12, and folate levels to subtypes of dementia are still unknown.

OBJECTIVE

To investigate the changes of Hcy, vitamin B12, and folate levels in mild cognitive impairment (MCI) and subtypes of dementia including Alzheimer's disease (AD), vascular dementia (VaD), frontotemporal dementia (FTD), and Lewy body dementia (LBD), and their relationships with cognitive function and magnetic resonance imaging (MRI) markers.

METHODS

We measured serum levels of Hcy, vitamin B12, and folate in 257 subjects. Each subject underwent cognitive function assessment and brain MRI test. The Fazekas and temporal lobe atrophy (MTA) visual rating scales were used to assess the degree of white matter hyperintensities and MTA, respectively.

RESULTS

Serum levels of Hcy was higher and vitamin B12 was lower in AD, VaD, FTD, and LBD groups than cognitively normal controls. No significant differences of folate levels were found among 6 groups. Hcy levels were positively correlated with MTA total score in AD (r = 0.448, p < 0.001). Vitamin B12 levels were positively correlated with MoCA in VaD (r = 0.497), and negatively correlated with MTA total score in AD (r = - 0.325) (ps < 0.05). Hyperhomocysteinemia may increase the risk of AD (OR = 2.744), VaD (OR = 3.600), and FTD (OR = 3.244) in the adjusted model (ps < 0.05).

CONCLUSION

Hcy and vitamin B12 levels are associated with MTA in AD. Vitamin B12 levels are associated with general cognition in VaD. Hyperhomocysteinemia is a risk factor for not only AD and VaD but also FTD.

Homocysteine, Cognitive Functions, and Degenerative Dementias: State of the Art

There is strong evidence that homocysteine is a risk factor not only for cerebrovascular diseases but also for degenerative dementias. A recent consensus statement renewed the importance and the role of high levels of homocysteine in cognitive decline in several forms of degenerative dementia, such as Alzheimer's disease. Although the molecular mechanisms by which homocysteine causes cell dysfunction are known, both the impact of homocysteine on specific cognitive functions and the relationship between homocysteine level and non-Alzheimer dementias have been poorly investigated. Most of the studies addressing the impact of hyperhomocysteinemia on dementias have not examined the profile of performance across different cognitive domains, and have only relied on screening tests, which provide a very general and coarse-grained picture of the cognitive status of the patients. Yet, trying to understand whether hyperhomocysteinemia is associated with the impairment of specific cognitive functions would be crucial, as it would be, in parallel, learning whether some brain circuits are particularly susceptible to the damage caused by hyperhomocysteinemia. These steps would allow one to (i) understand the actual role of homocysteine in the pathogenesis of cognitive decline and (ii) improve the diagnostic accuracy, differential diagnosis and prognostic implications. This review is aimed at exploring and revising the state of the art of these two strictly related domains. Suggestions for future research are provided.

Unveiling of dietary and gut-microbiota derived B vitamins: Metabolism patterns and their synergistic functions in gut-brain homeostasis

Nutrition-gut cross-talk holds a vital position in sustaining intestinal function, and micronutrient metabolism has emerged as the foremost metabolic pathway to preserve gut homeostasis. Among micronutrients, B vitamins have evolved prior to DNA/RNA and are known for their vital roles for major evolutionary transitions in extant organisms. Despite their universal requirement and critical role, not all the three domains of life are endowed with a natural ability for de novo B vitamins synthesis. The human gut microbiome constitutes prototrophs and auxotroph which are entirely dependent on dietary intake and gut microbial production of B vitamins. The syntrophic metabolism involving cross-feeding of B vitamins and community-wide exchange between commensal bacteria elicit important changes in the diversity and composition of the human gut microbiome. Hereto, we discuss the B-vitamins sharing among prototrophic and auxotrophic gut bacteria, their absorption in small intestine and transport in distal gut, functional role in relation to the gut homeostasis and symptoms linked to their deficiency. We also briefly explore their potential involvement as psychobiotics in brain energetic metabolism (kynurenines/tryptophan pathway) for neurological functions and highlight their deficiency related malfunctioning.

Association Between Blood Biochemical Factors Contributing to Cognitive Decline and B Vitamins in Patients With Alzheimer's Disease

Background

Malnutrition, metabolism stress, inflammation, peripheral organs dysfunction, and B vitamins deficiency significantly contribute to the progression and mortality of Alzheimer's disease (AD). However, it is unclear which blood biochemical indicators are most closely related to cognitive decline and B vitamins deficiency (thiamine, folate, vitamin B12) in patients with AD.

Methods

This was a cross-sectional study of 206 AD patients recruited from six hospitals in China. Thiamine diphosphate (TDP), the bioactive form of thiamine, was measured by high-performance liquid chromatography fluoroscopy (HPLC) at a single center. Levels of biochemical indicators (except TDP) were measured by regular and standard laboratory tests in each hospital. Pearson's rank correlation analysis was used to assess relationships between B vitamins and biochemical indicators. T-test was used to compare the difference between ApoE ε4 and non-ApoE ε4 groups. Differences were considered statistically significant as P < 0.05.

Results

Among the biochemical results, in AD population, malnutrition indicators (erythrocyte, hemoglobin, serum albumin, and total protein) were most significantly associated with cognitive function, as was free triiodothyronine (FT3) levels which had been observed in previous study. Malnutrition and FT3 levels depend on age but not apolipoprotein E (ApoE) genotype. Meanwhile, Among the B vitamins, TDP was the most significantly associated with malnutrition indicators and FT3.

Conclusion

Our results indicated that TDP reduction could be a modifiable risk factor for malnutrition and FT3 that contributed to cognitive decline in AD patients. Correcting thiamine metabolism could serve as an optional therapy target for AD treatment.

Association of Elevated Plasma Total Homocysteine With Dementia With Lewy Bodies: A Case-Control Study

Background: Elevated plasma total homocysteine (tHcy) level, a known risk factor for vascular disease, is reported to be an independent risk factor for cognitive impairment and Alzheimer’s disease (AD) in most studies. tHcy may also be associated with dementia with Lewy bodies (DLB).

Objective: To investigate the association between plasma tHcy levels and DLB or AD.

Methods: This is a case-control study including 132 DLB patients, 264 AD patients, and 295 age-matched healthy controls. We used multivariate logistic regression model to analyze the data with adjustments for confounding variables.

Results: The highest tHcy tertile (>13.9 μmol/L) was significantly independently associated with DLB [adjusted odds ratio (OR): 4.65, 95% confidence interval (CI): 1.95–11.10, P = 0.001] and AD (adjusted OR: 1.82, 95% CI: 1.02–3.23, P = 0.041) compared to the lowest tertile (<10.7 μmol/L). The cumulative frequency plots showed a shift in the distribution of the tHcy concentrations to higher values in patients with DLB compared to AD. The mean tHcy levels were stable and not altered by the duration of cognitive impairment prior to the collection of blood samples from DLB patients.

Conclusion: Elevated plasma tHcy levels were independently associated with DLB, and the association was stronger for DLB than for AD. The lack of a relationship between tHcy levels and symptom duration may refute these observed associations being a consequence of DLB, and future longitudinal studies will be required to confirm whether tHcy plays a causative role in DLB.