Serum folate concentration, cognitive impairment, and DNA damage among elderly individuals in Malaysia

MTHFR Gene and Serum Folate Interaction on Serum Homocysteine Lowering: Prospect for Precision Folic Acid Treatment

OBJECTIVE

This post hoc analysis of the CSPPT (China Stroke Primary Prevention Trial) assessed the individual variation in total homocysteine (tHcy)-lowering response after an average 4.5 years of 0.8 mg daily folic acid therapy in Chinese hypertensive adults and evaluated effect modification by methylenetetrahydrofolate reductase (MTHFR) C677T genotypes and serum folate levels.

APPROACH AND RESULTS

This analysis included 16 413 participants from the CSPPT, who were randomly assigned to 2 double-blind treatment groups: either 10-mg enalapril+0.8-mg folic acid or 10-mg enalapril, daily and had individual measurements of serum folate and tHcy levels at baseline and exit visits and MTHFR C677T genotypes. Mean baseline tHcy levels were comparable between the 2 treatment groups (14.5±8.5 versus 14.4±8.1 μmol/L; P=0.561). After 4.5 years of treatment, mean tHcy levels were reduced to 12.7±6.1 μmol/L in the enalapril+folic acid group, but almost stayed the same in the enalapril group (14.4±7.9 μmol/L, group difference: 1.61 μmol/L; 11% reduction). More importantly, tHcy lowering varied by MTHFR genotypes and serum folate levels. Compared with CC and CT genotypes, participants with the TT genotype had a more prominent L-shaped curve between tHcy and serum folate levels and required higher folate levels (at least 15 ng/mL) to eliminate the differences in tHcy by genotypes.

CONCLUSIONS

Compared with CC or CT, tHcy in the TT group manifested a heightened L-shaped curve from low to high folate levels, but this difference in tHcy by genotype was eliminated when plasma folate levels reach ≈15 ng/mL or higher. Our data raised the prospect to tailor folic acid therapy according to individual MTHFR C677T genotype and folate status.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00794885.

DNA Damage, Copper and Lead Associates with Cognitive Function among Older Adults

BACKGROUND

A cross sectional study was conducted in a group of 317 subjects older than 60 in Malaysia, aimed to determine risk factors associated with cognitive impairment in older adults, focusing on trace elements and DNA damage.

METHOD

Cognitive decline was determined by Montreal Cognitive Assessment (MoCA). Oxidative stress markers (malondialdehyde-MDA and superoxide dismutase-SOD) were determined and DNA damage was assayed using Alkaline Comet Assay. Toenail samples were taken and analyzed using ICP-MS to determine trace element levels.

RESULTS

A total of 62.1 % of subjects had cognitive impairment. Subjects with cognitive impairment had significantly higher levels of MDA and DNA damage as compared to the group with normal cognitive function; MDA (2.07 ± 0.05 nmol/L vs 1.85 ± 0.06 nmol/L) (p<0.05) and DNA damage (% Tail Density, 14.52 ± 0.32 vs 10.31 ± 0.42; Tail Moment, 1.79 ± 0.06 vs 1.28 ± 0.06) (p<0.05 for all parameters). However, the level of SOD among subjects with cognitive impairment (6.67 ± 0.33 u.e/min/mg protein) was lower than the level among those with normal cognitive functions (11.36 ± 0.65 u.e/min/mg protein) (p<0.05). Multiple logistic regression revealed the predictors for cognitive impairment among the subjects were DNA damage (Adjusted odd ratio [OR], 1.37; 95% confidence interval [CI], 1.18-1.59), level of trace elements in toenails namely, lead (OR, 2.471; CI, 1.535-3.980) and copper (OR, 1.275; CI, 1.047-1.552) (p<0.05).

CONCLUSION

High levels of lead and copper can lead to increase in oxidative stress levels and are associated with DNA damage that eventually could be associated with cognitive decline.

Cognitive impairment, genomic instability and trace elements

Cognitive impairments are often related to aging and micronutrient deficiencies. Various essential micronutrients in the diet are involved in age-altered biological functions such as, zinc, copper, iron, and selenium that play pivotal roles either in maintaining and reinforcing the antioxidant performances or in affecting the complex network of genes (nutrigenomic approach) involved in encoding proteins for biological functions. Genomic stability is one of the leading causes of cognitive decline and deficiencies or excess in trace elements are two of the factors relating to it. In this review, we report and discuss the role of micronutrients in cognitive impairment in relation to genomic stability in an aging population. Telomere integrity will also be discussed in relation to aging and cognitive impairment, as well as, the micronutrients related to these events. This review will provide an understanding on how these three aspects can relate with each other and why it is important to keep a homeostasis of micronutrients in relation to healthy aging. Micronutrient deficiencies and aging process can lead to genomic instability.

Is the oxidative DNA damage level of human lymphocyte correlated with the antioxidant capacity of serum or the base excision repair activity of lymphocyte?

A random screening of human blood samples from 24 individuals of nonsmoker was conducted to examine the correlation between the oxidative DNA damage level of lymphocytes and the antioxidant capacity of serum or the base excision repair (BER) activity of lymphocytes. The oxidative DNA damage level was measured with comet assay containing Fpg/Endo III cleavage, and the BER activity was estimated with a modified comet assay including nuclear extract of lymphocytes for enzymatic cleavage. Antioxidant capacity was determined with trolox equivalent antioxidant capacity assay. We found that though the endogenous DNA oxidation levels varied among the individuals, each individual level appeared to be steady for at least 1 month. Our results indicate that the oxidative DNA damage level is insignificantly or weakly correlated with antioxidant capacity or BER activity, respectively. However, lymphocytes from carriers of Helicobacter pylori (HP) or Hepatitis B virus (HBV) tend to give higher levels of oxidative DNA damage (P < 0.05). Though sera of this group of individuals show no particular tendency with reduced antioxidant capacity, the respective BER activities of lymphocytes are lower in average (P < 0.05). Thus, reduction of repair activity may be associated with the genotoxic effect of HP or HBV infection.

Leukocyte DNA Damage and Wound Infection after Nitrous Oxide Administration

Background:

Nitrous oxide inactivates methionine synthase and may lead to DNA damage and wound infection. By using single-cell gel electrophoresis (comet assay), the authors determined the effect of nitrous oxide on DNA damage in circulating leukocytes.

Methods:

In this double-blind, randomized controlled trial, 91 patients undergoing major colorectal surgery were randomized to receive 70% nitrous oxide (n = 31) or nitrous oxide-free anesthesia using 30 (n = 30) or 80% (n = 30) oxygen. Venous blood was collected before and 24 h after surgery. The primary outcome was extent of DNA damage, quantified as the percentage of DNA staining intensity in the comet tail using digital fluorescence microscopy. Incidence of postoperative wound infection was also recorded.

Results:

Nitrous oxide exposure was associated with a two-fold increase in the percentage of DNA intensity in tail (P = 0.0003), but not in the 30 (P = 0.181) or 80% oxygen groups (P = 0.419). There was a positive correlation between the duration of nitrous oxide exposure and extent of DNA damage, r = 0.33, P = 0.029. However, no correlation was observed in nitrous oxide-free patients. The proportions of postoperative wound infection, using the Centers for Disease Control and Prevention criteria, were 19.4% (6 of 31) in the 70% nitrous oxide group and 6.7% (2 of 30) in both the 30 and 80% oxygen groups, P = 0.21. An increase in DNA damage was associated with a higher risk of wound infection, adjusted odds ratio (95% CIs): 1.19 (1.07–1.34), P = 0.003.

Conclusions:

Nitrous oxide increased DNA damage compared with nitrous oxide-free anesthesia and was associated with postoperative wound infection.

Association between vitamin A, vitamin E and apolipoprotein E status with mild cognitive impairment among elderly people in low-cost residential areas

RATIONALE

The influence of nutritional parameters and genetic susceptibility on poor cognitive impairment has been documented; however, the association between lipid-soluble vitamins with genetic susceptibility on mild cognitive impairment (MCI) has not yet been studied extensively.

OBJECTIVES

The aim of the present study was (i) to determine the prevalence of MCI and its associated risk factors and (2) to investigate the influence of the apolipoprotein E (APOE) ε4 allele on peripheral vitamin A and E concentration in MCI and non-MCI groups.

METHODS

A total of 333 subjects aged 60 years and above, residing in public housing areas in Kuala Lumpur, Malaysia were interviewed to obtain information on their neuropsychological status. Fasting venous blood was taken for determination of vitamin A and vitamin E concentration using high-performance liquid chromatography. Restriction fragment length polymorphism analysis was performed to determine the APOE genotypes.

RESULTS

The prevalence of MCI was 21.1%. Binary logistic regression indicated that the predictors of MCI were being married, overweight or obesity, and had vitamin A deficiency. In non-MCI subjects, vitamin E levels were lower among APOEε4 allele carriers as compared to the non-carriers (P < 0.05).

CONCLUSION

The study highlighted the importance of maintaining good nutritional status and vitamin A status for optimal cognitive function. The presence of APOEε4 allele has a prominent role in affecting vitamin E levels, particularly among cognitively healthy elderly in our unique population.

Low and high homocysteine are associated with mortality independent of B group vitamins but interactive with cognitive status in a free-living elderly cohort

Hyperhomocysteinemia and cognitive impairment both predict mortality and partly because of dietary associations. We have hypothesized that for, nutritional reasons, homocysteine and cognition may act jointly to determine elder survival. In a Nutrition and Health Survey in Taiwan (1999-2000), some 1412 representative elderly were followed up for mortality up to 10 years. Cognition was assessed by the Short Portable Mental Status Questionnaire. Food and B vitamin intakes with their biomarkers, and plasma homocysteine, were measured at baseline. The possible effects of cognition on homocysteine-associated mortality were ascertained with Cox proportional-hazards models. Homocysteine was higher in those who were older, male, and single, consumed less fish and tea, and with alcohol and smoking. In models adjusted for these variables, when homocysteine exceeded 14.5 μmol/L, mortality was 1.80-fold more than when <9.3 μmol/L (hazard ratio [HR], 1.80; 95% confidence interval [95% CI], 1.20-2.71). P for trend was 0.002 and interactive with sex (P < .002). However, these homocysteine-mortality associations were dependent on cognition (P = .03); adjustment for food intake or nutrient status made little difference. Homocysteine did not predict cognitive impairment (adjusted OR, 1.40; 95% CI = 0.50-3.93). Vitamins B(1), B(2), and B(6) accounted somewhat for cognitive impairment. Cognition predicted mortality, fully adjusted for available covariates and also for homocysteine (HR, 3.66; 95% CI, 1.64-8.20) but interactively with homocysteine. Thus, the B-group vitamin insufficiency and cognitive impairment associations with premature mortality are confirmed. Yet cognition is inter-related with homocysteine in its association with survival in ways not detectably altered by foods or food-derived vitamins.

Dietary quality may enhance survival related to cognitive impairment in Taiwanese elderly

Background

Impaired cognition increases mortality in the aged. It is unclear how dietary quality might affect this relationship.

Objective

To examine how dietary diversity and cognition might interact to determine survival.

Design

In a Nutrition and Health Survey in Taiwan (NAHSIT 1999–2000), 1,839 representative elderly were followed for mortality up to 10 years. The dietary quality measure was a dietary diversity score (DDS, range: 0–6) to present six food groups (dairy, meat, rice and grains, fruit, vegetable,fat and oil) derived from a 24-h dietary recall. Cognitive function was evaluated by the validated Short Portable Mental Status Questionnaire (SPMSQ).

Results

Those with cognitive impairment (SPMSQ≥3 errors) had 2.56 (95% confidence intervals (CI), 1.99–3.28) times the all-cause-mortality risk of those with intact cognition. After control for potential confounders, the adjusted hazard ratio (HR) remained significant (1.46, 95% CI: 1.06–2.02). Significant interactions for DDS and cognition were found (p<0.001). Jointly, compared to normal-SPMSQ-highest DDS, the greatest HR is where impaired cognition is combined with the lowest DDS (HR 2.24, 95% CI: 1.19–4.24). Increased DDS was associated with improvement in survival that is especially evident in those with 1–2 errors where the greatest HR reduction was found, and for fruit. Attributability for mortality amounted to 18% for impaired cognition and 33% for least diverse diet.

Conclusions

Dietary diversity may improve survival in relation to impaired cognitive function.

Prevalence of gender disparities and predictors affecting the occurrence of mild cognitive impairment (MCI)

The aims were to investigate the prevalence of mild cognitive impairment (MCI) within gender disparities in Malaysian older adults, and to determine the predictors of MCI according to gender disparities. A community-based sample of urban, multiethnic dwelling elderly aged 60 years of age and above from Cheras, Kuala Lumpur was recruited. Prevalence of all-type MCI, amnestic-type MCI (am-MCI) and non-amnestic-type MCI (nam-MCI) was assessed using comprehensive neuropsychological batteries. The association between demography, socioeconomic status, lifestyle practices, and nutritional status and health risk factors with MCI were examined. Predictors of MCI occurrence between gender disparities were determined. The prevalence of all-type MCI, am-MCI and nam-MCI was 21.1%, 15.4% and 5.7%, respectively. Binary logistic regression indicated that hypercholesterolemia is the significant predictor for MCI in men after adjustment for age, ethnicity and total years of education. While, in women, MCI was best predicted by married status, without exercise practice, overweight and obesity. These results suggest that approximately one-fifth of the studied elderly people had MCI. Predictors for MCI are totally different between men and women. It is critical to identify those at higher risk for MCI in order to implement preventative measures to delay or reverse this abnormal condition.