Relationship between oxidative stress and cognitive impairment in the elderly of rural vs. urban communities

Air pollution and human cognition: A systematic review and meta-analysis

BACKGROUND

This systematic review summarises and evaluates the literature investigating associations between exposure to air pollution and general population cognition, which has important implications for health, social and economic inequalities, and human productivity.

METHODS

The engines MEDLINE, Embase Classic+Embase, APA PsycInfo, and SCOPUS were searched up to May 2022. Our inclusion criteria focus on the following pollutants: particulate matter, NOx, and ozone. The cognitive abilities of interest are: general/global cognition, executive function, attention, working memory, learning, memory, intelligence and IQ, reasoning, reaction times, and processing speed. The collective evidence was assessed using the NTP-OHAT framework and random-effects meta-analyses.

RESULTS

Eighty-six studies were identified, the results of which were generally supportive of associations between exposures and worsened cognition, but the literature was varied and sometimes contradictory. There was moderate certainty support for detrimental associations between PM_2.5 and general cognition in adults 40+, and PM_2.5, NOx, and PM₁₀ and executive function (especially working memory) in children. There was moderate certainty evidence against associations between ozone and general cognition in adults age 40+, and NOx and reasoning/IQ in children. Some associations were also supported by meta-analysis (N = 14 studies, all in adults aged 40+). A 1 μg/m³ increase in NO₂ was associated with reduced performance on general cognitive batteries (β = -0.02, p < 0.05) as was a 1 μg/m³ increase in PM_2.5 exposure (β = -0.02, p < 0.05). A 1μgm³ increase in PM_2.5 was significantly associated with lower verbal fluency by -0.05 words (p = 0.01) and a decrease in executive function task performance of -0.02 points (p < 0.001).

DISCUSSION

Evidence was found in support of some exposure-outcome associations, however more good quality research is required, particularly with older teenagers and young adults (14-40 years), using multi-exposure modelling, incorporating mechanistic investigation, and in South America, Africa, South Asia and Australasia.

Association of inflammation and cognition in the elderly: A systematic review and meta-analysis

Background

The development of mild cognitive impairment (MCI) and Alzheimer's disease (AD) may be associated with an inflammatory process. Inflammatory cytokines may be a surrogate for systemic inflammation leading to worsening neurological function. We aim to investigate the association between cognitive impairment and inflammation by pooling and analyzing the data from previously published studies.

Methods

We performed a systematic literature search on MEDLINE, PubMed, Embase, Web of Science, and Scopus for prospective longitudinal and cross-sectional studies evaluating the relationship between inflammation and cognitive functions.

Results

A total of 79 articles were included in our systematic review and meta-analysis. Pooled estimates from cross-sectional studies have demonstrated an increased level of C-reactive protein (CRP) [Hedges's g 0.35, 95% CI (0.16, 0.55), p < 0.05], IL-1β [0.94, 95% CI (-0.04, 1.92), p < 0.05], interleukin-6 (IL-6) [0.46, 95% CI (0.05, 0.88), p < 0.005], TNF alpha [0.22, 95% CI (-0.24, 0.68), p < 0.05], sTNFR-1 [0.74, 95% CI (0.46, 1.02), p < 0.05] in AD compared to controls. Similarly, higher levels of IL-1β [0.17, 95% CI (0.05, 0.28), p < 0.05], IL-6 [0.13, 95% CI (0.08, 0.18), p < 0.005], TNF alpha [0.28, 95% CI (0.07, 0.49), p < 0.05], sTNFR-1 [0.21, 95% CI (0.05, 0.48), p < 0.05] was also observed in MCI vs. control samples. The data from longitudinal studies suggested that levels of IL-6 significantly increased the risk of cognitive decline [OR = 1.34, 95% CI (1.13, 1.56)]. However, intermediate levels of IL-6 had no significant effect on the final clinical endpoint [OR = 1.06, 95% CI (0.8, 1.32)].

Conclusion

The data from cross-sectional studies suggest a higher level of inflammatory cytokines in AD and MCI as compared to controls. Moreover, data from longitudinal studies suggest that the risk of cognitive deterioration may increase by high IL-6 levels. According to our analysis, CRP, antichymotrypsin (ACT), Albumin, and tumor necrosis factor (TNF) alpha may not be good surrogates for neurological degeneration over time.

Inflammatory, oxidative stress and cognitive functions in patients under maintenance treatment with methadone or buprenorphine and healthy subjects

BACKGROUND

Methadone and buprenorphine which are widely used for opioid maintenance treatment can affect redox status and also brain functions. The present study aimed to compare inflammation, oxidative stress, and cognitive function in methadone maintenance patients (MMP), buprenorphine maintenance patients (BMP), and healthy participants.

METHOD

Oxidative- antioxidant markers, inflammatory factors were investigated in MMP (n = 30), BMP (n = 30), and healthy participants (n = 30) by evaluating the ferritin, malondialdehyde (MDA), total antioxidant capacity (TAC), and also High-sensitivity C-reactive protein (hs-CRP). Also, executive function was evaluated using Wisconsin Card Sorting Test (WCST).

FINDINGS

MMP and BMP showed impairment in executive function compared to the healthy participants. Both buprenorphine and methadone treatments induced oxidative stress. The ferritin level in BMP was significantly lower compared to MMP and healthy participants (P = 0.01). There was a significant difference between control and MMP and BMP (P > 0.0001) in terms of hs-CRP level. BMP had the highest and healthy participant's lowest MDA level (P < 0.001). The TAC levels in BMP were lower than in MMP (p = 0.002) and healthy participants (p = 0.001). Finally, executive function was significantly correlated with oxidative-antioxidant status.

DISCUSSION

Both methadone and buprenorphine induced severe oxidative activity (especially buprenorphine) and cognitive deficits compared to healthy participants. Stress oxidative can affect normal brain activity and consequently cognitive functions. It's suggested that concomitant antioxidant administration with buprenorphine or methadone can potentially enhance their beneficial action by regulating blood redox status.

Survey of risk factors and frequency of clinical signs observed with feline cognitive dysfunction syndrome

OBJECTIVES

The aims of this study were to distribute a survey to cat owners to identify common clinical signs of feline cognitive dysfunction (FCD) and to evaluate for potential risk factors.

METHODS

A questionnaire was developed and adapted based on previously validated canine cognitive dysfunction questionnaires. This questionnaire was distributed to 4342 cat owners who had presented to Colorado State University Veterinary Teaching Hospital between 2015 and 2020. Cats aged ⩾8 years with signs of cognitive dysfunction and no underlying medical conditions were classified as the FCD-positive group. Cats aged ⩾8 years with no signs of cognitive dysfunction were classified as the FCD-negative control group. Chi-square or Fisher's exact tests were used to determine associations between categorical variables and a P value <0.05 was considered indicative of evidence of association.

RESULTS

A total of 615 completed survey responses were recorded, which was a response rate of 14.2%. Among those, 80 (13%) cats were identified as the FCD-positive group and 114 (18.5%) were identified as the FCD-negative control group. The most common clinical sign in the FCD-positive group was inappropriate vocalization (32/80, 40.0%). The only variable determined to have an association with the FCD group (positive or negative), with a P value of 0.033, was the environmental setting. Cats living in a rural environment (FCD-positive or -negative) had the largest contribution to the χ2 statistic.

CONCLUSION AND RELEVANCE

The observed number of FCD-positive cats living in a rural community was less than the expected value based on the χ2 tests. This is suggestive of an association between living in a rural environment and a reduced chance of cognitive dysfunction. There are many factors such as air pollution, social interactions and environmental enrichment that need to be studied further to determine how they relate to FCD as this could not be concluded from this study.

Utilizing the "One Health" Model to Study Human Aging in Urban Environments

The "One Health" concept has resulted in a rich research literature that integrates human and animal systems, with a focus on zoonotic diseases; however, this narrow focus is at the expense of one of the leading causes of global human mortality: non-infectious, chronic diseases. Here, we provide a viewpoint that applying the integrated One Health framework to public health issues such as the impact of stressful urban environments on the process of human aging has the potential to elucidate potential causal mechanisms that have previously gone unnoticed. Given the success of the One Health paradigm in studying human health in rural areas, we posit that this model would be a useful tool for studying human, animal, and environmental interactions in urban settings.

The Air We Breathe: Air Pollution as a Prevalent Proinflammatory Stimulus Contributing to Neurodegeneration

Air pollution is regarded as an important risk factor for many diseases that affect a large proportion of the human population. To date, accumulating reports have noted that particulate matter (PM) is closely associated with the course of cardiopulmonary disorders. As the incidence of Alzheimer’s disease (AD), Parkinson’s disease (PD), and autoimmune disorders have risen and as the world’s population is aging, there is an increasing interest in environmental health hazards, mainly air pollution, which has been slightly overlooked as one of many plausible detrimental stimuli contributing to neurodegenerative disease onset and progression. Epidemiological studies have indicated a noticeable association between exposure to PM and neurotoxicity, which has been gradually confirmed by in vivo and in vitro studies. After entering the body directly through the olfactory epithelium or indirectly by passing through the respiratory system into the circulatory system, air pollutants are subsequently able to reach the brain. Among the potential mechanisms underlying particle-induced detrimental effects in the periphery and the central nervous system (CNS), increased oxidative stress, inflammation, mitochondrial dysfunction, microglial activation, disturbance of protein homeostasis, and ultimately, neuronal death are often postulated and concomitantly coincide with the main pathomechanisms of neurodegenerative processes. Other complementary mechanisms by which PM could mediate neurotoxicity and contribute to neurodegeneration remain unconfirmed. Furthermore, the question of how strong and proven air pollutants are as substantial adverse factors for neurodegenerative disease etiologies remains unsolved. This review highlights research advances regarding the issue of PM with an emphasis on neurodegeneration markers, symptoms, and mechanisms by which air pollutants could mediate damage in the CNS. Poor air quality and insufficient knowledge regarding its toxicity justify conducting scientific investigations to understand the biological impact of PM in the context of various types of neurodegeneration.

A critical review of the epidemiological evidence of effects of air pollution on dementia, cognitive function and cognitive decline in adult population

Dementia is arguably the most pressing public health challenge of our age. Since dementia does not have a cure, identifying risk factors that can be controlled has become paramount to reduce the personal, societal and economic burden of dementia. The relationship between exposure to air pollution and effects on cognitive function, cognitive decline and dementia has stimulated increasing scientific interest in the past few years. This review of the literature critically examines the available epidemiological evidence of associations between exposure to ambient air pollutants, cognitive performance, acceleration of cognitive decline, risk of developing dementia, neuroimaging and neurological biomarker studies, following Bradford Hill guidelines for causality. The evidence reviewed has been consistent in reporting associations between chronic exposure to air pollution and reduced global cognition, as well as impairment in specific cognitive domains including visuo-spatial abilities. Cognitive decline and dementia incidence have also been consistently associated with exposure to air pollution. The neuro-imaging studies reviewed report associations between exposure to air pollution and white matter volume reduction. Other reported effects include reduction in gray matter, larger ventricular volume, and smaller corpus callosum. Findings relating to ischemic (white matter hyperintensities/silent cerebral infarcts) and hemorrhagic (cerebral microbleeds) markers of cerebral small vessel disease have been heterogeneous, as have observations on hippocampal volume and air pollution. The few studies available on neuro-inflammation tend to report associations with exposure to air pollution. Several effect modifiers have been suggested in the literature, but more replication studies are required. Traditional confounding factors have been controlled or adjusted for in most of the reviewed studies. Additional confounding factors have also been considered, but the inclusion of these has varied among the different studies. Despite all the efforts to adjust for confounding factors, residual confounding cannot be completely ruled out, especially since the factors affecting cognition and dementia are not yet fully understood. The available evidence meets many of the Bradford Hill guidelines for causality. The reported associations between a range of air pollutants and effects on cognitive function in older people, including the acceleration of cognitive decline and the induction of dementia, are likely to be causal in nature. However, the diversity of study designs, air pollutants and endpoints examined precludes the attribution of these adverse effects to a single class of pollutant and makes meta-analysis inappropriate.

Sex-specific association between peripheral superoxide dismutase, BDNF and cognitive impairment in drug-naive first episode patients with schizophrenia

Patients with schizophrenia (SCZ) have cognitive impairments across several domains. Cognition decline is related to the complex interrelationship between brain-derived neurotrophic factor (BDNF) and redox system imbalance. However, the effect of sex on cognitive impairment and biomarkers has not been fully studied in patients with drug-naïve first episode (DNFE) SCZ. 327 DNFE SCZ patients and 391 healthy controls were recruited, and the levels of BDNF and malondialdehyde (MDA) and the activities of total SOD, Mn-SOD, CuZn-SOD enzymes were measured. Cognitive function was measured by using the Repeatable Battery for the Assessment of Neuropsychological status (RBANS) and clinical symptoms by the Positive and Negative Syndrome Scale (PANSS). Patients performed worse on most cognitive tasks than controls, but there was no significant sex difference in cognitive function between patients and controls. Further analysis showed that a sex difference in MDA was found in controls rather than patients, indicating that MDA levels in men were higher than those in women in controls. Moreover, the Mn-SOD was significantly correlated with attention, language and RBANS total scores only in male patients. Multiple linear regression analysis showed that the interaction between BDNF and Mn-SOD or SOD was associated with RBANS language index score in male patients. Our results suggest that the interrelationship of BDNF with antioxidant mechanisms may contribute to the pathological mechanisms underlying cognitive deficits only in male DNFE patients with SCZ, but not in female patients.

Interrelationships Between BDNF, Superoxide Dismutase, and Cognitive Impairment in Drug-Naive First-Episode Patients With Schizophrenia

The pathogenesis and etiology of schizophrenia (SCZ) remains unclear. Accumulating studies showed that complex interrelationships between brain-derived neurotrophic factor (BDNF) and an imbalanced redox system has a crucial role in the psychopathology of SCZ. However, the influence of the interrelationships of BDNF and superoxide dismutase (SOD) on cognitive impairment and clinical symptomatology in drug-naive first-episode (DNFE) SCZ patients has not been studied thoroughly. Serum BDNF levels, plasma total SOD, manganese-SOD (Mn-SOD), copper/zinc-containing SOD (CuZn-SOD) activities, and malondialdehyde (MDA) levels were measured in 327 DNFE patients with SCZ and 391 healthy controls. Cognitive functions were measured using the Repeatable Battery for the Assessment of Neuropsychological status (RBANS) and clinical symptoms were evaluated by the Positive and Negative Syndrome Scale (PANSS). Compared with the controls, the DNFE patients had increased activities of total SOD and CuZn-SOD, and reduced levels of BDNF and MDA. BDNF levels were positively correlated with CuZn-SOD activity in patients. In addition, we found that elevated Mn-SOD and CuZn-SOD activities were related to PANSS depression factor. Moreover, an interactive effect of BDNF levels and Mn-SOD activity was associated with attentional index score in the patients. Therefore, our findings suggested that interrelationships between BDNF and antioxidant mechanisms might underlie the pathological mechanisms of cognitive impairments and symptomatology in the DNFE patients with SCZ.

Oxidative Stress Indexes for Diagnosis of Health or Disease in Humans

Oxidative stress (OS) is the imbalance between oxidant and antioxidant molecules, in favor of oxidants, that causes aging and disease. Many studies have been published that demonstrate the relationship between OS and human health and disease; however, the following questions arise: (i) how are we sure that the OS is present in a biological process? (ii) Is the OS reported in the different investigations equivalent? (iii) What are the best oxidant and antioxidant markers for OS diagnosis? (iv) Can we establish the types and the intensity of the OS? (v) Does OS index could be useful for research and/or application in clinical medicine? In this regard, several indexes have been proposed to measure OS in humans relative to the state of health and disease, among which the following can be highlighted: Oxidative Stress Index (OSI), Tiol Ratios (-SH/TT, -SS/-SH, and-SS/TT), Glutathione Ratio (GSSG/GSH), Oxidative Stress Score (OSS), and OXY-index. Therefore, the aim of this review is to present the state of the art of knowledge about OS indexes for diagnosis of health or disease in humans. We searched for articles in English or Spanish in the PubMed/MEDLINE and Scopus electronic databases published up until May 2019. The keywords used were “oxidative stress,” “index,” and “oxidative stress index.” It was identified 11479 records in both databases, and 490 articles were analyzed. Our review suggests that all indexes analyzed allow diagnose and differentiate the OS related to human health and disease. Also, the studies on OSI, Oxy-score, and OSS indexes have proven to be reliable, practical, and with clinical utility. However, it is necessary to continue with longitudinal studies, especially assess the usefulness of the indexes in the clinical prognosis, and make comparative studies between the different indexes.

Superoxide dismutase activity and risk of cognitive decline in older adults: Findings from the Chinese Longitudinal Healthy Longevity Survey

BACKGROUND

The association between superoxide dismutase (SOD) activity and cognitive decline in older adults remains controversial.

OBJECTIVES

This study was designed to examine the association between plasma superoxide dismutase (SOD) activity and cognitive decline in older population.

METHOD

We analyzed the follow-up data from 2012 to 2014 waves of the Chinese Longitudinal Healthy Longevity Survey (CLHLS), a community-based longitudinal survey in Chinese longevity areas. A total of 1004 Chinese adults aged 60 years and older were included in this study. Plasma SOD activity was assessed. Cognitive function was evaluated by Mini-Mental State Examination (MMSE) in Chinese version. Modified Poisson regression was performed to investigate the association between plasma SOD activities with cognitive decline. Restricted cubic spline was performed to determine the dose-response relationship.

RESULTS

Participants in the highest quartile of SOD activity had an increased risk of cognitive decline compared with those in the lowest quartile (relative risk [RR] = 1.32, 95% confidence interval [CI]: 1.00-1.74, P = 0.051).Using cut-off points determined by Chi-square automatic interaction detector analysis (CHAID), the multivariable relative risks (RRs; 95% CI) for the lowest category, second highest, and the highest versus the third highest category of SOD activity were 0.56 (0.34-0.92), 1.26 (1.03-1.54), and 0.96 (0.70-1.31), respectively.

CONCLUSIONS

Higher SOD activity was associated with elevated risk of cognitive decline among Chinese older adults.

Tainted air: The link between pollution and Alzheimer's disease

In this issue of the Biomedical Journal, we learn how air pollution may contribute to cognitive decline and even increase risk for Alzheimer's disease. We also highlight original research documenting the body's response to infection with a common oral pathogen. Finally, we learn how a cellular antioxidant protein protects against mitochondrial dysfunction in Parkinson's disease.

Strategic procedure in three stages for the selection of variables to obtain balanced results in public health research

Multidisciplinary research in public health is approached using methods from many scientific disciplines. One of the main characteristics of this type of research is dealing with large data sets. Classic statistical variable selection methods, known as "screen and clean", and used in a single-step, select the variables with greater explanatory weight in the model. These methods, commonly used in public health research, may induce masking and multicollinearity, excluding relevant variables for the experts in each discipline and skewing the result. Some specific techniques are used to solve this problem, such as penalized regressions and Bayesian statistics, they offer more balanced results among subsets of variables, but with less restrictive selection thresholds. Using a combination of classical methods, a three-step procedure is proposed in this manuscript, capturing the relevant variables of each scientific discipline, minimizing the selection of variables in each of them and obtaining a balanced distribution that explains most of the variability. This procedure was applied on a dataset from a public health research. Comparing the results with the single-step methods, the proposed method shows a greater reduction in the number of variables, as well as a balanced distribution among the scientific disciplines associated with the response variable. We propose an innovative procedure for variable selection and apply it to our dataset. Furthermore, we compare the new method with the classic single-step procedures.

The emerging risk of exposure to air pollution on cognitive decline and Alzheimer's disease - Evidence from epidemiological and animal studies

As incidence of Alzheimer's disease (AD) and other neurodegenerative diseases rise, there is increasing interest in environmental factors which may contribute to disease onset and progression. Air pollution has been known as a major health hazard for decades. While its effects on cardiopulmonary morbidity and mortality have been extensively studied, growing evidence has emerged that exposure to polluted air is associated with impaired cognitive functions at all ages and increased risk of AD and other dementias in later life; this association is particularly notable with traffic related pollutants such as nitrogen dioxide, nitrous oxide, black carbon, and small diameter airborne solids and liquids known as particulate matter. The exact mechanisms by which air pollutants mediate neurotoxicity in the central nervous system (CNS) and lead to cognitive decline and AD remain largely unknown. Studies using animal and cell culture models indicate that amyloid-beta processing, anti-oxidant defense, and inflammation are altered following the exposure to constituents of polluted air. In this review, we summarize recent evidence supporting exposure to air pollution as a risk for cognitive decline at all ages and AD at later lifetime. Additionally, we review the current body of work investigating the molecular mechanisms by which air pollutants mediate damage in the CNS. Understanding of the neurotoxic effects of air pollution and its constituents is still limited, and further studies will be essential to better understand the cellular and molecular mechanisms linking air pollution and cognitive decline.

The complex association between the antioxidant defense system and clinical status in early psychosis

Oxidative stress is a pathophysiological mechanism potentially involved in psychiatric disorders. The objective of this study was to assess the relationship between total antioxidant status (TAS) and the functional status of patients with a first episode of psychosis at the onset of the disease. For this purpose, a sample of 70 patients aged between 9 and 17 years with a first episode of psychosis were followed up for a period of two years. Blood samples were drawn to measure TAS levels at three time points: at baseline, at one year, and at two years. Clinical symptoms and functioning were also assessed at the same time points using various scales. Linear regression analysis was performed to investigate the relationship between TAS and clinical status at each assessment, adjusting for potential confounding factors. The distribution of clinical variables was grouped in different percentiles to assess the dose-response in the relation between clinical variables and TAS. At baseline, patient's score on Children's Global Assessment Scale (CGAS) was directly and significantly associated with TAS with a monotonic increase in percentiles, and surprising this association was reversed after one and two years of follow-up with a monotonic decrease. In summary at the onset of the illness, TAS is positively related to clinical status, whereas as the illness progresses this correlation is reversed and becomes negative. This may be the result of an adaptive response.

Outdoor and indoor air quality and cognitive ability in young children

BACKGROUND

This study examined outdoor and indoor air quality at ages 9 months and 3 years and their association with cognitive ability at age 3 in England and Wales.

METHOD

Data from 8198 Millennium Cohort Study children were analysed using multilevel regression. Outdoor air quality was assessed with mean annual estimates of nitrogen dioxide (NO₂) levels within a standard small area (ward). Indoor air quality was measured with parent-reports of damp or condensation in the home and exposure to secondhand smoke in the home. Cognitive ability was assessed with the British Ability Scales Naming Vocabulary subscale and the Bracken School Readiness Assessment.

RESULTS

In adjusted models, consistent exposure to high levels of NO₂ at age 9 months and age 3 years was associated with lower verbal ability at age 3 years. Damp/condensation and secondhand smoke in the home at either age or at both ages were correlated with lower school readiness at age 3 years. Exposures to damp/condensation at age 3 years or at both ages and secondhand smoke at either age or at both ages were associated with lower verbal ability at age 3 years.

CONCLUSION

Young children's exposures to indoor damp or condensation and secondhand smoke are likely to be detrimental for their cognitive outcomes. However, there do not appear to be any short-term effects of NO₂.

High burden and frailty: association with poor cognitive performance in older caregivers living in rural areas

Abstract Introduction: Older caregivers living in rural areas may be exposed to three vulnerable conditions, i.e., those related to care, their own aging, and their residence context. Objective: To analyze the association of burden and frailty with cognition performance in older caregivers in rural communities. Method: In this cross-sectional survey, 85 older caregivers who cared for dependent elders were included in this study. Global cognition (Addenbrooke's Cognitive Examination – Revised; Mini Mental State Examination), burden (Zarit Burden Interview) and frailty (Fried's frailty phenotype) were assessed. All ethical principles were observed. Results: Older caregivers were mostly women (76.7%); mean age was 69 years. Cognitive impairment was present in 15.3%, severe burden in 8.2%, frailty in 9.4%, and pre-frailty in 52.9% of the older caregivers. More severely burdened or frail caregivers had worse cognitive performance than those who were not, respectively (ANOVA test). Caregivers presenting a high burden level and some frailty degree (pre-frail or frail) simultaneously were more likely to have a reduced global cognition performance. Conclusion: A significant number of older caregivers had low cognitive performance. Actions and resources to decrease burden and physical frailty may provide better cognition and well-being, leading to an improved quality of life and quality of the care provided by the caregivers.

Melatonin attenuated the brain damage and cognitive impairment partially through MT2 melatonin receptor in mice with chronic cerebral hypoperfusion

Background

Vascular cognitive impairment (VCI) is a spectrum of cognitive impairment caused by various chronic diseases including aging, hypertension, and diabetes mellitus. Oxidative and inflammatory reactions induced by chronic cerebral hypoperfusion (CHP) are believed to cause VCI. Melatonin is reported to possess anti-oxidation and anti-inflammation effects. This study was designed to investigate the effect and mechanisms of melatonin in CHP mice model.

Results

The behavioral function results revealed that CHP mice were significantly impaired when compared with the control. Melatonin improved the cognitive function, but the addition of MT2 receptor antagonist reversed the improvement. The IHC staining showed melatonin significantly improved WM lesions and gliosis in CHP mice. Again, the addition of MT2 receptor antagonist to melatonin worsened the WM lesion and gliosis. Similar results were also found for mRNA and protein expressions of oxidative reaction and inflammatory cytokines.

Materials and Method

Forty C57BL/6 mice were divided into four groups: Group 1: sham control; Group 2: CHP mice; Group 3: CHP with melatonin treatment; Group 4: CHP-melatonin and MT2 receptor antagonist (all groups n = 10). Working memory was assessed with Y–arm test at day-28 post-BCAS (bilateral carotid artery stenosis). All mice were sacrificed at day-30 post-BCAS. The immunohistochemical (IHC) staining was used for white matter (WM) damage and gliosis. The expression of mRNA and proteins about inflammatory and oxidative reaction were measured and compared between groups.

Conclusions

Partially through MT2 receptor, melatonin is effective for CHP-induced brain damage.

Exposure to air pollution and cognitive functioning across the life course--A systematic literature review

OBJECTIVES

Air pollution is associated with increased risk of respiratory, cardiovascular and cerebrovascular disease, but its association with cognitive functioning and impairment is unclear. The aim of this systematic review was to examine whether a relationship exists between these variables across the life course.

METHODS

We searched Web of Knowledge, Pubmed, SciVerse Scopus, CINAHL, PsychInfo and Science Direct up to October 2015 to identify studies that investigated the association between air pollution and performance on neurocognitive tests.

RESULTS

Variations in exposure assessment and outcome measures make meta-analysis impossible. Thirty one studies published between 2006 and 2015, from the Americas (n=15), Asia (n=5) and Europe (n=11), met the criteria for inclusion. Many showed weak but quantified relationships between various air pollutants and cognitive function. Pollution exposure in utero has been associated with increased risk of neuro-developmental delay. Exposure in childhood has been inversely associated with neuro-developmental outcomes in younger children and with academic achievement and neurocognitive performance in older children. In older adults, air pollution has been associated with accelerated cognitive decline.

CONCLUSIONS

The evidence to date is coherent in that exposure to a range of largely traffic-related pollutants has been associated with quantifiable impairment of brain development in the young and cognitive decline in the elderly. There is insufficient evidence at present to comment on consistency, in view of the different indices of pollution and end-points measured, the limited number of studies, and the probability at this stage of publication bias. However, plausible toxicological mechanisms have been demonstrated and the evidence as a whole suggests that vehicular pollution, at least, contributes to cognitive impairment, adding to pressure on governments and individuals to continue to reduce air pollution.

Association between oxidative stress and nutritional status in the elderly

Ageing is a dynamic and progressive process that is characterized by the occurrence of morphological, biochemical, functional and psychological changes in the organism. The aim of the present article is to provide updated concepts on oxidative stress, covering its importance in aging, as well as nutritional status and supplementation with antioxidants (substances that prevent or attenuate oxidation of oxidizable substrates, such as lipids, proteins, carbohydrates and deoxyribonucleic acid) in the geriatric population. Evidence suggests that there is an inverse relationship between oxidative stress and nutritional status in elderly individuals. Although an increase in oxidative stress in chronic diseases associated with aging has been proven, such as Parkinson's disease and Alzheimer's disease, up to now there has been no consistent clinical evidence proving the efficiency of supplementation with antioxidants against oxidative stress. In this context, supplementation is not recommended. On the other hand, the elderly should be encouraged to eat antioxidant foods, such as fruits and vegetables. Maintaining a normal weight (body mass index between 23 and 28 Kg/m(2)) should also be stimulated.

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.

Cognitive function, plasma MnSOD activity, and MnSOD Ala-9Val polymorphism in patients with schizophrenia and normal controls

Excessive reactive oxygen species are thought to produce oxidative damage that underlies neurodegeneration and cognitive impairment in several disorders including schizophrenia. The functional Ala-9Val polymorphism of the mitochondrial enzyme manganese superoxide dismutase (MnSOD), which detoxifies superoxide radicals to hydrogen peroxide, has been associated with schizophrenia. However, no study has reported its role in cognitive deficits of schizophrenia as mediated through MnSOD activity. We recruited 923 schizophrenic inpatients and 566 healthy controls and compared them on the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), plasma MnSOD activity, and the MnSOD Ala-9Val polymorphism. We assessed patient psychopathology using the Positive and Negative Syndrome Scale. We showed that the MnSOD Ala-9Val polymorphism may not contribute directly to the susceptibility to schizophrenia. The Ala variant was associated with worse attention performance among chronic schizophrenic patients but not among normal controls. Plasma MnSOD activity was significantly decreased in patients compared with that in normal controls. Moreover, MnSOD activity among the schizophrenic Ala allele carriers was correlated with the degree of cognitive impairments, especially attention and RBANS total score. We demonstrated an association between the MnSOD Ala-9Val variant and poor attention in schizophrenia. The association between higher MnSOD activity and cognitive impairment in schizophrenia is dependent on the MnSOD Ala-9Val polymorphism.

Plasma total antioxidant status and cognitive impairments in schizophrenia

Oxidative stress-induced damage to neurons may contribute to cognitive deficits during aging and in neurodegenerative disorders. Schizophrenia has a range of cognitive deficits that may evolve from oxidative stress, and this study examines this association of oxidative stress with cognitive deficits in schizophrenia. We recruited 296 chronic schizophrenia patients and 181 healthy control subjects and examined the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) and plasma total antioxidant status (TAS) in both groups. Schizophrenia symptoms were assessed using the positive and negative syndrome scale (PANSS). Our results showed that TAS levels were significantly lower in patients than controls (179.6 ± 81.0 U/ml vs. 194.8 ± 46.0 U/ml, p<0.05). Cognitive scores on the RBANS and nearly all of its five subscales (all p<0.001) except for the Visuospatial/Constructional index (p>0.05) were significantly lower in schizophrenia patients than normal controls. For the patients, TAS was inversely associated with some domains of cognitive deficits in schizophrenia, such as Attention and Immediate Memory. Our findings suggest that oxidative stress may be involved in the pathophysiology of schizophrenia, and its associated cognitive impairment.

Age-related sex differences in glutathione peroxidase and oxidative DNA damage in a healthy Mexican population

BACKGROUND AND OBJECTIVE

It has been proposed that women have an estrogen activity-linked biological antioxidant advantage and that this advantage is lost in the postmenopausal stage. The latter remains controversial. Our aim was to determine age-related sex differences in oxidative stress and oxidative DNA damage in a healthy Mexican population.

METHODS

A cross-sectional and comparative study was carried out in a convenience sample of 162 healthy subjects aged as follows: (1) 25-44 years (n = 35 women and 38 men), (2) 45-64 years (n = 41 women and 27 men), and (3) >or=65 years (n = 13 women and 8 men). We measured plasma lipoperoxides (LPO), superoxide dismutase (SOD), glutathione peroxidase (GPx), and DNA damage by comet assay.

RESULTS

We found greater activity of GPx in women than in men according to age increase (p < 0.05). This activity is maintained in old age in women. In contrast, men exhibited a significant diminution in GPx according to age increase. Similarly, we observed a greater percentage of cells without oxidative DNA damage in women in the 45-64-years age group and in the group of women aged >or=65 years.

CONCLUSIONS

Our findings suggest that women have a more efficient antioxidant activity than men, which has been linked with the greater longevity observed in women.

Circulating heat shock protein 70 in health, aging and disease

Background

Heat shock proteins (Hsp) are ubiquitously synthesised in virtually all species and it is hypothesised that they might have beneficial health effects. Recent studies have identified circulating Hsp as an important mediator in inflammation - the effects of low-grade inflammation in the aging process are overwhelming. While much is known about intracellular Hsp70, scant data exist on circulating Hsp70 in the aging context. Therefore, the objectives of this study were to investigate the effect of age and disease on circulating Hsp70 and, in particular, to evaluate the association between circulating Hsp70 and inflammatory parameters.

Results

Serum Hsp70, Interleukin (IL) -10, IL-6 and Tumor Necrosis Factor (TNF) alpha concentrations were determined in 90 hospitalised geriatric patients (aged 83 ± 6 years) and in 200 community-dwelling control subjects (100 elderly, aged 74 ± 5 years, and 100 young, aged 23 ± 3 years). In the community-dwelling elderly, serum Hsp70 and IL-10 concentrations were significantly lower and IL-6 was significantly higher when compared to healthy young control subjects. Elderly patients presenting inflammation (CRP serum levels ≥5 mg/L) showed significantly (p = 0.007) higher Hsp70 values; and Hsp70 correlated positively (p < 0.001) with IL-6 and CRP, but not with TNF-alpha or IL-10. A significant association was also noted between Hsp70 levels and the degree of dependency and cognitive decline in geriatric patients.

Conclusions

The present data provide new evidence that serum concentration of Hsp70 decreases with age in a normal population. Our study also shows that higher levels of Hsp70 are associated with inflammation and frailty in elderly patients.

Effect of a self-care program on oxidative stress and cognitive function in an older Mexican urban-dwelling population

OBJECTIVE

To determine the effect of a self-care program on oxidative stress (OxS) and cognitive function in an older, Mexican, urban-dwelling population.

DESIGN

A longitudinal and pre-experimental study was carried out in a sample of 79 older healthy, urban-dwelling individuals residing in Mexico City, (62 females and 17 males), of which 71 of them (59 women and 12 males) complied with the entire self-care program.

MEASUREMENTS

We measured OxS, cognitive function, the Nagi Disability Scale of physical task functioning, and Instrumental Activities of Daily Living (IADL) prior to and after 2 years of intervention with an active aging program.

RESULTS

All older persons adopted healthy, self-care-based lifestyles according to the active aging program to which they were trained, which was associated with a statistically significant improvement of OxS and cognitive function markers on comparing pre- and post-community intervention data.

CONCLUSIONS

Our findings suggest that self-care-based healthy lifestyles programs can improve the oxidative stress and cognitive function in urban-dwelling elderly population.

Biomarkers of Psychological Stress in Health Disparities Research

Psychological stress can contribute to health disparities in populations that are confronted with the recurring stress of everyday life. A number of biomarkers have been shown to be affected by psychological stress. These biomarkers include allostatic load, which is a summary measure of the cumulative biological burden of the repeated attempts to adapt to daily stress. Allostatic load includes effects on the hypothalamic-pituitary axis, the sympathetic nervous system and the cardiovascular system. These in turn affect the immune system via bidirectional signaling pathways. Evidence is also building that psychological stress, perhaps via heightened inflammatory states, can increase oxidative stress levels and DNA damage. The inter-relationships of ethnicity, genotype, gene expression and ability to adequately mitigate stress response are just starting to be appreciated. The need to conduct these studies in disadvantaged populations is clear and requires methods to address potential logistical barriers. Biomarkers can help characterize and quantify the biological impact of psychological stress on the etiology of health disparities.

Glutathione levels in blood from ataxia telangiectasia patients suggest in vivo adaptive mechanisms to oxidative stress

OBJECTIVE

To evaluate an in vivo pro-oxidant state in patients with ataxia telangiectasia (AT).

METHODS

A set of oxidative stress endpoints were measured in 9 AT homozygotes, 16 AT heterozygotes (parents) and 83 controls (grouped in age ranges as for patients and parents, respectively). The following analytes were measured: (a) leukocyte 8-hydroxy-2'-deoxyguanosine (8-OHdG); (b) blood glutathione (GSSG and GSH); and (c) plasma levels of glyoxal (Glx) and methylglyoxal (MGlx).

RESULTS

AT patients displayed a significant decrease in blood GSSG (p=0.012) and in MGlx plasma concentrations (p=0.012). A non-significant decrease in the GSSG:GSH ratio (p=0.1) and a non-significant increase in 8-OHdG and Glx levels were observed in AT patients vs. young controls (age range 4-35 years). AT heterozygotes failed to display any significant changes vs. adult controls (age range 36-68 years).

CONCLUSION

No significant increase in oxidative stress biomarkers was detected in blood from AT patients. The decrease in GSSG and MGlx levels in AT patients may suggest an adaptive response to a pro-oxidant state in AT-related target organs.