Visto que o estresse oxidativo está intimamente relacionado com a progressão da demência, este se apresenta como um possível alvo terapêutico a fim de preservar as funções cognitivas. No mesmo sentido, estudos mostram o papel antioxidante do selênio, mineral que atua por meio das selenoproteínas, com destaque para a família de enzimas antioxidantes glutationa peroxidase (GPx) e a selenoproteína responsável pelo transporte de selênio, a selenoproteína P (SePP). Entretanto, diferentes genótipos dos genes que codificam essas selenoproteínas podem refletir em diferentes respostas diante de intervenções alimentares. Assim, este trabalho teve como objetivo verificar os efeitos da suplementação com castanha-do-brasil sobre o estresse oxidativo em pacientes com comprometimento cognitivo leve (CCL) e verificar sua relação com os polimorfismos rs1050450 (Pro198Leu) no gene da GPx1, rs3877899 e rs7579 no gene da selenoproteína P. Participaram do estudo 31 indivíduos com CCL, voluntários, de ambos os sexos, frequentadores do Ambulatório de Memória do Idoso do Serviço de Geriatria da Faculdade de Medicina da Universidade de São Paulo, com idade igual ou superior a 60 anos, que foram distribuídos aleatoriamente entre os grupos Castanha e Controle. O grupo Castanha recebeu uma unidade de castanha-do-brasil por dia durante seis meses. Foram avaliados os seguintes marcadores: determinação de selênio no plasma e nos eritrócitos, atividade da GPx eritrocitária, avaliação dos níveis de oxygen radical absorbance capacity (ORAC) e de malondialdeído (MDA) plasmáticos, perfil lipídico sérico e expressão gênica de GPx1 e SePP. Além disso, os participantes foram submetidos à avaliação cognitiva e genotipados quanto aos polimorfismos rs1050450, rs3877899 e rs7579. Cada unidade de castanha-do-brasil forneceu 288,75µg de selênio. Dentre os 31 participantes selecionados, apenas 20 concluíram o estudo, e observou-se que, antes da intervenção, os grupos de estudo não apresentavam diferença quanto aos níveis de selênio no plasma e no eritrócito, bem como na atividade da GPx e nos níveis plasmáticos de ORAC e de MDA. Porém, após a suplementação, verificou-se aumento significativo no selênio plasmático (290,6±74,6) e eritrocitário (574,6±181,4) e na atividade da GPx (59,55±20,79) no grupo Castanha, diferente do grupo Controle (47,48±11,7 no plasma; 33,5±16,1 no eritrócito; 42,54±13,05 atividade da GPx). Em relação ao MDA, verificou-se que ambos os grupos apresentaram aumento após a intervenção, porém não significativo. No caso do ORAC, não se verificou alteração entre os grupos após os seis meses. O escore CERAD, que avalia desempenho cognitivo, não foi diferente entre os grupos após o tratamento, entretanto as mudanças observadas na fluência verbal e na praxia construtiva ao longo do acompanhamento foram mais favoráveis no grupo Castanha. A frequência dos genótipos de referência foram 40% para Pro198Leu, 55% para rs7579 e 60% para rs3877899. Não foram identificadas diferenças entre os níveis de selênio, de atividade da GPx, de MDA e de ORAC entre os genótipos, porém em análise multivariada verificou-se que o alelo variante do Pro198Leu se relacionou com aumento de 0,613 dp na concentração de selênio no plasma no baseline. A influência dos polimorfismos na resposta à intervenção com castanha-do-brasil foi avaliada nos 11 participantes do grupo Castanha, e observou-se que os genótipos não influenciaram na resposta quanto os níveis de selênio plasmático e eritrocitário, bem como de MDA. Entretanto, quanto à atividade da GPx, embora todos os genótipos tenham apresentado aumento após a intervenção, isso não foi significativo para o genótipo dominante do rs7579 e para o variante do rs3877899. A expressão de GPx1 e de SePP também foi diferente entre os genótipos: indivíduos com alelo variante do Pro198Leu apresentaram redução da expressão da GPx1, enquanto carreadores do genótipo homozigoto dominante tiveram aumento. Também percebeu-se que a expressão da SePP foi reduzida em todos os genótipos, entretanto essa mudança foi mais relevante para os genótipos variantes do Pro198Leu e rs7579 e para o genótipo GG do rs3877899. A partir desses resultados, concluiu-se que o consumo de apenas uma castanha-do-brasil diariamente, durante seis meses, é suficiente para recuperar o estado nutricional relativo ao selênio, e isso parece ter efeitos positivos sobre a cognição em idosos com CCL. Além disso, observou-se que o polimorfismo Pro198Leu no gene da GPx1 parece influenciar o estado nutricional quanto ao selênio, bem como a expressão de GPx, enquanto que os polimorfismos rs7579 e rs3877899 parecem não influenciar, de maneira significativa, o metabolismo de selênio frente ao consumo de castanha-do-brasil. / Since oxidative stress is closely related to progression of dementia, the antioxidant system may be a potential therapeutic target to preserve cognitive function. In this way, studies show the antioxidant role of selenium, which plays as selenoproteins especially glutathione peroxidase (GPx) family and selenoprotein P (SePP). However, different genotypes of selenoprotein genes may result in different response to dietary intake. Therefore, this work aimed to verify the effects of Brazil nuts intake on oxidative stress and the role of the polymorphisms rs1050450 (Pro198Leu) in GPx1 gene and rs7579 and rs3877899 in SePP gene in mild cognitive impairment (MCI) patients. Study subjects comprised 31 voluntary patients with MCI who attended the Memory and Aging Unit of the Geriatrics Division, University of São Paulo Medical School (Brazil). They were randomly assigned to ingestion of Brazil nuts or to the control group. Brazil nuts group received one nut daily during six months. The following parameters were analysed: selenium concentration in plasma and erythrocyte, GPx activity in erythrocyte, plasmatic levels of oxygen radical absorbance capacity (ORAC) and of malondialdedyde (MDA), serum lipid profile. Besides, we evaluated cognitive performance and the patients were genotyped to rs1050450, rs3877899 e rs7579 polymorphisms. Each Brazil nut provided 288.75µg of selenium. Among 31 enrolled participants, only 20 finished the study. No differences regarding selenium levels, GPx activity, ORAC and MDA levels were observed at baseline between groups. However, after treatment, we observed significant increase in selenium in plasma (290.6±74.6) and in erythrocyte (574.6±181.4) and in GPx activity (59.55±20.79) in treated group, unlike control group (47.48±11.70 selenium in plasma; 33.5±16.1 selenium in erythrocyte; 42.54±13.05 GPx activity). Although not significant, MDA level increased after 6 months in both groups and ORAC levels were not different across time. CERAD total score was not different across time between groups, however changes in verbal fluency and constructional praxis subtests across time were significantly more favorable on the supplemented group when compared with control group. The frequency of dominant genotypes for Pro198Leu, rs7579 and rs3877899 were 40%, 55% and 60%, respectively. We did not observe differences regarding to selenium ORAC and MDA levels and GPx activity among genotypes, however after linear regression analysis the presence of variant allele of Pro198Leu was associated with an increase of 0.613 SD in selenium plasma level at baseline. The effect of polymorphisms in response to Brazil nut intake was analysed in Brazil nut group, and we observed that sele nium and MDA levels were not affected by polymorphisms. However although GPx activity increased in all genotype groups, this was not significant in dominant genotype of rs7579 and variant genotypes of rs3877899. GPx1 and SePP expression was also different among groups across time: variant allele of Pro198Leu presented decreased expression of GPx1 while dominant homozygous presented increase of expression. We also observed that SePP expression was reduced in all genotypes, but his was more important in variant genotypes of Pro198Leu and rs7579 and in GG genotype of rs3877899. From these results, we can conclude that consumption of only one Brazil nut is enough to restore selenium status, and this may be positive effects on cognition performance. Furthermore we observed that Pro198Leu polymorphism may influence selenium nutritional status and GPx activity whereas rs7579 and rs3877899 polymorphisms did not have an effect on selenium metabolism after Brazil nut intake.

The proportion of older adults living with cognitive impairments is increasing rapidly. This shift will likely increase mortality rates, reduce perceived quality of life, and cause economic burden to patients and health care systems. Currently evidence of highly effective and noninvasive interventions that prevent or slow the onset of cognitive impairment are limited. This study aims to better understand what drives cognitive aging variability among musicians versus non-musicians. Music playing has been shown to improve brain and cognitive functions by engaging networks of brain areas, simultaneously involving cortical mechanisms associated with executive, high-level cognitive and motor functions, and multiple sensory systems. Literature suggests strong correlations between cognition and music ability. However, studies in the past have not concretely operationalized music training. Here we test the general hypothesis that music training improves neural mechanisms associated with core cognitive functions (e.g. working-memory and attention). A multi-source study was designed to control level of music involvement and genre by examining professional, classically trained orchestral musicians, establishing cognitive and neuropsychological profiles in an effort to better understand the potential for music training to protect older adults from cognitive decline. Specific hypotheses involved attentional inhibition theory and increased ability of musicians to perform attention and working memory tasks. Twenty-nine professional musicians were recruited who completed five neuropsychological exams. The scalp electrophysiological signals from 14 channels were recorded wirelessly while each musician performed a modified delayed match-to-sample task, imagination of music playing, and resting states. Musicians completed neuropsychological screening (MoCA) a music and life span questionnaire as well. Musicians tested above normative ranges in cognitive ability indicated through MoCA. Musicians’ scores were compared with average or normative scores of participants at similar ages in previous studies using the same measures and current musicians performed significantly faster and more accurately on four of five neuropsychological measures. Regression and ANCOVA showed strong positive correlations between theta oscillation in bilateral frontal sites (F3, F4) and both number of years of private music lessons and number of hours of music practice. Correlations between EEG recordings taken during music imagination exercise at posterior (01, 02) sites and the number of years of private music lessons participants took, the age participant started to take music lessons and the number of years they played their musical instrument were found. Current new findings reveal that professional musician’s cognitive scores and neural activity are associated with superior cognitive ability via enhancement of neural mechanisms of current target material and inhibition of distractions. Music training is apromising noninvasive method to control cognitive challenge, which merits further research to determine how it can be used as a beneficial cognitive training method for aging individuals. Future studies should examine neuro-cognitive differences between professional musicians and individuals with lower levels of music involvement to examine dose effects of music or the amount of music needed to protect aging adults from cognitive decline.

The Mediterranean diet (Medi) has been highlighted as the golden diet rich in protective properties associated with cognitive- and emotional health. The foundation of the Medi comprises vegetables, fruits, nuts and seeds, legumes, and extra virgin olive oil. Research has been conducted in both holistic dietary approach and single nutrient approach regarding the impact of nutrition and diet, in this case, the Medi‟s effect on brain health. This review aims to give an up to date overview of the Mediterranean diet, outline some of the diet's abundant nutrients, and discuss studies linking the nutrient's potential effect on depression, cognitive decline, dementia, and brain structure and function. In addition, this review will attempt to assess whether the Medi as a whole or if a single nutrient approach is accountable for the health-promoting findings. Furthermore, the gut-brain axis, and other potential underlying mechanisms involved in the modulation of food- and nutrient intake and their effects on the brain, will be outlined. A diet high in fruit-, vegetable-, polyunsaturated fatty acid-, and monounsaturated fatty acid content has great power for health-maintenance and decreases the risk of suffering cognitive decline, dementia, and potentially depression. More randomized controlled trials are however eagerly awaited to give more substance to previous findings.

Decreased amyloid-ß42 (Aß42), increased total tau (t-tau) and phosphorylated tau (p-tau) in cerebrospinal fluid (CSF) reflect histopathological core changes in the most common dementia disorder, Alzheimer’s disease (AD). They discriminate AD from healthy controls and predict conversion to AD with a relatively high accuracy. Memantine, an uncompetitive NMDA-receptor antagonist, is indicated for symptomatic treatment of AD. The first aim of this thesis was to investigate effects of memantine on CSF concentrations of Aβ42, tau and p-tau. Secondly, the aim was to explore the relation between these CSF biomarkers and retention of the amyloid biomarker Pittsburgh compound B using positron emission tomography (PIB PET), regional glucose metabolism measured with 18Fluoro-2-deoxy-d-glucose (FDG) PET and neuropsychological test performance. The third aim was to investigate their possible utility as predictors of future rate of AD dementia deterioration. All patients in the studies were recruited from the Memory Clinic, Uppsala University Hospital. In study I CSF p-tau concentrations in 11 AD patients were reduced after twelve months treatment with memantine, indicating that this compound may affect a key pathological process in AD. Results from study II showed that the concentrations of CSF Aß42 are lower in PIB+ patients than in PIB- patients, and that the PIB retention was stable during 12 months. In study III 10 patients with the diagnoses AD (6 PIB+/4 PIB-) and 8 subjects (1 PIB+/7 PIB-) with frontotemporal dementia were included. PIB+ patients had lower psychomotor speed measured by performance on the Trail Making Test A and impaired visual episodic memory compared to the PIB- patients. The initial clinical diagnoses were changed in 33% of the patients (6/18) during follow-up. Study IV is the first-ever report of an association between high CSF tau and dying in severe dementia. These 196 AD patients were followed up to nine years after baseline lumbar puncture. Moreover, CSF t-tau concentrations above median was associated with an increased risk of rapid cognitive decline (OR 3.31 (95% CI 1.53-7.16), independently of baseline functional stage. Thus, a clear association between high levels of CSF t-tau and p-tau and a more aggressive course of the disease was shown.

Despite considerable debate surrounding an age associated cognitive decline in non-demented elders, recent studies indicate that changes attributable to normal aging affect cognitive processes and fluid abilities. Additionally, studies indicate that factors such as physical illness, depression, neurological damage, medication side effects, drug interactions, and the effects of surgery and anesthesia may also cause varying degrees of cognitive impairment. Impairment of cognitive function is known to affect treatment and rehabilitation outcomes for older persons, and increase their likelihood of institutionalization. Although proper screening and identification of cognitive deficits in geriatric patients are crucial in developing treatment plans, there is evidence in the medical and nursing literature that cognitive decline in older non-demented patients is often not identified. Proper screening in this case, refers not only to whether or not clinicians engage in assessment behavior, but that they adhere to evidence-based practices and utilize standardized instruments which can identify the type, extent, and implications of the cognitive deficits. This study used an exploratory, non-experimental design and the population of interest consisted of occupational therapists providing physical rehabilitation to patients >65 years of age in the United States. The Ecological Systems Model was chosen as the theoretical framework, because it depicts human behavior as the product of the interaction between the individual's personal attributes and the physical and social environment in which the individual functions. Given the changes in health care, and the limits imposed by third party payers, it would seem important to inquire as to the effect of personal and practice contexts on therapists' assessment practices in geriatric rehabilitation. Although results of the study indicate that factors in the practice context are stronger predictors of therapists' use of standardized cognitive screening and assessment instruments, the study supports principles of Ecological Systems Models in that both practice and personal contexts contribute to therapists' assessment practices.

Changes in both sleep architecture and cognition are common with age. Typically these changes have a negative connotation: sleep fragmentation, insomnia, and deep sleep loss as well as forgetfulness, lack of focus, and even dementia and Alzheimer’s disease. Research has shown that psychosocial stressors, such as isolation from family and friends or loss of a loved one can also have significant negative effects on sleep architecture and cognitive capabilities. This leaves the elderly in a particularly vulnerable situation: suffering from cognitive decline and sleep dysregulation already, and more likely to respond negatively to psychosocial stressors. Taking all of these factors into account, it’s surprising that little research has been done to elucidate the mechanisms behind aged subjects’ enhanced vulnerability to new onset psychosocial stress. Our lab embarked on a series of studies to test the effects of age and psychosocial stress on sleep architecture and cognition. Our first study measured sleep stages in young adult and aged F344 rats during their resting and active periods. Animals were behaviorally characterized on the Morris water maze and gene expression profiles of their parietal cortices were taken. We confirmed previous studies that found impaired cognition and decreased resting deep sleep with age. However, it was increased active deep sleep that correlated best with poor cognitive performance. In the second study rats were subjected to immobilization (restraint stress) immediately preceding their final water maze task. Hippocampi were prepared for synaptic electrophysiology and trunk blood was taken for corticosterone measurement after post-stress sleep architecture data was collected. Young subjects responded to acute stress with decreased cognition, elevated CORT levels and altered sleep architecture. In contrast, stressed aged subjects were statistically indistinguishable from control aged subjects, suggesting that aged rats are less responsive to an acute psychosocial stress event. Together, these studies suggest that alleviating sleep dysregulation could therapeutically benefit cognition psychosocial stress resilience.

No description available.

Individuals in modern Western societies are experiencing increasing sedentary lifestyles, overindulgence of high fat, high-sugar diets, and extremely sterilized conditions, putting immense pressure on researchers and clinicians alike to come up with viable treatments for conditions implicated with an aging society. Emerging research have published the benefits of IMS and metabolic switching in a variety of neuroprotective, cellular stress resistance, and neuroplasticity pathways in animal models and clinical results from randomized trials of IMS regimens with susceptible human populations are soon to be published. The application of genome editing and next-generation sequencing (NGS) strategies to clinical and neurodegenerative research continues to elucidate the relationship between a patient’s specific genetic background and modern environmental stressors towards disease pathology. This study attempts to utilize novel CRISPR/Cas9 strategies to introduce targeted gene edits and explores the role of reduced ketone-body synthesis/metabolism with 3-hydroxymethyl-3-methylglutaryl-CoA lyase HMGCL KO, in the therapeutic and neuroprotective potential of intermittent metabolic switching in 3xTg mice, genetically predisposed for Alzheimer pathology. IMS-mediated attenuation of hippocampal spatial memory deficits was confirmed in 5-month-old 3xTg mice using Morris Water Maze and Aβ1-40, Aβ1-42, total tau and p-tau levels were calculated accordingly. Mice receiving time-restricted feeding (TRF) and caloric restriction (CR) regardless of KO performed better in the hippocampal-dependent spatial memory test and ELISA analysis of CSF revealed reduced p-tau levels of 3xTg WT TRF + CR mice relative to WT control or the two experimental groups. Overall, genetic modifications of key metabolic enzymes highlight the variable therapeutic results of the glucose to ketone metabolic switch on cognitive deficits depending on an organism’s genetic background.

Visto que o estresse oxidativo está intimamente relacionado com a progressão da demência, este se apresenta como um possível alvo terapêutico a fim de preservar as funções cognitivas. No mesmo sentido, estudos mostram o papel antioxidante do selênio, mineral que atua por meio das selenoproteínas, com destaque para a família de enzimas antioxidantes glutationa peroxidase (GPx) e a selenoproteína responsável pelo transporte de selênio, a selenoproteína P (SePP). Entretanto, diferentes genótipos dos genes que codificam essas selenoproteínas podem refletir em diferentes respostas diante de intervenções alimentares. Assim, este trabalho teve como objetivo verificar os efeitos da suplementação com castanha-do-brasil sobre o estresse oxidativo em pacientes com comprometimento cognitivo leve (CCL) e verificar sua relação com os polimorfismos rs1050450 (Pro198Leu) no gene da GPx1, rs3877899 e rs7579 no gene da selenoproteína P. Participaram do estudo 31 indivíduos com CCL, voluntários, de ambos os sexos, frequentadores do Ambulatório de Memória do Idoso do Serviço de Geriatria da Faculdade de Medicina da Universidade de São Paulo, com idade igual ou superior a 60 anos, que foram distribuídos aleatoriamente entre os grupos Castanha e Controle. O grupo Castanha recebeu uma unidade de castanha-do-brasil por dia durante seis meses. Foram avaliados os seguintes marcadores: determinação de selênio no plasma e nos eritrócitos, atividade da GPx eritrocitária, avaliação dos níveis de oxygen radical absorbance capacity (ORAC) e de malondialdeído (MDA) plasmáticos, perfil lipídico sérico e expressão gênica de GPx1 e SePP. Além disso, os participantes foram submetidos à avaliação cognitiva e genotipados quanto aos polimorfismos rs1050450, rs3877899 e rs7579. Cada unidade de castanha-do-brasil forneceu 288,75µg de selênio. Dentre os 31 participantes selecionados, apenas 20 concluíram o estudo, e observou-se que, antes da intervenção, os grupos de estudo não apresentavam diferença quanto aos níveis de selênio no plasma e no eritrócito, bem como na atividade da GPx e nos níveis plasmáticos de ORAC e de MDA. Porém, após a suplementação, verificou-se aumento significativo no selênio plasmático (290,6±74,6) e eritrocitário (574,6±181,4) e na atividade da GPx (59,55±20,79) no grupo Castanha, diferente do grupo Controle (47,48±11,7 no plasma; 33,5±16,1 no eritrócito; 42,54±13,05 atividade da GPx). Em relação ao MDA, verificou-se que ambos os grupos apresentaram aumento após a intervenção, porém não significativo. No caso do ORAC, não se verificou alteração entre os grupos após os seis meses. O escore CERAD, que avalia desempenho cognitivo, não foi diferente entre os grupos após o tratamento, entretanto as mudanças observadas na fluência verbal e na praxia construtiva ao longo do acompanhamento foram mais favoráveis no grupo Castanha. A frequência dos genótipos de referência foram 40% para Pro198Leu, 55% para rs7579 e 60% para rs3877899. Não foram identificadas diferenças entre os níveis de selênio, de atividade da GPx, de MDA e de ORAC entre os genótipos, porém em análise multivariada verificou-se que o alelo variante do Pro198Leu se relacionou com aumento de 0,613 dp na concentração de selênio no plasma no baseline. A influência dos polimorfismos na resposta à intervenção com castanha-do-brasil foi avaliada nos 11 participantes do grupo Castanha, e observou-se que os genótipos não influenciaram na resposta quanto os níveis de selênio plasmático e eritrocitário, bem como de MDA. Entretanto, quanto à atividade da GPx, embora todos os genótipos tenham apresentado aumento após a intervenção, isso não foi significativo para o genótipo dominante do rs7579 e para o variante do rs3877899. A expressão de GPx1 e de SePP também foi diferente entre os genótipos: indivíduos com alelo variante do Pro198Leu apresentaram redução da expressão da GPx1, enquanto carreadores do genótipo homozigoto dominante tiveram aumento. Também percebeu-se que a expressão da SePP foi reduzida em todos os genótipos, entretanto essa mudança foi mais relevante para os genótipos variantes do Pro198Leu e rs7579 e para o genótipo GG do rs3877899. A partir desses resultados, concluiu-se que o consumo de apenas uma castanha-do-brasil diariamente, durante seis meses, é suficiente para recuperar o estado nutricional relativo ao selênio, e isso parece ter efeitos positivos sobre a cognição em idosos com CCL. Além disso, observou-se que o polimorfismo Pro198Leu no gene da GPx1 parece influenciar o estado nutricional quanto ao selênio, bem como a expressão de GPx, enquanto que os polimorfismos rs7579 e rs3877899 parecem não influenciar, de maneira significativa, o metabolismo de selênio frente ao consumo de castanha-do-brasil. / Since oxidative stress is closely related to progression of dementia, the antioxidant system may be a potential therapeutic target to preserve cognitive function. In this way, studies show the antioxidant role of selenium, which plays as selenoproteins especially glutathione peroxidase (GPx) family and selenoprotein P (SePP). However, different genotypes of selenoprotein genes may result in different response to dietary intake. Therefore, this work aimed to verify the effects of Brazil nuts intake on oxidative stress and the role of the polymorphisms rs1050450 (Pro198Leu) in GPx1 gene and rs7579 and rs3877899 in SePP gene in mild cognitive impairment (MCI) patients. Study subjects comprised 31 voluntary patients with MCI who attended the Memory and Aging Unit of the Geriatrics Division, University of São Paulo Medical School (Brazil). They were randomly assigned to ingestion of Brazil nuts or to the control group. Brazil nuts group received one nut daily during six months. The following parameters were analysed: selenium concentration in plasma and erythrocyte, GPx activity in erythrocyte, plasmatic levels of oxygen radical absorbance capacity (ORAC) and of malondialdedyde (MDA), serum lipid profile. Besides, we evaluated cognitive performance and the patients were genotyped to rs1050450, rs3877899 e rs7579 polymorphisms. Each Brazil nut provided 288.75µg of selenium. Among 31 enrolled participants, only 20 finished the study. No differences regarding selenium levels, GPx activity, ORAC and MDA levels were observed at baseline between groups. However, after treatment, we observed significant increase in selenium in plasma (290.6±74.6) and in erythrocyte (574.6±181.4) and in GPx activity (59.55±20.79) in treated group, unlike control group (47.48±11.70 selenium in plasma; 33.5±16.1 selenium in erythrocyte; 42.54±13.05 GPx activity). Although not significant, MDA level increased after 6 months in both groups and ORAC levels were not different across time. CERAD total score was not different across time between groups, however changes in verbal fluency and constructional praxis subtests across time were significantly more favorable on the supplemented group when compared with control group. The frequency of dominant genotypes for Pro198Leu, rs7579 and rs3877899 were 40%, 55% and 60%, respectively. We did not observe differences regarding to selenium ORAC and MDA levels and GPx activity among genotypes, however after linear regression analysis the presence of variant allele of Pro198Leu was associated with an increase of 0.613 SD in selenium plasma level at baseline. The effect of polymorphisms in response to Brazil nut intake was analysed in Brazil nut group, and we observed that sele nium and MDA levels were not affected by polymorphisms. However although GPx activity increased in all genotype groups, this was not significant in dominant genotype of rs7579 and variant genotypes of rs3877899. GPx1 and SePP expression was also different among groups across time: variant allele of Pro198Leu presented decreased expression of GPx1 while dominant homozygous presented increase of expression. We also observed that SePP expression was reduced in all genotypes, but his was more important in variant genotypes of Pro198Leu and rs7579 and in GG genotype of rs3877899. From these results, we can conclude that consumption of only one Brazil nut is enough to restore selenium status, and this may be positive effects on cognition performance. Furthermore we observed that Pro198Leu polymorphism may influence selenium nutritional status and GPx activity whereas rs7579 and rs3877899 polymorphisms did not have an effect on selenium metabolism after Brazil nut intake.

The topic of this thesis is how the decline of cognitive abilities and memory functioning in elder people can be assisted by external memory aids. This issue was approached through a combination of methods. The starting point was a literature review of two approaches to the study of memory – the traditional where memory functions are located in the brain and the situated where remembering transcends over external resources, and by a literature review on declining memory abilities in elderly people. An ethnographic study of everyday remembering in an older population, aged from 72 to 91, found many instances of the spontaneous use of the environment to support a declining memory ability, which in turn suggest that the traditional approach to memory research is of limited value when studying everyday memory abilities in older people. A study on existing memory aids, as well as memory aids currently under development in research laboratories showed that these technologies are primarily based on an explicit or implicit traditional view of memory that disregard several aspects of remembering in the natural world. It is therefore suggested that future development of memory aids could fruitfully benefit from a distributed and situated approach, where the individuals‘ current use of external memory aids are used as the starting point, with the goal of extending and amplifying methods and artefacts already spontaneously in use.