Homocysteine, antioxidant micronutrients and late onset dementia

The Relationship between Whole-Grain Intake and Measures of Cognitive Decline, Mood, and Anxiety-A Systematic Review

Greater intake of whole grains, compared to refined grains, is consistently associated with a reduced risk of cardiovascular disease and type 2 diabetes, both of which are associated with cognitive decline. To better understand the relationship between whole-grain intake, cognition, mood, and anxiety, a systematic review was conducted to synthesize available evidence linking whole grains to these outcomes. Four electronic databases were searched from inception to August 2021 for potentially relevant observational and interventional studies. Risk of bias (RoB) assessments were performed using the newly developed Nutrition Quality Evaluation Strengthening Tools, and the Grades of Recommendation, Assessment, Development, and Evaluation approach was used to determine the strength of evidence for each outcome. In total, 23 studies [4 randomized controlled trials (RCTs) and 19 observational studies] met the predefined eligibility criteria. Of these,12 studies included analysis of whole-grain intake and cognitive decline, 9 included mood outcomes, and 2 included both cognition and mood outcomes. The overall evidence for an association between whole-grain intake and cognition is inconclusive. With respect to mood outcomes, evidence from RCTs prospective cohort and case-control studies suggest that higher intake is linked to improved outcomes for mood and depression although the evidence is mixed for cross-sectional studies. Reporting of whole-grain intake fell short of suggested standards, and the strength of available evidence was low or very low for all outcomes. A high RoB toward studies reporting results was also noted, complicating both the interpretation of some studies and the combined evidence. Of note, few well-designed RCTs assessing the effect of whole-grain intake on measures of cognition, mood, and anxiety were identified, highlighting the need for more studies in this area. The available, although limited, evidence suggests that greater whole-grain intake is associated with better mood and anxiety-related scores and is inconclusive regarding cognitive outcomes. PROSPERO registration: CRD42021266355.

Usual Intake of Micronutrients and Prevalence of Inadequate Intake among Chinese Adults: Data from CNHS 2015-2017

Previous studies have used the traditional average-value method to calculate the usual dietary intake of a population, but the results may be biased due to the measurement errors. The aim of this study was to provide an assessment of the usual micronutrient intake and estimate the prevalence of inadequate intake among Chinese adults. Data from the Chinese Nutrition and Health Surveillance 2015−2017 as well as a total of 72,231 subjects aged 18 years and older were included in the analysis. The 24 h recall method combined with the condiment weighing method were used for three consecutive days to collect daily food and condiments intake. The daily intake of 16 micronutrients was calculated based on the Chinese Food Component Tables. The National Cancer Institute (NCI) method was used to estimate the usual intake of micronutrients, and the prevalence of inadequate intake was estimated using the estimated average requirement (EAR) cut-point method. The results showed that, except for sodium, copper, iron (only for males), vitamin E, and phosphorus, the usual intake of micronutrients in Chinese adults was low, and the prevalence of inadequate intake ranged from 38.67 to 97.63%. The prevalence of inadequate calcium and riboflavin intake was more than 90%, and the proportion of individuals with a usual intake of thiamine, vitamin A, potassium, and selenium below EAR also reached 80%. Manganese, magnesium, vitamin C, and zinc were potentially deficient micronutrients, with the prevalence of inadequate intake ranging from 38.67% to 77.09%. However, usual sodium intake was extremely high with an average of 5139.61 mg/day, and only a quarter of Chinese adults were below the World Health Organization (WHO) recommended value. For most micronutrients, the usual dietary intake declined with age and the prevalence of inadequate intake increased with age. Except for zinc, vitamin A, and B-vitamins, the prevalence of micronutrient deficiencies was higher in females than in males in the same age group (p < 0.05). Therefore, Chinese adults do not receive enough micronutrients. Effective nutrition supplementary strategies and measures are needed to address these problems.

B vitamins and prevention of cognitive decline and incident dementia: a systematic review and meta-analysis

CONTEXT

Elevation of homocysteine (Hcy) levels is well-established as a risk factor for dementia, yet controversy exists regarding whether B-vitamin-mediated reduction of homocysteine levels can benefit cognitive function.

OBJECTIVE

To investigate whether B vitamin supplementation can reduce the risk of cognitive decline and incident dementia.

DATA SOURCES

The PubMed, EMBASE, Cochrane Library, and Web of Science were systematically searched for articles published from the inception dates to March 1, 2020. Randomized controlled trials (RCT) were included if B vitamins were supplied to investigate their effect on the rate of cognitive decline. Cohort studies investigating dietary intake of B vitamins and the risk of incident dementia were eligible. Cross-sectional studies comparing differences in levels of B vitamins and Hcy were included.

DATA EXTRACTION

Two reviewers independently performed data extraction and assessed the study quality.

DATA ANALYSIS

Random-effect or fixed-effect models, depending on the degree of heterogeneity, were performed to calculate mean differences (MDs), hazard ratios (HRs), and odds ratios (ORs).

RESULTS

A total of 95 studies with 46175 participants (25 RCTs, 20 cohort studies, and 50 cross-sectional studies) were included in this meta-analysis. This meta-analysis supports that B vitamins can benefit cognitive function as measured by Mini-Mental State Examination score changes (6155 participants; MD, 0.14, 95%CI 0.04 to 0.23), and this result was also significant in studies where placebo groups developed cognitive decline (4211 participants; MD, 0.16, 95%CI 0.05 to 0.26), suggesting that B vitamins slow cognitive decline. For the > 12 months interventional period stratum, B vitamin supplementation decreased cognitive decline (3814 participants; MD, 0.15, 95%CI 0.05 to 0.26) compared to placebo; no such outcome was detected for the shorter interventional stratum (806 participants; MD, 0.18, 95%CI -0.25 to 0.61). In the non-dementia population, B vitamin supplementation slowed cognitive decline (3431 participants; MD, 0.15, 95%CI 0.04 to 0.25) compared to placebo; this outcome was not found for the dementia population (642 participants; MD, 0.20, 95%CI -0.35 to 0.75). Lower folate levels (but not B12 or B6 deficiency) and higher Hcy levels were significantly associated with higher risks of dementia (folate: 6654 participants; OR, 1.76, 95%CI 1.24 to 2.50; Hcy: 12665 participants; OR, 2.09, 95%CI 1.60 to 2.74) and cognitive decline (folate: 4336 participants; OR, 1.26, 95%CI 1.02 to 1.55; Hcy: 6149 participants; OR, 1.19, 95%CI 1.05 to 1.34). Among the population without dementia aged 50 years and above, the risk of incident dementia was significantly decreased among individuals with higher intake of folate (13529 participants; HR, 0.61, 95%CI 0.47 to 0.78), whereas higher intake of B12 or B6 was not associated with lower dementia risk.

CONCLUSIONS

This meta-analysis suggests that B vitamin supplementation is associated with slowing of cognitive decline, especially in populations who received early intervention and intervention of long duration; the study also indicates that higher intake of dietary folate, but not B12 or B6, is associated with a reduced risk of incident dementia in non-dementia aged population. Given the prevalence of dementia cases in many countries with aging populations, public health policies should be introduced to ensure that subgroups of the population at risk have an adequate B vitamin status.

Relationship of Homocysteine Plasma Levels with Mild Cognitive Impairment, Alzheimer's Disease, Vascular Dementia, Psychobehavioral, and Functional Complications

Background:

Alzheimer’s disease (AD) may be a vascular disorder with neurodegenerative consequences opening possibility of preventing AD by targeting vascular risk factors including homocysteine.

Objective:

The study aims were to assess homocysteine distribution in different forms and severity of cognitive impairment (CogI) [mild cognitive impairment (MCI), probable AD (Prob-AD), possible AD (Poss-AD), and vascular dementia (VaD)] and in NoCogI, and to estimate possible association between hyperhomocysteinemia levels with functional deficit severity and psychobehavioral complications.

Methods:

In total, 929 (M = 366, F = 563; mean age of 72.55±6.24 years) patients were evaluated with cognitive, neuropsychiatric, affective, and functional assessment scales. Homocysteine serum was set on two levels: between 0 and 10μmol/L and > 10μmol/L. For each patient, blood concentration of folate, vitamin B12, hemoglobin, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), cholesterol, triglycerides, and glycemia were measured.

Results:

CogI patients demonstrated significantly a higher frequency of homocysteine > 10 (p = 0.003), than NoCogI patients. Patients with moderate and severe dementia had a higher frequency of homocysteine > 10 (p < 0.0001), than MCI and mild dementia. Poss-AD and VaD had a higher frequency of homocysteine > 10 (p = 0.003), than Prob-AD patients. Homocysteine > 10 frequency is directly proportional to increased neuropsychiatric symptom severity (p < 0.0001), and functional impairment severity respectively for ADL (p < 0.0001) and IADL (p < 0.0001).

Conclusion:

Higher homocysteine level seems to be significantly related to cognitive impairment frequency and severity, possible AD and VaD, neuropsychiatric symptom severity, and functional impairment severity.

Adherence to dietary guidelines and cognitive decline from middle age: the Doetinchem Cohort Study

BACKGROUND

Diet, in particular the Mediterranean diet, has been associated with better cognitive function and less cognitive decline in older populations.

OBJECTIVES

To quantify associations of a healthy diet, defined by adherence to either the Mediterranean diet, the WHO guidelines, or Dutch Health Council dietary guidelines, with cognitive function and cognitive decline from middle age into old age.

METHODS

From the Doetinchem Cohort Study, a large population-based longitudinal study, 3644 participants (51% females) aged 45-75 y at baseline, were included. Global cognitive function, memory, processing speed, and cognitive flexibility were assessed at 5-y time intervals up to 20-y follow-up. Adherence to the Mediterranean diet was measured with the modified Mediterranean Diet Score (mMDS), adherence to the WHO dietary guidelines with the Healthy Diet Indicator (HDI), and adherence to the Dutch Health Council dietary guidelines 2015 with the modified Dutch Healthy Diet 2015 index (mDHD15-index). The scores on the dietary indices were classified in tertiles (low, medium, high adherence). Linear mixed models were used to model level and change in cognitive function by adherence to healthy diets.

RESULTS

The highest tertiles of the mMDS, HDI, and mDHD15-index were associated with better cognitive function compared with the lowest tertiles (P values <0.01), for instance at age 65 y equal to being 2 y cognitively younger in global cognition. In addition, compared with the lowest tertiles, the highest tertiles of the mMDS, HDI, and mDHD15-index were statistically significantly associated with 6-7% slower global cognitive decline from age 55 to 75 y, but also slower decline in processing speed (for mMDS: 10%; 95% CI: 2, 18%; for mDHD15: 12%; 95% CI: 6, 21%) and cognitive flexibility (for mDHD15: 10%; 95% CI: 4, 18%).

CONCLUSIONS

Healthier dietary habits, determined by higher adherence to dietary guidelines, are associated with better cognitive function and slower cognitive decline with aging from middle age onwards.

Association Between Cognitive Impairment and Vitamin B12, Folate, and Homocysteine Status in Elderly Adults: A Retrospective Study

BACKGROUND

Cognitive disorders in old age have a serious impact on the health and social aspects of patients and their families.

OBJECTIVE

The scope of this paper is to explore the role of cobalamin and folate that has been linked to cognitive decline, not only as a deficiency state depending on malnutrition, but also a determinant in cognitive impairment.

METHODS

A 6-year observational, retrospective study was conducted by collecting the routine blood analyses and cognitive screening scores of patients aged 60 years or older, followed at our Centre for the Diagnosis and Treatment of Cognitive Disorders.

RESULTS

In a linear regression with a multi-vitamin model, higher folate concentrations were correlated with better cognitive performances through MMSE score, even after correction for sex, age, and years of education (beta = 0.144, p = 0.001). Estimated MMSE marginal means for folate versus homocysteine showed that folate deficiency was associated with worse cognitive performances, with a more severe cognitive impairment when hyperhomocysteinemia was present.

CONCLUSION

The assessment of B-vitamin status among elderly adults can contribute to an economic and practical approach to the prevention and management of cognitive decline. Future studies focused to define optimal vitamin status are warranted.

Maternal choline supplementation ameliorates Alzheimer's disease pathology by reducing brain homocysteine levels across multiple generations

The lack of effective treatments for Alzheimer's disease (AD) is alarming, considering the number of people currently affected by this disorder and the projected increase over the next few decades. Elevated homocysteine (Hcy) levels double the risk of developing AD. Choline, a primary dietary source of methyl groups, converts Hcy to methionine and reduces age-dependent cognitive decline. Here, we tested the transgenerational benefits of maternal choline supplementation (ChS; 5.0 g/kg choline chloride) in two generations (Gen) of APP/PS1 mice. We first exposed 2.5-month-old mice to the ChS diet and allowed them to breed with each other to generate Gen-1 mice. Gen-1 mice were exposed to the ChS diet only during gestation and lactation; once weaned at postnatal day 21, Gen-1 mice were then kept on the control diet for the remainder of their life. We also bred a subset of Gen-1 mice to each other and obtained Gen-2 mice; these mice were never exposed to ChS. We found that ChS reduced Aβ load and microglia activation, and improved cognitive deficits in old Gen-1 and Gen-2 APP/PS1 mice. Mechanistically, these changes were linked to a reduction in brain Hcy levels in both generations. Further, RNA-Seq data from APP/PS1 hippocampal tissue revealed that ChS significantly changed the expression of 27 genes. These genes were enriched for inflammation, histone modifications, and neuronal death functional classes. Our results are the first to demonstrate a transgenerational benefit of ChS and suggest that modifying the maternal diet with additional choline reduces AD pathology across multiple generations.

Dietary Micronutrients Intake Status among Chinese Elderly People Living at Home: Data from CNNHS 2010-2012

The aim of this study was to examine the status of usual dietary micronutrient intakes among Chinese elderly living at home. The data was based on China National Nutrition and Health Survey (CNNHS) 2010-2012. We analyzed data from the participants aged 60-year-old and more (n = 16,612) living at home, who provided dietary data on three days 24 h dietary survey combining with the household weighing method. The means and distribution percentiles for usual intakes of dietary micronutrients were estimated using the Multiple Source Method (MSM). The prevalence of inadequacy for the selected micronutrients was expressed using the proportion of individuals with usual intakes below the Estimated Average Requirement (EAR). For vitamin E, sodium and potassium, the means and the distribution of intakes were compared to the Adequate Intake (AI) level. Usual dietary intakes of most micronutrients were inadequate in the participants, especially folate, calcium, vitamin B6 and vitamin B2, with the prevalence of inadequacy more than 90%. However, dietary sodium intake was extremely high with an average usual intake of 4702 mg/day. The usual dietary intakes of all selected micronutrients in old males were higher than females, and the prevalence of inadequacy of most micronutrients was higher in old women (p < 0.01). The subjects aged 60-74 years tended to have higher usual dietary micronutrient intakes and lower prevalence of inadequate micronutrients than those aged 75 years and over (p < 0.01). Higher usual dietary intakes and lower prevalence of inadequacy of most micronutrients were found in the elderly living in the southern region (p < 0.01). The average usual intakes of most micronutrients declined with socioeconomic status. The prevalence of inadequate vitamin A, B2, C, calcium and selenium below EAR increased with socioeconomic status (p < 0.01, p for trend < 0.01). Thus, essential micronutrients insufficient intake is a public health concern among Chinese community-dwelling old population, especially the females, older people, the elderly in undeveloped areas or living in northern regions. Nutrition education and appropriate approach should be undertaken to address these problems.

Lycopene and cognitive function

Decreases in cognitive function related to increases in oxidative stress and inflammation occur with ageing. Acknowledging the free radical-quenching activity and anti-inflammatory action of the carotenoid lycopene, the aim of the present review was to assess if there is evidence for a protective relationship between lycopene and maintained cognitive function or between lycopene and development or progression of dementia. A systematic literature search identified five cross-sectional and five longitudinal studies examining these outcomes in relation to circulating or dietary lycopene. Among four studies evaluating relationships between lycopene and maintained cognition, three reported significant positive relationships. Neither of the two studies reporting on relationship between lycopene and development of dementia reported significant results. Of four studies investigating circulating lycopene and pre-existing dementia, only one reported significant associations between lower circulating lycopene and higher rates of Alzheimer's disease mortality. Acknowledging heterogeneity among studies, there is insufficient evidence and a paucity of data to draw firm conclusions or tease apart direct effects of lycopene. Nevertheless, as low circulating lycopene is a predictor of all-cause mortality, further investigation into its relationship with cognitive longevity and dementia-related mortality is warranted.

Hyperhomocysteinemia and risk of incident cognitive outcomes: An updated dose-response meta-analysis of prospective cohort studies

OBJECTIVE

This study aimed to comprehensively assess the dose-response relationship between blood homocysteine levels and risk of all cause, Alzheimer and vascular dementia, as well as cognitive impairment without dementia (CIND).

METHOD

We searched for all related prospective cohort studies reporting homocysteine as an exposure from patients with cognitive disorders as a result in the PubMed and EMBASE databases up to June 18, 2018. Pooled relative risks (RRs) and corresponding 95% confidence intervals (CIs) were extracted. The dose-response meta-analyses were conducted to assess potential linear and non-linear dose-response relations. Summary RRs and 95% CIs were calculated using a random- or fixed-effects model.

RESULTS

Twenty-eight prospective cohort studies were eligible in this meta-analysis. During average follow-up periods ranging from 2.7 to 35 years there were 2557 cases (1035 all-cause dementia, 530 Alzheimer's disease, 92 vascular dementia and > 900 CIND) among 28,257 participants. There was a clear linear dose-response relationship between blood homocysteine concentration and risk of Alzheimer-type dementia (P > 0.05 for non-linearity). The pooled RR of Alzheimer-type dementia was 1.15 (95% CI: 1.04 to 1.26; I² = 56.6%, n = 5) for every 5 μmol/L increase in blood homocysteine. Sensitivity analysis showed similar results, and there was no clear evidence of publication bias with Begg's and Egger's tests for Alzheimer dementia (P = 0.806, 0.084, respectively), strengthening the linear relationship between blood homocysteine levels and risk of Alzheimer dementia. Due to the presence of publication bias and low statistical power, elevated levels of blood homocysteine were not appreciably associated with risk of all-cause, vascular dementia and CIND.

CONCLUSIONS

Every 5 μmol/L increase in blood homocysteine is linearly associated with a 15% increase in relative risk of Alzheimer-type dementia. This meta-analysis provides further evidence that a higher concentration of blood homocysteine is associated with a higher risk of Alzheimer-type dementia.

Homocysteine and Dementia: An International Consensus Statement

Identification of modifiable risk factors provides a crucial approach to the prevention of dementia. Nutritional or nutrient-dependent risk factors are especially important because dietary modifications or use of dietary supplements may lower the risk factor level. One such risk factor is a raised concentration of the biomarker plasma total homocysteine, which reflects the functional status of three B vitamins (folate, vitamins B12, B6). A group of experts reviewed literature evidence from the last 20 years. We here present a Consensus Statement, based on the Bradford Hill criteria, and conclude that elevated plasma total homocysteine is a modifiable risk factor for development of cognitive decline, dementia, and Alzheimer’s disease in older persons. In a variety of clinical studies, the relative risk of dementia in elderly people for moderately raised homocysteine (within the normal range) ranges from 1.15 to 2.5, and the Population Attributable risk ranges from 4.3 to 31%. Intervention trials in elderly with cognitive impairment show that homocysteine-lowering treatment with B vitamins markedly slows the rate of whole and regional brain atrophy and also slows cognitive decline. The findings are consistent with moderately raised plasma total homocysteine (>11 μmol/L), which is common in the elderly, being one of the causes of age-related cognitive decline and dementia. Thus, the public health significance of raised tHcy in the elderly should not be underestimated, since it is easy, inexpensive, and safe to treat with B vitamins. Further trials are needed to see whether B vitamin treatment will slow, or prevent, conversion to dementia in people at risk of cognitive decline or dementia.

Pharmacoepigenomic Interventions as Novel Potential Treatments for Alzheimer's and Parkinson's Diseases

Cerebrovascular and neurodegenerative disorders affect one billion people around the world and result from a combination of genomic, epigenomic, metabolic, and environmental factors. Diagnosis at late stages of disease progression, limited knowledge of gene biomarkers and molecular mechanisms of the pathology, and conventional compounds based on symptomatic rather than mechanistic features, determine the lack of success of current treatments, including current FDA-approved conventional drugs. The epigenetic approach opens new avenues for the detection of early presymptomatic pathological events that would allow the implementation of novel strategies in order to stop or delay the pathological process. The reversibility and potential restoring of epigenetic aberrations along with their potential use as targets for pharmacological and dietary interventions sited the use of epidrugs as potential novel candidates for successful treatments of multifactorial disorders involving neurodegeneration. This manuscript includes a description of the most relevant epigenetic mechanisms involved in the most prevalent neurodegenerative disorders worldwide, as well as the main potential epigenetic-based compounds under investigation for treatment of those disorders and their limitations.

Glycerophospholipid Supplementation as a Potential Intervention for Supporting Cerebral Structure in Older Adults

Modifying nutritional intake through supplementation may be efficacious for altering the trajectory of cerebral structural decline evident with increasing age. To date, there have been a number of clinical trials in older adults whereby chronic supplementation with B vitamins, omega-3 fatty acids, or resveratrol, has been observed to either slow the rate of decline or repair cerebral tissue. There is also some evidence from animal studies indicating that supplementation with glycerophospholipids (GPL) may benefit cerebral structure, though these effects have not yet been investigated in adult humans. Despite this paucity of research, there are a number of factors predicting poorer cerebral structure in older humans, which GPL supplementation appears to beneficially modify or protect against. These include elevated concentrations of homocysteine, unbalanced activity of reactive oxygen species both increasing the risk of oxidative stress, increased concentrations of pro-inflammatory messengers, as well as poorer cardio- and cerebrovascular function. As such, it is hypothesized that GPL supplementation will support cerebral structure in older adults. These cerebral effects may influence cognitive function. The current review aims to provide a theoretical basis for future clinical trials investigating the effects of GPL supplementation on cerebral structural integrity in older adults.

The effect of N-acetylcysteine (NAC) on human cognition - A systematic review

Oxidative stress, neuroinflammation and neurogenesis are commonly implicated as cognitive modulators across a range of disorders. N-acetylcysteine (NAC) is a glutathione precursor with potent antioxidant, pro-neurogenesis and anti-inflammatory properties and a favourable safety profile. A systematic review of the literature specifically examining the effect of NAC administration on human cognition revealed twelve suitable articles for inclusion: four examining Alzheimer's disease; three examining healthy participants; two examining physical trauma; one examining bipolar disorder, one examining schizophrenia, and one examining ketamine-induced psychosis. Heterogeneity of studies, insufficiently powered studies, infrequency of cognition as a primary outcome, heterogeneous methodologies, formulations, co-administered treatments, administration regimes, and assessment confounded the drawing of firm conclusions. The available data suggested statistically significant cognitive improvements following NAC treatment, though the paucity of NAC-specific research makes it difficult to determine if this effect is meaningful. While NAC may have a positive cognitive effect in a variety of contexts; larger, targeted studies are warranted, specifically evaluating its role in other clinical disorders with cognitive sequelae resulting from oxidative stress and neuroinflammation.

Collaborative Management of Neurocognitive Disorders in Primary Care: Explorations of an Attempt at Culture Change

INTRODUCTION

Minor neurocognitive disorder (MiND; previously mild cognitive impairment) is a transitional zone between normal cognitive function and early stages of major neurocognitive disorder (previously called dementia). Of people with MiND, 5% to 10% progress to major neurocognitive disorder. Simple interventions such as memory activities, balance exercises, and anti-inflammatory diets have been shown to improve cognitive ability. Also, education and support in group settings have proved beneficial for patients with MiND.

DESIGN

Survey evaluation of outcomes of geriatric consultation and prospective educational study.

MAIN OUTCOME MEASURES

We collaborated with an academic training program to introduce into primary care the ideas of educational activities and participation in group medical care for people with MiND. Educational programs were developed and presented to family medicine residents and practicing physicians, and their knowledge was assessed before and after education.

RESULTS

Two group programs were implemented: one at our hospital and one at a local skilled nursing facility. These were initially envisioned as time-limited, but participants insisted on their continuance. Thirty-two different patients attended the groups for at least six sessions. Participants enthusiastically reported positive change on qualitative interviews and showed improvement in cognition, balance, and self-esteem. Family medicine residents and practicing physicians both shifted toward lifestyle medicine and significantly changed their views on the efficacy of treatments. Despite these activities, community physicians making referrals for geriatric consultations did not change their discussions with patients and families about exercise, diet, cognitive enhancement, and socialization for MiND.

CONCLUSION

Group visits that emphasized support for increased exercise, improved diet, more movement and balance, and cognitive enhancement appear to please and benefit patients with MiND. Physicians are more open to these approaches with training after initial skepticism. A struggle exists to convince the profession that lifestyle change may be beneficial in MiND.

Homocysteine and cognition: A systematic review of 111 studies

BACKGROUND

Elevated plasma homocysteine ​​(Hcy) levels have been associated with cognitive dysfunction in a wide range of conditions. The aim of this review is to establish which cognitive domains and populations are the most affected.

METHODS

We systematically review the literature and consider all articles that showed any relationship between plasma Hcy levels and scores achieved on cognitive performance tests in both, the general population and patients suffering from central nervous system disorders and other diseases. When effect sizes were available and combinable, several meta-analyses were performed.

RESULTS

We found 111 pertinent articles. There were 24 cohort studies, 18 randomized trials, 21 case-control studies, and 48 cross-sectional studies. This review reveals a positive trend between cognitive decline and increased plasma Hcy concentrations in general population and in patients with cognitive impairments. Results from the meta-analyses also confirm this trend. Treatment with vitamin supplementation fails to show a reduction in cognitive decline.

DISCUSSION

Further investigations are warranted to clarify this relationship. Earlier detection of the elevated Hcy levels may be an effective intervention to prevent cognitive impairment and dementia.

Hyperhomocysteinemia and risk of cognitive decline: a meta-analysis of prospective cohort studies

OBJECTIVE

To evaluate the association between hyperhomocysteinemia (HHcy) and risk of cognitive decline.

METHODS

Electronic databases such as PubMed and EMBASE were searched for prospective cohort studies that involved the relationship between HHcy and risk of cognitive decline. Adjusted risk ratios (RRs) and corresponding 95% confidence intervals (95% CIs) were calculated by Review Manager 5.2.7. Subgroup analyses were conducted on stratification of some important variables.

RESULTS

Fourteen publications were included in the analysis. The pooled RR was 1.53 (95% CI, 1.23-1.91; p = 0.0002) for patients with HHcy compared to subjects without HHcy. Subgroup analyses indicated that the pooled RRs were 1.51 (95% CI, 1.10-2.05; p = 0.01) for more than five-year follow-up studies and 1. 56 (95% CI, 1.13-2.14; p = 0.007) for less than five-year follow-up studies. The pooled RRs were 1.66 (95% CI, 1.21-2.26; p = 0.001) for studies excluding the confounder of B vitamins and 1.34 (95% CI, 1.08-1.66; p = 0.008) for non-excluded studies. In terms of region, the pooled RR was 1.60 (95% CI, 1.21-2.13; p = 0.001) for European and American countries, while the pooled RR was 1.27 (95% CI, 1.02-1.59; p = 0.03) for other regions.

CONCLUSION

As one of the independent risk factors, HHcy was associated with an increased risk of cognitive decline.