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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Stimulation of central nervous system muscarinic-1 (M1) receptors in animals increases blood pressure, heart rate, and sympathetic outflow. In Alzheimer's disease, stimulation of central M1 receptors is reduced. When the oral formulation of the selective M1 agonist xanomeline was tested for the treatment of Alzheimer's disease, an increased incidence of syncope was observed. Therefore, we used Alzheimer's disease as a model of relative M1 deficiency to determine the effect of M1 receptor stimulation on blood pressure regulation in humans. Eight Alzheimer's patients and 6 healthy age- and sex-matched subjects underwent blood pressure, heart rate, forearm vascular resistance, plasma norepinephrine, and heart rate variability measurements during 90 minutes after ingestion of xanomeline or placebo, then during 45 minutes of head-up tilt. Alzheimer's patients were studied on three occasions: after placebo, the first dose of xanomeline, and 3 days of xanomeline. Normal subjects were studied after placebo and the first dose of xanomeline. A subset of 5 Alzheimer's patients was studied with the peripheral muscarinic antagonist methscopolamine. Oral xanomeline increased supine systolic and diastolic blood pressures in normal subjects and heart rate and plasma norepinephrine in all subjects. During the placebo tilt, 0 of 8 Alzheimer's patients and 2 of 6 healthy subjects developed near-syncope, and during the first-dose xanomeline tilt, 4 of 8 Alzheimer's patients and 3 of 6 healthy subjects had near-syncope. The maximal decrease in systolic blood pressure during tilt was greater with xanomeline than placebo in both groups (P<.03). Methscopolamine did not prevent xanomeline-induced hypotension. Central M1 receptor stimulation with the oral formulation of xanomeline in humans is associated with sympathetic stimulation under supine conditions and impaired baroreflex compensation during tilt. Alzheimer's patients, who presumably lack M1 receptor activity, may have a reduced risk of tilt-induced syncope compared with normal subjects. Both groups, however, have enhanced susceptibility to hypotension and syncope when M1 receptor activity is pharmacologically increased.
Hypertension 1997 Mar
PMID:Effects of central muscarinic-1 receptor stimulation on blood pressure regulation. 905 3

Propionibacterium acnes was found in the cortex of three patients with Alzheimer's disease and in one frontal cortex of an elderly patient with cardiovascular risk factors and hypoxia due to a large glioblastoma of the right frontal lobe with severely increased intracranial pressure. Propionibacterium acnes is an atypical anaerobic bacterium which is sensitive to cephalosporins, but insensitive to metronidazole. It is concluded that a capillary microangiopathy (in consequence of old age and cardiovascular risk factors such as high blood pressure) leads to cortical hypoxia and reduced resistance of the cortical immune system. Prevention by dietary regimes counteracting microangiopathy and treatment with cephalosporins are recommended.
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PMID:Propionibacterium acnes in the cortex of patients with Alzheimer's disease. 883 2

To clarify the neuropathologic criteria for the diagnosis of vascular dementia principally caused by large-vessel cerebral infarction, we solicited autopsy cases of vascular dementia from 10 university neuropathology laboratories. We included only those cases with progressive dementia clinically diagnosed as Alzheimer's disease (AD) or multi-infarct dementia, in whom autopsy revealed only cerebral infarction, without significant neuropathologic features of AD or other neurodegenerative disorders. Only six cases, all men, met these criteria. Each of them had, for a year or longer, gradually increasing cognitive impairment sufficient to interfere with daily activities, without clear evidence of "stepwise" progression. The age of onset of dementia was 66 years or less in five of the six patients. The duration of dementia ranged from 2 to 14 years. Five of the six cases had a history of either cerebral ischemia or acute stroke with residual focal neurologic deficits. Only two were known to have hypertension. At autopsy severe atherosclerosis of the cerebral arteries was present in three cases; two of these had a thrombotic occlusion of one internal carotid artery and one had partial obstruction of other cerebral arteries. In five of six brains, gross infarctions were present involving the thalamus, caudate, putamen, or large portions of the frontal, parietal, and temporal lobes of one or both hemispheres. Vascular amyloid was absent in all but one of these five brains. In four cases, the dementia was clinically indistinguishable from AD except for a history of focal neurologic deficits. The difficulty encountered in finding large numbers of cases of VaD without coexisting neuropathologic evidence of AD suggests that "pure" vascular dementia is very uncommon.
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PMID:Clinical-neuropathologic findings in multi-infarct dementia: a report of six autopsied cases. 940 94

Drug-induced parkinsonism (DIP) is frequent. The list of drugs able to induce parkinsonism is long and probably incomplete, because new drugs, with previously unknown antidopaminergic activity, are constantly being added. Not all the drugs have the same potency for inducing parkinsonism. We classify these drugs in three groups: (1) drugs with obvious antidopaminergic activity which regularly induce parkinsonism; (2) drugs able to induce parkinsonism in particular individuals and (3) drugs which may aggravate Parkinson's disease treated with levodopa. The reports of isolated cases of parkinsonism induced by widely-used drugs (drugs in group 2) may be the result of either an idiosyncratic side effect or a misdiagnosis of parkinsonism. The antidopaminergic activity of the drugs of this group is weak and not sufficiently demonstrated. Maybe, in these cases, the blockage of other neurotransmitters different from dopamine plays a role in the induction of parkinsonism. Probably, the number of patients with DIP is higher than reported or detected, because many patients suffer from weak symptoms that quickly disappear after drug withdrawal. One of the main points of interest is knowing the list, because all these drugs, specially those of group 1, should be avoided or used with caution in the treatment of some common symptomatic problems in patients with Parkinson's disease, such as depression, arterial hypertension, diabetes mellitus and cardiac disorders. The precautions should extent to other populations especially susceptible to suffer from DIP, such as the elderly or patients with other neurodegenerative disorders, such as Alzheimer's disease.
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PMID:Drugs inducing or aggravating parkinsonism: a review. 913 99

High blood pressure is associated with an increased risk of vascular dementia as a result of ischemic stroke and other cerebrovascular events or lesions. However, there is insufficient epidemiologic evidence indicating that blood pressure is involved in the etiology of Alzheimer's disease. Clinical studies suggest that episodes of hypotension may cause cerebral hypoperfusion and play a role in the development of dementia. Lowering of blood pressure in dementia, especially Alzheimer's disease, may be due to the dementia process itself or to the characteristics of the disease. Recent large clinical trials have shown that antihypertensive drugs may not significantly affect cognitive performance, but no data are available regarding their potential effects in decreasing the risk of dementia by lowering the incidence of cerebrovascular events. Some data suggest that the blood pressure-dementia relationship may be age-dependent.
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PMID:Blood pressure and dementia in the elderly: epidemiologic perspectives. 916 70

Mato cells are unique macrophagic cells locating in the Virchow-Robin space of cerebral microvessels. They play a significant role in blood brain barrier, and uptake and digest proteinous and lipoidal materials derived from surroundings. They are provided with epitopes of macrophage lineages such as MHC Class II and scavenger receptor. Under pathological conditions, -cerebral injury, hypercholesteremia, hypertension and congenital dysfunction of nerve and some enzymes-induce heavy damages of Mato cells in shape and contents, and some of Mato cells are going into degeneration. Subsequently, the architecture of microvessels is also modified and result in the narrowing of vascular luminae. Finally, the authors discusses these findings referring to the earlier reports of Alzheimer (1913).
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PMID:[Study on Mato cells (Mato's FGP cells) under various conditions]. 923 38

Ischemic vascular dementia is a clinical syndrome of acquired intellectual impairment with ischemic cerebral injury resulting from occlusion of cerebral blood vessels and loss of cerebral tissue caused by cerebrovascular disease. With increasing life expectancy, the developed countries have experienced a shift towards a progressively older population. As the average age of the population increases, the prevalence of cerebrovascular disease and vascular dementia is likely to increase. The risk of vascular dementia seems to be correlated with the epidemiologic risk factors of stroke, namely hypertension. Hypertension is thought to be directly associated with vascular dementia and preliminary evidence suggests an association between elevated blood pressure and impairments in cognitive functioning. Recent investigations have found significant associations between hypertension and cerebral dilation and left hemisphere atrophy, and an increased incidence of white matter hyperintensities among hypertensives. Treatment and prevention of vascular dementia and cognitive dysfunction in the elderly require attention to cerebrovascular risk factors, particularly hypertension. Vascular dementias are potentially preventable and cases of Alzheimer's disease with vascular components are becoming increasingly recognized.
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PMID:Vascular dementia, hypertension, and the brain. 932 23

A possible relation between cerebral white-matter injury and dementia was intuitively attributed by Alzheimer to changes affecting the small penetrating vessels that supply the cerebral white matter. Several observations support the view that white-matter changes detectable by neuroimaging may contribute to cognitive deficits in the elderly. But many questions concerning this matter remain partially answered. In this communication we review: (1) Selected anatomic features of the blood vessels supplying the white matter; (2) possible pathogenetic mechanisms responsible for the white-matter changes; (3) observations on humans and animals suggesting a causal relationship between ischemia/hypoxemia and white-matter injury; (4) epidemiologic studies linking white-matter abnormalities with cognitive disorders. We conclude that abnormalities in the small vessels caused by aging and arterial hypertension, or other processes (cerebral amyloid angiopathy, CADASIL) together with systemic circulatory disturbances, such as abrupt variations in blood pressure values or cardiac diseases, may be the substrate of selective white-matter injury. The damage is structurally characterized by incomplete infarction or selective cellular injury.
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PMID:Cognitive impairment and cellular/vascular changes in the cerebral white matter. 932 83

Our objectives were to investigate the utility of the Hachinski Ischemic Score (HIS) in differentiating patients with pathologically verified Alzheimer's disease (AD), multi-infarct dementia (MID), and "mixed" (AD plus cerebrovascular disease) dementia, and to identify the specific items of the HIS that best discriminate those dementia subtypes. Investigators from six sites participated in a meta-analysis by contributing original clinical data, HIS, and pathologic diagnoses on 312 patients with dementia (AD, 191; MID, 80; and mixed, 41). Sensitivity and specificity of the HIS were calculated based on varied cutoffs using receiver-operator characteristic curves. Logistic regression analyses were performed to compare each pair of diagnostic groups to obtain the odds ratio (OR) for each HIS item. The mean HIS (+/- SD) was 5.4 +/- 4.5 and differed significantly among the groups (AD, 3.1 +/- 2.5; MID, 10.5 +/- 4.1; mixed, 7.7 +/- 4.3). Receiver-operator characteristic curves showed that the best cutoff was < or = 4 for AD and > or = 7 for MID, as originally proposed, with a sensitivity of 89.0% and a specificity of 89.3%. For the comparison of MID versus mixed the sensitivity was 93.1% and the specificity was 17.2%, whereas for AD versus mixed the sensitivity was 83.8% and the specificity was 29.4%. HIS items distinguishing MID from AD were stepwise deterioration (OR, 6.06), fluctuating course (OR, 7.60), hypertension (OR, 4.30), history of stroke (OR, 4.30), and focal neurologic symptoms (OR, 4.40). Only stepwise deterioration (OR, 3.97) and emotional incontinence (OR, 3.39) distinguished MID from mixed, and only fluctuating course (OR, 0.20) and history of stroke (OR, 0.08) distinguished AD from mixed. Our findings suggest that the HIS performed well in the differentiation between AD and MID, the purpose for which it was originally designed, but that the clinical diagnosis of mixed dementia remains difficult. Further prospective studies of the HIS should include additional clinical and neuroimaging variables to permit objective refinement of the scale and improve its ability to identify patients with mixed dementia.
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PMID:Meta-analysis of the Hachinski Ischemic Score in pathologically verified dementias. 933 96

White matter changes in Alzheimer's disease patients were the subject of the study. One hundred and seventeen cases clinically diagnosed according to NINCDS-ADRDA criteria as probable Alzheimer's disease were assessed. In computer tomography two types of pathological changes were observed; the so called leucoaraiosis and the perivascular focal alterations. Leucoaraiosis appeared in 20% of cases and focal changes were visible only in 4 cases A significant correlation was found between the presence of leucoaraiosis and the age and the presence of coronary disease. Hypertension, diabetes and brain atrophy did not seem to influence the occurrence of white matter alterations of either type.
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PMID:[The significance of cerebral white matter changes in CT images in Alzheimer's disease]. 938 Feb 54


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