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 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A wide variety of anatomic and histological alterations are common in brains of aged individuals. However, identification of intrinsic aging changes--as distinct from changes resulting from cumulative environmental insult--is problematic. Some degree of neuronal and volume loss would appear to be inevitable, but recent studies have suggested that the magnitudes of such changes are much less than previously thought, and studies of dendritic complexity in cognitively intact individuals suggest continuing neuronal plasticity into the eighth decade. A number of vascular changes become more frequent with age, many attributable to systemic conditions such as hypertension and atherosclerosis. Age-associated vascular changes not clearly linked to such conditions include hyaline arteriosclerotic changes with formation of arterial tortuosities in small intracranial vessels and the radiographic changes in deep cerebral white matter known as "leukoaraiosis." Aging is accompanied by increases in glial cell activation, in oxidative damage to proteins and lipids, in irreversible protein glycation, and in damage to DNA, and such changes may underlie in part the age-associated increasing incidence of "degenerative" conditions such as Alzheimer disease and Parkinson disease. A small number of histological changes appear to be universal in aged human brains. These include increasing numbers of corpora amylacea within astrocytic processes near blood-brain or cerebrospinal fluid-brain interfaces, accumulation of the "aging" pigment lipofuscin in all brain regions, and appearance of Alzheimer-type neurofibrillary tangles (but not necessarily amyloid plaques) in mesial temporal structures.
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PMID:Aging-associated changes in human brain. 941 75

Hypertension has been related to the development of dementia, including Alzheimer's disease, and cognitive dysfunction in middle-aged and elderly populations. One possible explanation is that hypertension is a risk factor for cerebral infarcts and ischaemic subcortical white-matter lesions. Hypertension may also give rise to a blood-brain barrier dysfunction, which has been suggested to be involved in the aetiology and pathogenesis of Alzheimer's disease. Other possible explanations for the association are shared risk factors, such as psychological stress, and the formation of free oxygen radicals. Low blood pressure has also been hypothesized to give rise to brain damage and dementia. However, the brain is involved in blood pressure regulation and dementia disorders may therefore influence the blood pressure. The findings of an association between hypertension and dementia may have implications for prevention and treatment.
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PMID:The relationship between blood pressure and dementia: a review. 945 85

The aetiology of the common dementias of old age remains incompletely understood. Here we describe some of the biological, neurophysiological and psychological changes associated with ageing of the human brain, in terms of those that occur throughout life and those that are characteristic of senescence. Age-dependent diseases, such as Alzheimer's disease (AD), idiopathic Parkinson's disease (IPD) and dementia with Lewy bodies (DLB), are considered from these viewpoints, and risk factors described. Vascular dementia (VaD) is related to hypertension and atherosclerosis and detailed description of its pathogenesis is outside the scope of this review. The importance of age as the main risk factor raises basic questions about the relationship of these diseases to the ageing process itself. Similarities and differences between ageing and disease may be important for a rational approach to prevention and treatment of cognitive decline and dementia in later life.
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PMID:Some developments in brain ageing and dementia. 949 98

This article examines the association between ethnicity and psychiatric symptoms in patients with Alzheimer's disease. Data from a cross-sectional study of patients evaluated at nine California Department of Health Alzheimer's Disease Diagnostic and Treatment Centers (ADDTCs) were used. Using the ADDTC patient database, sociodemographic and clinical variables in 207 black patients and 1818 white patients with probable and possible Alzheimer's disease were compared. Logistic and linear regression analysis indicated the following results: 1) black patients had fewer years of education and more often had hypertension, 2) black patients reported shorter duration of illness at the time of initial diagnosis of dementia, 3) black patients had lower Mini-Mental State Examination scores and higher Blessed Roth Dementia Rating Scale scores at the time of initial diagnosis, and 4) black patients more frequently reported insomnia and less frequently reported anxiety. Additional studies are needed to validate these findings and to generate hypotheses about the role of cardiovascular disease and pathophysiology of psychiatric symptoms in ethnic populations with Alzheimer's disease.
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PMID:Clinical aspects of Alzheimer's disease in black and white patients. 951 Jun 21

Many efforts have been made to trace the causes of Alzheimer's disease (AD). There are, however, many points of controversy among reports from the same country as well as among reports from different countries. The current study is a case-control study to determine the risk factors in the development of AD in Greece. Sixty-five patients with AD and 69 age-matched controls were examined. All patients with AD fulfilled the DSM-IV criteria for AD and NINCDS-ADRDA criteria for probable AD. Demographic characteristics such as gender, current marital status, who he/she is living with, education, main place of residence in childhood, adulthood, and late life, occupational hazards, patient's medical history (history of diabetes mellitus and hypertension), life habits like alcohol consumption and smoking, and a history of head trauma, heart attack, stroke, parkinsonism, or depression were collected from the subject or from an informant. A family history of selected diseases (hypertension, diabetes mellitus, dementia, Parkinson's disease, Down's syndrome, stroke) was also elicited. Ages of father and mother at birth were also recorded. Chi-square test, Kruskal-Wallis analysis of variance, cluster analysis, and logistic regression analysis were used for statistical analysis. The results (chi-square test) showed a statistically significant difference between patients with dementia of the Alzheimer type and controls as far as marital status (p = .04), the subject's history of major depressive episode (p = .02), and family history of dementia (p = .002) were concerned. Logistic regression analysis results produced a complex model of family aggregation of dementia, with patients with a history of depression and family history of dementia having an up to seven times higher risk of developing AD. These findings, especially a family history of dementia, are consistent with most of the literature.
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PMID:Risk factors for clinically diagnosed Alzheimer's disease: a case-control study of a Greek population. 951 31

It is concluded that the most important determinants for cerebral neurodegenerative changes and cognitive decline during aging are neuronal shrinkage and/or loss, which are accelerated by certain risk factors: e.g. TIAs, hypertension, heart disease, hyperlipidemia, smoking, heavy alcohol consumption, male gender, low educational status, family history of cerebrovascular disease and absence of estrogen replacement therapy among women. Some of these risk factors are remediable by therapeutic interventions, including prevention of TIAs and medications that control hypertension, heart disease, hyperlipidemia and estrogen replacement in postmenopausal women, as well as abstention from abuse of tobacco and alcohol. Cerebral neurodegenerative changes measured by neuroimaging appear to be premorbid markers for depleted neuronal and synaptic reserves which predispose to the onset of dementias of both VAD and DAT types. Normal subjects at risk for cognitive decline include those with TIAs, hypertension and heart disease since these risk factors measurably accelerate cerebral atrophy, ventricular enlargement, leukoaraiosis, and decline in cortical perfusion.
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PMID:Risk factors for cerebral degenerative changes and dementia. 951 69

The two most common causes of vascular dementia (VAD) are dementia evolving in connection with multiple small or large strokes and dementia related to ischemic white-matter lesions (WMLs) of the brain. The knowledge about risk factors for these disorders is still scarce. Besides sharing risk factors with stroke, dementia with multiple small or large brain infarcts is also associated with non-vascular risk factors such as high alcohol consumption, psychological stress in early life, lower formal education, blue collar occupation, and occupational exposures. Risk factors for dementia in stroke victims include stroke-related and non-stroke related risk factors. Non-stroke-related factors are similar to those found in Alzheimer's disease. The main risk factors for ischemic WMLs are hypertension or increased blood pressure, but WMLs have also been associated with a number of other vascular risk factors. In recent years, Alzheimer's disease (AD) has also been reported to be associated with vascular risk factors, including hypertension, coronary heart disease, atrial fibrillation, diabetes mellitus, and WMLs. Although these associations may reflect an overdiagnosis of AD in cases with silent cerebrovascular disease, or that cerebrovascular disease increases the possibility that individuals with Alzheimer lesions will express a dementia syndrome, there are also alternative explanations. AD and cerebrovascular disease may for instance share similar risk factors or etiologic pathways. The pathogenetic implications for the association between AD and vascular factors need to be further explored. There is also a need for more studies on risk factors for VAD and risk factors for dementia in stroke samples, as well as studies on non-vascular risk factors for ischemic WMLs.
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PMID:Status of risk factors for vascular dementia. 954 18

Intracranial vasculitis, or primary angiitis of the central nervous system (PACNS), is an uncommon, often fatal disorder that frequently responds to aggressive immunosuppressive therapy. Magnetic resonance imaging (MRI), cerebral angiography, and brain biopsy are diagnostic modalities that vary in invasiveness and diagnostic accuracy. The purpose of this study was to determine whether certain clinical or radiologic features were predictive of a diagnostic biopsy. Thirty consecutive patients undergoing brain biopsy to "rule out vasculitis" were studied. Nine patients demonstrated granulomatous or lymphocytic vasculitis, 1 had lymphocytic vasculitis and encephalitis secondary to arbovirus infection, 5 had thickened vessels consistent with hypertensive changes, 5 had amyloid angiopathy and/or changes of Alzheimer disease, 5 demonstrated no pathologic abnormalities, and 1 each had acute infarct, vascular malformation, aneurysm, acellular fibrinoid necrosis, and demyelination. The spectrum of MRI and angiographic changes associated with PACNS were nonspecific, overlapping extensively with changes of chronic hypertension and amyloid deposition. The predictive values of brain biopsy (90-100%) were significantly higher than those of angiography (37-50%) or MRI (43-72%). In this study, morbidity associated with aggressive immunosuppression was significantly greater than that associated with cerebral angiography or brain biopsy. Thus, wedge biopsy of cortical and leptomeningeal tissues is central to the multi-disciplinary approach to a patient with clinical suspicion of PACNS.
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PMID:Diagnosis of intracranial vasculitis: a multi-disciplinary approach. 960 Jan 95

The goals of this study were twofold: to determine whether species differences in Abeta N-terminal heterogeneity explain the absence of neuritic plaques in the aged dog and aged bear in contrast to the human; and to compare Abeta N-terminal isoforms in parenchymal vs cerebrovascular Abeta (CVA) deposits in each of the species, and in individuals with Alzheimer disease (AD) vs nondemented individuals. N-terminal heterogeneity can affect the aggregation, toxicity, and stability of Abeta. The human, polar bear, and dog brain share an identical Abeta amino acid sequence. Tissues were immunostained using affinity-purified polyclonal antibodies specific for the L-aspartate residue of Abeta at position one (AbetaN1[D]), D-aspartate at N1 (AbetaN1[rD]), and pyroglutamate at N3 (AbetaN3[pE]) and p3, a peptide beginning with leucine at N17 (AbetaN17[L]). The results demonstrate that each Abeta N-terminal isoform can be present in diffuse plaques and CVA deposits in AD brain, nondemented human, and the examined aged animal models. Though each Abeta N-terminal isoform was present in diffuse plaques, the average amyloid burden of each isoform was highest in AD vs polar bear and dog (beagle) brain. Moreover, the ratio of AbetaN3(pE) (an isoform that is resistant to degradation by most aminopeptidases) vs AbetaN17(L)-x (the potentially nonamyloidogenic p3 fragment) was greatest in the human brain when compared with aged dog or polar bear. Neuritic plaques in AD brain typically immunostained with antibodies against AbetaN1(D) and AbetaN3(pE), but not AbetaN17(L) or AbetaN1(rD). Neuritic deposits in nondemented individuals with atherosclerotic and vascular hypertensive changes could be identified with AbetaN1(D), AbetaN3(pE), and AbetaN1(rD). The presence of AbetaN1(rD) in neuritic plaques in nondemented individuals with atherosclerosis or hypertension, but not in AD, suggests a different evolution of the plaques in the two conditions. AbetaN1(rD) was usually absent in human CVA, except in AD cases with atherosclerotic and vascular hypertensive changes. Together, the results demonstrate that diffuse plaques, neuritic plaques, and CVA deposits are each associated with distinct profiles of Abeta N-terminal isoforms.
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PMID:N-terminal heterogeneity of parenchymal and cerebrovascular Abeta deposits. 960 Jan 99

Talsaclidine, a novel M1-receptor selective muscarinic agonist for cholinergic substitution therapy of Alzheimer's disease, activates the sympathetic nervous system in guinea pigs and dogs at the orthosympathic ganglia and the paraganglionic adrenals. Results from guinea pigs provide indirect evidence for an additional central site of action. The present investigation in anaesthetized and vagotomized guinea pigs intended to demonstrate central activation of the sympathetic nervous system directly by comparing the blood pressure effects of intracerebroventricular and intravenous injections of small doses of talsaclidine. Increasing doses of 0.2 and 0.6 mg/kg talsaclidine were injected alternately into the third cerebral ventricle and intravenously in 6 guinea pigs before and after blockade of peripheral muscarinic receptors with 1 mg/kg ipratropium bromide i.v. In another group of 6 animals the injections were given into the cisterna cerebellomedullaris using the same protocol. In both groups central administration of talsaclidine caused dose-related hypertension while intravenous injections were hypotensive. Ipratropium bromide, a peripheral antimuscarinic drug, reversed this hypotensive action of intravenous talsaclidine into hypertension, but did not inhibit the effects of central administration. In contrast, atropine, an antimuscarinic drug which passes the blood-brain barrier, abolished the effect of 0.6 mg/kg talsaclidine injected into the cisterna cerebellomedullaris of 8 guinea pigs. The hypertensive effect of a first injection of 0.6 mg/kg talsaclidine into the cisterna cerebellomedullaris of 6 guinea pigs was approximately twice as large as that of a second given 90 min after bilateral adrenalectomy. Sham operation in another 6 animals was not inhibitory. The results demonstrate that talsaclidine, a selective muscarinic M1-receptor agonist, activates central parts of the sympathetic nervous system, including central projections of the adrenals by an action mediated by central muscarinic receptors.
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PMID:Central activation of the sympathetic nervous system including the adrenals in anaesthetized guinea pigs by the muscarinic agonist talsaclidine. 960 29


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