Identification of modifiable risk factors for Alzheimer’s disease (AD) is crucial in order to diminish suffering from this devastating disease. The aim of this thesis was to investigate if different aspects of glucose metabolism, insulin, fatty-acid composition or other vascular risk factors predict the future development of AD and dementia. This thesis is based on the Uppsala Longitudinal Study of Adult Men (ULSAM) cohort, which started in 1970. A total of 2322 men at age 50 were examined with focus on vascular risk factors. The cohort was re-examined at ages 60, 71, 77, 82 and 88. Incident diagnoses of AD, vascular dementia, other dementias and cognitive impairment were assessed in 2005–2010. The risk of AD was increased in subjects with lower early insulin response measured with both an intravenous glucose tolerance test at 50 years and an oral glucose tolerance test at 71 years of age. The presence of vascular risk factors such as hypertension, obesity, hypercholesterolemia and smoking increased the risk of future vascular dementia but not of AD. Furthermore, saturated fatty acids at midlife were inversely associated with risk of AD. No evidence of a protective effect of omega-3 fatty acids against dementia was found. The susceptibility allele, APOE ε4, was the strongest individual risk factor. APOE ε4 carriers with vascular risk factors had the greatest risk of developing dementia. Low insulin response was a risk factor for AD mainly in APOE ε4 non-carriers. Disturbances in insulin and glucose metabolism, vascular risk factors and fatty acids are linked differentially to the pathogenesis of AD and vascular dementia. These observations should be considered when future clinical approaches are planned to prevent and postpone the onset of dementia. / ULSAM

Hormone replacement therapy (HRT) has been studied as a protective factor for cognitive decline and dementia. However, study findings have been inconsistent. Variation in study findings may be due to differences in study designs, small sample size, exposure ascertainment, diagnostic procedures, and inclusion of relevant risk and confounding factors. Moreover, there may be significant differences between the characteristics of women choosing to use HRT and those opting not to use the therapy. Using a large-scale, population-based, cohort study, we examined the relationship between HRT and cognition while paying particular attention to moderating and confounding factors. The main outcomes of interest were to assess differences in risk for cognitive impairments and dementia between HRT user and never user groups; examine HRTs impact on age of onset of dementia; and explore the relationship between duration of HRT and cognitive decline. Logistic regression and Cox Proportional Hazards models were used to test HRT as a predictor for cognitive impairments, Alzheimers disease and vascular dementia, as well as to assess the effect of duration. Linear regression was used to consider the putative relationship between age at onset of dementia and HRT status. HRT use was found to be a statistically significant predictor for Alzheimers disease and vascular dementia. Overall, HRT use did not significantly predict for milder cognitive impairments, although significant interaction effects indicate that HRT may be protective at least for specific sub-groups of women. No durational effect was found for any of the outcomes. Neither did HRT appear to predict for age at onset of dementia. Notably, a large proportion of women in the current study reported using estrogen-only hormone supplements, and therefore generalizations regarding the findings are likely limited to estrogen-only preparations, not combination estrogen-progestin therapies. These findings must be considered within the context of the other known and potential risks and benefits that HRT may afford.

Hormone replacement therapy (HRT) has been studied as a protective factor for cognitive decline and dementia. However, study findings have been inconsistent. Variation in study findings may be due to differences in study designs, small sample size, exposure ascertainment, diagnostic procedures, and inclusion of relevant risk and confounding factors. Moreover, there may be significant differences between the characteristics of women choosing to use HRT and those opting not to use the therapy. Using a large-scale, population-based, cohort study, we examined the relationship between HRT and cognition while paying particular attention to moderating and confounding factors. The main outcomes of interest were to assess differences in risk for cognitive impairments and dementia between HRT user and never user groups; examine HRTs impact on age of onset of dementia; and explore the relationship between duration of HRT and cognitive decline. Logistic regression and Cox Proportional Hazards models were used to test HRT as a predictor for cognitive impairments, Alzheimers disease and vascular dementia, as well as to assess the effect of duration. Linear regression was used to consider the putative relationship between age at onset of dementia and HRT status. HRT use was found to be a statistically significant predictor for Alzheimers disease and vascular dementia. Overall, HRT use did not significantly predict for milder cognitive impairments, although significant interaction effects indicate that HRT may be protective at least for specific sub-groups of women. No durational effect was found for any of the outcomes. Neither did HRT appear to predict for age at onset of dementia. Notably, a large proportion of women in the current study reported using estrogen-only hormone supplements, and therefore generalizations regarding the findings are likely limited to estrogen-only preparations, not combination estrogen-progestin therapies. These findings must be considered within the context of the other known and potential risks and benefits that HRT may afford.

Stroke is the fifth leading cause of death in the United States and a major cause of long-term disability in industrialized countries. The core region of an ischemic stroke dies within minutes due to activation of necrotic pathways. Outside of this core region is the penumbral zone, where some perfusion is maintained via collateral arteries. Delayed cell death occurs in this area due to the triggering of apoptotic mechanisms, which expands the ischemic injury over time. The cellular and molecular events that produce the expansion of the ischemic core continue to be poorly understood. The increases in the amyloid precursor protein and pathogenic secretases lead to the increase in amyloid-β (Aβ) production. The relatively small amount of research in this area has hampered development of stroke therapy designed to prevent neuronal and glial cell degeneration in the penumbra. Currently, there is a significant lack of therapeutic options for acute ischemic stroke, and no drug has been approved for treating patients at delayed time points (≥ 4.5 hr post-stroke). Afobazole, an anxiolytic currently used clinically in Russia, has been shown to reduce neuronal and glial cell injury in vitro following ischemia, both of which have been shown to play important roles following an ischemic stroke. Treatment with afobazole decreased microglial activation in response to ATP and Aβ, as indicated by reduced membrane ruffling and cell migration. Prolonged exposure of microglia to ischemia or Aβ conditions resulted in glial cell death that was associated with increased expression of the pro-apoptotic protein, Bax, the death protease, caspase-3 and a reduced expression in Bcl-2. Co-application of afobazole decreased the number of cells expressing both Bax and caspase-3, while increasing the cells expressing Bcl-2 resulting in a concomitant enhancement in cell survival. While afobazole inhibited activation of microglia cells by Aβ25-35, it preserved normal functional responses in these cells following exposure to the amyloid peptide. Intracellular calcium increases induced by ATP were depressed in microglia after 24 hr exposure to Aβ25-35. However, co-incubation with afobazole returned these responses to near control levels. Therefore, stimulation of sigma-1 and sigma-2 receptors by afobazole prevents Aβ25-35 activation of microglia and inhibits Aβ25-35-associated cytotoxicity. Examining the molecular mechanisms involved in the increased neuronal survival demonstrates that ischemia or Aβ results in an increased expression of the pro-apoptotic protein Bax and the death protease caspase-3, while at the same time decreasing expression of the anti-apoptotic protein, Bcl-2. However, unlike observations made with microglia, afobazole was unable to modulate this ischemia-induced expression, but was able to modulate Aβ-induced expression of apoptotic proteins while still rescuing neurons from death. Additional experiments were carried out to understand this disparity between the failures of afobazole to prevent the up-regulation of pro-apoptotic genes while retaining the ability to mitigate neuronal death. Although the neurons were still alive they were in a senescent state and were unresponsive to depolarization by high K+. However, these findings are still positive due to the ability of afobazole to delay neuron death, thus minimalizing the toxic environment of the penumbra. These comorbidities of ischemia and Aβ toxicity may lead to potentiated responses and increase the risk for various vascular dementias. It was of particular interest to study how the convergence of ischemia, acidosis and Aβ influence cellular activity and survival within core and penumbral regions. Application of Aβ increased the [Ca2+]i overload produced by concurrent ischemia + acidosis application in isolated cortical neurons. We found that the acid-sensing ion channels 1a (ASIC1a) are involved in the potentiation of [Ca2+]i overload induced by Aβ. Furthermore, afobazole (100 uM) abolished Aβ potentiation of ischemia + acidosis evoked [Ca2+]i overload, which may represent a therapeutic strategy for mitigating injury produced by Aβ and stroke.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2005. / Härtill 5 uppsatser.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2006. / Härtill 5 uppsatser.

A hipoperfusão cerebral crônica (HCC) é um importante fator de risco para o declínio cognitivo e outras disfunções cerebrais, tais como Doença de Alzheimer e Demência Vascular. O objetivo deste estudo foi investigar o efeito neuroprotetor do Resveratrol (RSV), avaliando parâmetros comportamentais, bioquímicos e morfológicos, em um modelo experimental de Demência Vascular. Ratos Wistar adultos foram submetidos ao modelo modificado da HCC através da oclusão permanente de 2 vasos (2VO) e tratamento diário, iniciado uma hora após oclusão permanente dos vasos, com injeções intraperitoneais (20 mg/kg) de RSV durante 7 dias. Os testes comportamentais foram realizados entre o 35° e 45° dias após a cirurgia - 2VO, através da tarefa do labirinto aquático de Morris, na qual os animais foram avaliados quanto ao desempenho da memória espacial. Ao final dos testes comportamentais, um grupo dos animais foi perfundido transcardiacamente para análise histológica, outro grupo foi submetido à eutanásia em 3 tempos (3, 14 e 45 dias após a lesão isquêmica) para avaliação da expressão de NGF (fator de crescimento do nervo). Os resultados demonstraram que o tratamento com RSV atenuou significativamente a morte das células piramidais na região CA1 do hipocampo e preveniu o déficit da memória espacial. O aumento da expressão de NGF foi evidenciado no 3° dia após indução da HCC em todos os animais isquêmicos e no 45° dia após indução da HCC nos animais tratados com RSV. Com base nesses dados, hipotetizamos que o aumento, em longo prazo, na expressão de NGF no hipocampo após a HCC pode caracterizar uma das vias envolvidas nos mecanismos neuroprotetores do RSV. / Chronic cerebral hypoperfusion (CCH) is an important risk factor for cognitive decline and other brain dysfunctions, such as Alzheimer’s Disease and Vascular Dementia. The aim of the present study was to investigate the neuroprotective effect of Resveratrol (RSV) on behavioral, biochemical and morphological parameters in an experimental model of Vascular Dementia. Adult Wistar rats were submitted to the CCH modified model by means of permanent 2-vessel occlusion (2VO) and daily treatment, initiated one hour after permanent vessel occlusion, with intraperitoneal injections (20 mg/kg) of RSV for 7 days. Behavioral testing was performed between the 35th and the 45th day after 2VO surgery in the Morris Water Maze task, allowing for the evaluation of spatial memory function. At the end of the behavioral assessment, half of the animals were transcardially perfused for histological analysis and the remaining were euthanized in 3 times (3. 14 and 45 days after ischemic injury) for NGF expression evaluation (neural growth factor). Results demonstrate that the treatment with RSV significantly attenuated pyramidal cell death in CA1 hippocampal field and prevented spatial memory impairment. The increase of NGF expression was evidenced on the 3rd day after CCH induction in all ischemic animals and on the 45th day after CCH induction in animals treated with RSV. On the basis of these data, we hypothesize that the long term increase in NGF expression in the hippocampus after CCH may characterize one pathway involved in the neuroprotective mechanisms of RSV.

A hipoperfusão cerebral crônica (HCC) é um importante fator de risco para o declínio cognitivo e outras disfunções cerebrais, tais como Doença de Alzheimer e Demência Vascular. O objetivo deste estudo foi investigar o efeito neuroprotetor do Resveratrol (RSV), avaliando parâmetros comportamentais, bioquímicos e morfológicos, em um modelo experimental de Demência Vascular. Ratos Wistar adultos foram submetidos ao modelo modificado da HCC através da oclusão permanente de 2 vasos (2VO) e tratamento diário, iniciado uma hora após oclusão permanente dos vasos, com injeções intraperitoneais (20 mg/kg) de RSV durante 7 dias. Os testes comportamentais foram realizados entre o 35° e 45° dias após a cirurgia - 2VO, através da tarefa do labirinto aquático de Morris, na qual os animais foram avaliados quanto ao desempenho da memória espacial. Ao final dos testes comportamentais, um grupo dos animais foi perfundido transcardiacamente para análise histológica, outro grupo foi submetido à eutanásia em 3 tempos (3, 14 e 45 dias após a lesão isquêmica) para avaliação da expressão de NGF (fator de crescimento do nervo). Os resultados demonstraram que o tratamento com RSV atenuou significativamente a morte das células piramidais na região CA1 do hipocampo e preveniu o déficit da memória espacial. O aumento da expressão de NGF foi evidenciado no 3° dia após indução da HCC em todos os animais isquêmicos e no 45° dia após indução da HCC nos animais tratados com RSV. Com base nesses dados, hipotetizamos que o aumento, em longo prazo, na expressão de NGF no hipocampo após a HCC pode caracterizar uma das vias envolvidas nos mecanismos neuroprotetores do RSV. / Chronic cerebral hypoperfusion (CCH) is an important risk factor for cognitive decline and other brain dysfunctions, such as Alzheimer’s Disease and Vascular Dementia. The aim of the present study was to investigate the neuroprotective effect of Resveratrol (RSV) on behavioral, biochemical and morphological parameters in an experimental model of Vascular Dementia. Adult Wistar rats were submitted to the CCH modified model by means of permanent 2-vessel occlusion (2VO) and daily treatment, initiated one hour after permanent vessel occlusion, with intraperitoneal injections (20 mg/kg) of RSV for 7 days. Behavioral testing was performed between the 35th and the 45th day after 2VO surgery in the Morris Water Maze task, allowing for the evaluation of spatial memory function. At the end of the behavioral assessment, half of the animals were transcardially perfused for histological analysis and the remaining were euthanized in 3 times (3. 14 and 45 days after ischemic injury) for NGF expression evaluation (neural growth factor). Results demonstrate that the treatment with RSV significantly attenuated pyramidal cell death in CA1 hippocampal field and prevented spatial memory impairment. The increase of NGF expression was evidenced on the 3rd day after CCH induction in all ischemic animals and on the 45th day after CCH induction in animals treated with RSV. On the basis of these data, we hypothesize that the long term increase in NGF expression in the hippocampus after CCH may characterize one pathway involved in the neuroprotective mechanisms of RSV.

Introdução: Estudos prévios analisaram a associação entre fatores de risco cardiovascular (FRCV) associados ao diagnóstico de demência vascular (DV) provável ou possível. No entanto, não foram encontrados estudos que analisassem a associação entre FRCV e a ocorrência de DV definitiva. Dessa maneira, ainda permanece obscura a associação entre os FRCV e a ocorrência de DV definitiva, ou seja, aquela diagnosticada por meio do exame neuropatológico, no qual se apresenta como padrão ouro. Objetivo: Avaliar a associação entre os FRCV e a ocorrência de DV definitiva, pura e mista. Método: Por meio de um estudo transversal foram analisados 707 casos pertencentes à casuística do Banco de Encéfalos Humanos do Grupo de Estudos em Envelhecimento (BEHGEEC) da FMUSP, que respeitaram os critérios de inclusão. A existência de fatores de risco cardiovascular em vida (Hipertensão Arterial, Diabetes Mellitus, Dislipidemia, Tabagismo, Etilismo, Obesidade e Sedentarismo), reportada por um informante com convivido minimamente semanal durante a autópsia, foi associada ao diagnóstico neuropatológico de demência vascular emitido por um neuropatologista. Modelos de regressão logística (sem e com ajuste para sexo, idade e raça) foram construídos para testar a associação entre os FRCV e o diagnóstico de DV, DV pura e DV mista. Foi testada a capacidade preditiva dos fatores que se mostraram preditores de DV por meio da Curva ROC. Resultados: O sedentarismo foi um preditor independente de DV (OR 1,943; IC95% 1,198 3,151; p= 0,007) e DV pura (OR 3,148; IC95% 1,428 6,941;p= 0,004). A HAS foi um preditor independente de DV mista (OR 2,240; IC95% 1,216 4,126; p= 0.01). O sedentarismo não apresentou boa capacidade preditiva para a DV e DV Pura (AUC = 0,380 e 0,337, respectivamente), assim como a HAS para a DV Mista (AUC = 0,459). Conclusões: Dentre os FRCV o sedentarismo e a HAS foram os que se associaram a um aumento no risco de DV. / Introduction: Previous studies have analyzed the association between cardiovascular risk factors (CVRF) associated with the diagnosis (probable or possible) of vascular dementia (VaD). However, there are no studies that have analyzed the association between CVRF and the occurrence of definitive VaD. The association between CVRF and the occurrence of definite VaD, neuropathologically defined and considered as gold-standard, remains obscure. Objectives: To evaluate the association between CVRF and the occurrence of definitive VaD, pure and mixed. Methods: This is a cross-sectional study which evaluated 707 cases belonging to the Bain Bank of the Brazilian Aging Brain Study Group (BBBABSG) of FMUSP, respecting the inclusion criteria. The history of existence of cardiovascular risk factors in life (hypertension, diabetes mellitus, dyslipidemia, smoking, alcoholism, obesity, and sedentarism) reported by a knowledgeable next-of-kin, with at least weekly contact with the deceased, was associated with the neuropathological diagnosis of vascular dementia reported by a neuropathologist after the autopsy exam. Logistic regression models (with and without adjustment for sex, age and race) were tested to show the association between CVRF and the diagnosis of VaD, pure Vad and mixed VaD. It was also tested the predictive capacity of the factors that proved to be predictors of VaD through the ROC Curve. Results: Sedentary lifestyle was an independent predictor of VaD (OR 1,943, CI 95% 1,198 - 3,151, p = 0.007) and of Pure VaD (OR 3,148, 95% CI, 1.428 - 6.941, p = 0.004). Hypertension was an independent predictor of Mixed VaD (OR 2,240, 95% CI 1,216 - 4,126, p = 0.01). Sedentary lifestyle did not present good predictive capacity for VaD and Pure VaD (AUC = 0.380 and 0.337, respectively), as Hypertension for Mixed DV did not either (AUC = 0.459). Conclusions: Among the CVRF, sedentarism and hypertension were those associated with an increase VaD risk.

A hipoperfusão cerebral crônica (HCC) é um importante fator de risco para o declínio cognitivo e outras disfunções cerebrais, tais como Doença de Alzheimer e Demência Vascular. O objetivo deste estudo foi investigar o efeito neuroprotetor do Resveratrol (RSV), avaliando parâmetros comportamentais, bioquímicos e morfológicos, em um modelo experimental de Demência Vascular. Ratos Wistar adultos foram submetidos ao modelo modificado da HCC através da oclusão permanente de 2 vasos (2VO) e tratamento diário, iniciado uma hora após oclusão permanente dos vasos, com injeções intraperitoneais (20 mg/kg) de RSV durante 7 dias. Os testes comportamentais foram realizados entre o 35° e 45° dias após a cirurgia - 2VO, através da tarefa do labirinto aquático de Morris, na qual os animais foram avaliados quanto ao desempenho da memória espacial. Ao final dos testes comportamentais, um grupo dos animais foi perfundido transcardiacamente para análise histológica, outro grupo foi submetido à eutanásia em 3 tempos (3, 14 e 45 dias após a lesão isquêmica) para avaliação da expressão de NGF (fator de crescimento do nervo). Os resultados demonstraram que o tratamento com RSV atenuou significativamente a morte das células piramidais na região CA1 do hipocampo e preveniu o déficit da memória espacial. O aumento da expressão de NGF foi evidenciado no 3° dia após indução da HCC em todos os animais isquêmicos e no 45° dia após indução da HCC nos animais tratados com RSV. Com base nesses dados, hipotetizamos que o aumento, em longo prazo, na expressão de NGF no hipocampo após a HCC pode caracterizar uma das vias envolvidas nos mecanismos neuroprotetores do RSV. / Chronic cerebral hypoperfusion (CCH) is an important risk factor for cognitive decline and other brain dysfunctions, such as Alzheimer’s Disease and Vascular Dementia. The aim of the present study was to investigate the neuroprotective effect of Resveratrol (RSV) on behavioral, biochemical and morphological parameters in an experimental model of Vascular Dementia. Adult Wistar rats were submitted to the CCH modified model by means of permanent 2-vessel occlusion (2VO) and daily treatment, initiated one hour after permanent vessel occlusion, with intraperitoneal injections (20 mg/kg) of RSV for 7 days. Behavioral testing was performed between the 35th and the 45th day after 2VO surgery in the Morris Water Maze task, allowing for the evaluation of spatial memory function. At the end of the behavioral assessment, half of the animals were transcardially perfused for histological analysis and the remaining were euthanized in 3 times (3. 14 and 45 days after ischemic injury) for NGF expression evaluation (neural growth factor). Results demonstrate that the treatment with RSV significantly attenuated pyramidal cell death in CA1 hippocampal field and prevented spatial memory impairment. The increase of NGF expression was evidenced on the 3rd day after CCH induction in all ischemic animals and on the 45th day after CCH induction in animals treated with RSV. On the basis of these data, we hypothesize that the long term increase in NGF expression in the hippocampus after CCH may characterize one pathway involved in the neuroprotective mechanisms of RSV.