Biomedical subjects

K F Mortel

Publications and source records attributed to K F Mortel.

At least 37 records · Page 2Linked to original sources

PubMed1990

Diabetes mellitus as a risk factor for stroke.

To evaluate the relative potency of diabetes mellitus as a risk factor for stroke, the relative frequency of stroke symptoms was compared among cohorts with and without diabetes. Stroke symptoms were classified as atherothrombotic cerebral infarctions, transient ischemic attacks, reversible ischemic neurologic deficits, and multi-infarct dementia. The groups were compared according to the occurrence of these symptoms, and both cross-sectional and longitudinal designs were used to study 293 consecutive patients referred to this laboratory and to contrast groups with and without diabetes. Hypertension, heart disease, and stroke symptoms and signs were more frequent among diabetics than among age-matched nondiabetics. Among diabetics, strokes occurred at an earlier age and were more common among men. Regression analyses assigned diabetes second to hypertension as a risk factor for stroke, followed by heart disease and smoking. Diabetes associated with hypertension or hyperlipidemia added significantly to stroke risk. Initially, cerebral blood flow values and cognitive test scores were equivalent among diabetics and nondiabetics; after 3 years, cognition became significantly impaired among diabetics, despite better maintenance of cerebral blood flow among treated diabetics compared with nondiabetics. Diabetes acts to compound risk for stroke not only by promoting cerebral atherogenesis but also by aggravating other risk factors including hypertension, heart disease, and hyperlipidemia.

Age Factors↗

PubMed1990

After reaching retirement age physical activity sustains cerebral perfusion and cognition.

Among neurologically normal volunteers approaching age 65 with an option for retirement, a four-year prospective longitudinal study was designed to examine effects of different levels of physical activity on cerebral perfusion by between-group comparisons. After the fourth year, cognitive performance was also tested. Three groups were compared, each composed of 30 elderly volunteers, assigned as follows: Group 1, who continued to work; Group 2, who retired but participated in regular physical activities; and Group 3, who retired but did not participate in regular, planned physical activities. Retirees who elected to become physically inactive exhibited significant declines in cerebral blood flow (CBF) throughout four years of follow-up. Those who continued to work or retirees who elected to participate in regular activities sustained more constant CBF levels. Active retirees and those who continued to work also scored better on cognitive testing after the fourth year of follow-up compared to inactive retirees.

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PubMed1989

Randomized clinical trial of daily aspirin therapy in multi-infarct dementia. A pilot study.

Seventy multi-infarct dementia patients were randomized into an aspirin-treated group and an untreated control group for an exploratory investigation to determine any effects of 325 mg aspirin daily on cognitive performance. The control group did not receive placebo but evaluations were carried out in a blinded manner. The index group (N = 37, mean age 67.1 years) received 325 mg of aspirin by mouth once daily while the control group (N = 33, mean age 67.6 years) was followed and treated in a similar manner except that they received no aspirin. Both groups had comparable risk factors for stroke, which were treated similarly, as well as comparable initial cerebral blood flow values, as measured by the 133xenon inhalation method, and initial scores on Cognitive Capacity Screening Examination testing. Patients were evaluated at intervals of one year. Significant improvements were demonstrated for cerebral perfusion values (P less than .0001) and cognitive performance scores (P less than .0001) among aspirin-treated patients compared to untreated controls at each of three annual follow-up evaluations. Both men and women benefited from aspirin therapy and their quality of life and independence appeared to be improved, which was not apparent in the control group. Daily aspirin appears to improve or stabilize declines in cerebral perfusion and cognition among patients with multi-infarct dementia.

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PubMed1989

Reducing hypertriglyceridemia in elderly patients with cerebrovascular disease stabilizes or improves cognition and cerebral perfusion.

Effects of lowering serum triglyceride levels were investigated among 44 elderly hypertriglyceridemic patients with risk factors for stroke, reduced cerebral perfusion, and a history compatible with symptomatic occlusive cerebrovascular disease. Patients were randomly assigned to either treatment with gemfibrozil, a lipid-lowering agent, or control conditions. Subjects in both groups were instructed to follow a diet recommended for lowering serum lipid levels, while the treatment group was additionally administered 600 mg daily of gemfibrozil. Subjects assigned to the treatment group (n = 22) showed significant reductions in serum triglyceride levels (p less than .0005). Control subjects (n = 22) did not show any significant changes in serum triglyceride levels. There were also no significant changes in total cholesterol levels in either group. Analyses of values for mean bihemispheric gray matter cerebral blood flow measured by the xenon 133 inhalation method and cognitive scores tested by the Cognitive Capacity Screening Examination indicated that gemfibrozil-treated patients maintained significantly higher levels of cerebral perfusion and cognitive performance than untreated controls did. Regression analyses for different treatment intervals indicated that both cerebral blood flow and cognition showed linear improvements that correlated directly with the duration of treatment. Lowering triglyceride levels in hyperlipidemic subjects appears to benefit cerebral perfusion and cognitive performance after four to six months.

Cerebrovascular Circulation↗

PubMed1988

Aetiological considerations and risk factors for multi-infarct dementia.

One hundred and seventy five multi-infarct dementia (MID) patients were evaluated for risk factors for stroke as well as for the types of cerebrovascular lesions that were present. The incidence of associated risk factors for stroke were as follows: hypertension (66%), heart disease (47%), cigarette smoking (37%), diabetes mellitus (20%), moderate alcohol consumption (19%) and hyperlipidaemia (21%). The most frequently occurring type of lesions were multiple lacunar infarctions of the brain (43%). These were combined with other types of stroke in an additional 21%. Atherosclerotic occlusive disease of the carotid and vertebrobasilar arteries occurred alone in 18% and was associated with other types of stroke in another 25%. Embolic cerebral infarctions were present alone in 8% and were combined with other types of stroke in 15%. MID was more frequent in men (62%) than women (p less than 0.002). Mean bihemispheric gray matter cerebral blood flow (CBF) values showed a fluctuating course and when results were pooled and compared between different types of MID, extracranial occlusive disease and/or multiple lacunar infarctions resulted in lowest CBF values. The location of cerebral infarctions was more importantly related to cognitive impairments than was the total volume of infarcted brain. Mortality rates among 125 MID patients followed for 31 months has been 5%. Correct clinical classification of the types of cerebrovascular lesions was confirmed in three necropsied cases.

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PubMed1988

Cognition and cerebral blood flow fluctuate together in multi-infarct dementia.

Longitudinal measurements of cognitive ability measured by serial testing using the Cognitive Capacity Screening Examination (CCSE) were correlated with cerebral blood flow (CBF) throughout (mean +/- SD) 19.9 +/- 12.6 months among 57 patients with multi-infarct dementia, 17 with dementia of the Alzheimer's type, 10 with both, and among 32 age-matched elderly normal controls. Longitudinal CCSE and CBF measurements among controls yielded stable normative values. Reduced mean CCSE scores correlated directly with CBF reductions in patients with multi-infarct dementia (p less than 0.0005) and dementia of the Alzheimer's type (p less than 0.028). Patients with multi-infarct dementia had CCSE scores with retest variability exceeding those of controls (p less than 0.001) and of patients with dementia of the Alzheimer's type (p less than 0.003). CCSE scores and CBF changed together 78.6% (p less than 0.001) of the time in patients with multi-infarct dementia compared with 66.2% of the time (p less than 0.01) in those with both, 62.9% of the time (p less than 0.05) in those with dementia of the Alzheimer's type, and 47.7% of the time (NS) in controls. Further analyses indicated that changes in CCSE scores and CBF were predominantly progressive declines in patients with dementia of the Alzheimer's type, whereas the changes were more bidirectional (both increases and decreases) in patients with multi-infarct dementia; these differences were also significant. Results support the diagnostic usefulness of the Hachinski ischemic scale and confirm that both cognition and CBF fluctuate together among patients with multi-infarct dementia, whereas patients with dementia of the Alzheimer's type exhibit a more stable course, with progressive declines in cognition and CBF.

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PubMed1987

Hyperlipidemia is a risk factor for decreased cerebral perfusion and stroke.

Possible effects of chronically elevated serum cholesterol and triglyceride levels on measurements of cerebral blood flow were investigated by between-group comparisons of individuals, with and without hyperlipidemia, among 56 neurologically normal elderly volunteers and among 102 age-matched patients with symptoms of transient ischemic attacks (TIAs). Results demonstrated significantly higher levels of serum cholesterol and triglyceride among the TIA patients compared with randomly selected age-matched normal controls of similar educational and environmental backgrounds. Cerebral blood flow levels were reduced among groups of TIA patients with elevated levels of either cholesterol or triglycerides compared with the TIA patients with normal lipid levels. Similar trends were seen among normal volunteers, but these did not reach levels of statistical significance because of the limited numbers available. Analysis of frequency distributions for risk factors other than hyperlipidemia indicated that hypertension, atherosclerotic heart disease, diabetes mellitus, and cigarette smoking were also more prevalent among TIA patients than among age-matched normal controls.

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PubMed1986

Cognitive performance correlates with cerebrovascular impairments in multi-infarct dementia.

Cerebral blood flow (CBF) was measured by the 133Xe inhalation method in patients with multi-infarct dementia (MID, N = 26), Alzheimer's dementia (AD, N = 19), and among age-matched, neurologically normal, healthy volunteers (N = 26). Cognitive performance was assessed in all subjects using the Cognitive Capacity Screening Examination (CCSE). Cerebral vasomotor responses were calculated from differences in values of mean hemispheric gray matter blood flow (Delta CBF) measured during inhalation of 100% oxygen (hyperoxia) compared with CBF measured while breathing room air. Significant correlations were found between CCSE performance and vasomotor responsiveness in patients with MID (P less than .01), but not in patients with AD or in neurologically normal volunteers. Loss of vasomotor responsiveness is an indicator of cerebrovascular disease with rigidity and/or loss of reactivity of cerebral vessels, which impairs cerebrovascular responses to situational demands and predisposes to cerebral ischemia. Loss of cerebral vasomotor responsiveness among MID patients, which is a biologic marker of cerebrovascular disease, provides confirmatory evidence of the vascular etiology of MID and assists in separating MID from AD patients.

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PubMed1986

Decreased cerebral blood flow precedes multi-infarct dementia, but follows senile dementia of Alzheimer type.

A 7-year prospective study among 181 neurologically normal elderly volunteers (mean age, 70.6 years) revealed an incidence of 3.3%, or 0.47% new cases per year, for Alzheimer's disease (SDAT) and 5.5%, or 0.78% new cases per year, for multi-infarct dementia (MID). The unusually high incidence of MID is considered to reflect preselection of a large percentage of volunteers (48.6%) with risk factors for (but without symptoms of) atherothrombotic stroke. Of 88 volunteers at risk of stroke, 11.4% developed MID within 7 years. In MID patients, cerebral blood flow (CBF) values began to decline around 2 years before onset of symptoms, while in SDAT patients, CBF levels remained normal until symptoms of dementia appeared; thereafter, CBF declined rapidly.

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PubMed1985

Cerebral blood flow and cognitive testing correlate in Huntington's disease.

Brain atrophy estimated by computed tomographic (CT) scanning and mean hemispheric and regional gray matter cerebral blood flow (CBF) values were measured in patients with mild to moderate Huntington's disease (HD) (N = 16) using the xenon Xe 133 inhalation method and in asymptomatic blood relatives at risk from HD (N = 6) using both the xenon Xe 133 inhalation and the stable xenon CT contrast CBF methods. Results were compared with measurements in two groups of age-matched normal volunteers (N = 48 and N = 42, respectively). Significant brain atrophy in the vicinity of both caudate nuclei was present in patients with HD but not in at-risk individuals. Mean hemispheric xenon Xe 133 CBF values were reduced in patients with HD but seemed to be normal in at-risk individuals. In HD, reductions in CBF were found in both frontotemporal regions. Correlations were found between severity of dementia estimated by reductions of Mini-Mental Status Questionnaire scores and reductions of either mean hemispheric or regional frontotemporal CBF values in HD. The CT estimates of brain atrophy and three-dimensional CBF by stable xenon-contrast measurements were normal in asymptomatic individuals at risk from HD.

Adult↗

PubMed1985

Age-related reductions in cerebral vasomotor reactivity and the law of initial value: a 4-year prospective longitudinal study.

A group of 51 neurologically normal, middle-aged and elderly volunteers (aged 35-86 years; mean age 63.24 years) with and without risk factors for stroke were given annual tests of cerebral vasomotor reactivity to assess any changes in the cerebral vascular capacitance associated with advancing age that might alter cerebral vasomotor reactivity. Cerebral vasomotor reactivity was estimated as the difference in bihemisphere gray matter CBF measured by the 133Xe inhalation method in the steady state breathing room air, followed by a second measurement during inhalation of 100% oxygen. There were significant and progressive reductions in cerebral vasomotor reactivity during the 4-year longitudinal study. Positive linear correlations were apparent between initial steady-state mean bihemisphere gray matter CBF levels and degrees of vasomotor reactivity, suggesting that the Law of Initial Value plays an important role. This should be borne in mind when analyzing scores of cerebral vasomotor reactivity. In the present communication, analysis of covariance was used to correct for influences of initial CBF levels on vasomotor responses tested while breathing pure oxygen.

Aged↗

PubMed1985

Cerebral atrophy and hypoperfusion improve during treatment of Wernicke-Korsakoff syndrome.

Nineteen patients with sudden onset of impaired recent memory, cerebellar ataxia, peripheral neuropathy, and other signs of Wernicke-Korsakoff syndrome (WKS) were treated and examined prospectively for 3 months. Serial studies included histories, neurological examinations, cognitive capacity screening examinations (CCSE), computed tomography (CT) scans, and measurements of regional CBF. Patients were detoxified and withdrawn from sedatives before CBF measurements were examined. Treatment included alcohol withdrawal, nutritious diet, and 300 mg thiamine daily. Before treatment CCSE scores and blood flow values of both white and gray matter were reduced, particularly within both temporoparietal regions. After treatment of compliant patients (n = 10), white and gray matter blood flow increased concurrently with improved CCSE scores. Abnormal eye signs, ataxia, peripheral neuropathy, and performance of activities of daily living also improved. Cerebral atrophy and ventricular enlargement measured by CT decreased. Early recognition and treatment of WKS in compliant patients permit rapid reversals of cognitive and neurological impairments associated with increased blood flow of gray and white matter and improvements of brain atrophy measured by CT scanning.

Adult↗

PubMed1984

Progressive cerebral ischemia antedates cerebrovascular symptoms by two years.

Prospective longitudinal cerebral blood flow values were serially plotted over a four-year interval against the course of cerebral ischemia before, during, and after onset of clinical symptoms. Of 161 normal subjects (mean age, 62 years), 86 were risk free and 75 had hypertension, heart disease, diabetes mellitus, and/or hyperlipidemia. Twenty-one subjects developed cerebrovascular symptoms during the prospective trial. Mean hemispheric cerebral blood flow values were significantly lower for at risk than for risk-free subjects. Symptomatic subjects showed lower values than those in either of the two asymptomatic groups at every session. Statistical analysis of cerebral blood flow values for symptomatic patients compared one and two years prior to onset of symptoms, at the onset of symptoms, and 1 year later showed reductions compared to asymptomatic risk-factored subjects tested in a similar prospective manner. Measurable declines in cerebral perfusion accompany development and progression of aortocerebral atherosclerosis prior to clinical appearance of signs and symptoms of cerebrovascular disease. If confirmed, these observations should permit the institution of preventive medical and/or surgical interventive measures and an evaluation of their outcome.

Adult↗

PubMed1984

Normal pressure hydrocephalus. Influences on cerebral hemodynamic and cerebrospinal fluid pressure--chemical autoregulation.

Blood flow in the cerebral gray matter was measured in normal pressure hydrocephalus and Alzheimer disease by 133Xe inhalation. Flow values in the frontal and temporal gray matter increased after lowering cerebrospinal fluid (CSF) pressure by lumbar puncture in normal pressure hydrocephalus (p less than 0.05) and also after shunting. One case with cerebral complications did not improve clinically. In Alzheimer disease the reverse (decreases in flow in the gray matter) occurred after removal of CSF. Normal pressure hydrocephalus was associated with impaired cerebral vasomotor responsiveness during 100% oxygen and 5% carbon dioxide inhalation. This complication was restored toward normal after CSF removal and/or shunting. Cerebral blood flow measurements appear to be useful for confirming the diagnosis of normal pressure hydrocephalus and predicting the clinical benefit from shunting.

Adult↗

PubMed1984

The effects of chronic cigarette smoking on cerebrovascular responsiveness to 5 per cent CO2 and 100 per cent O2 inhalation.

Effects of chronic cigarette smoking on cerebrovascular responsiveness of volunteers at risk for stroke and not at risk for stroke were evaluated by serial measurements of cerebral blood flow using the 133Xe inhalation method. Resting gray matter blood flow values (Fg) measured while breathing room air were compared with Fg values measured during inhalation of either 5 per cent CO2 in air or 100 per cent O2. Changes in Fg values during inhalation of 5 per cent CO2 were used to estimate cerebral vasodilator capacitance, and those during inhalation of 100 per cent O2 were used to estimate cerebral vasoconstrictor capacitance. Results indicated that chronic cigarette smokers have both reduced vasodilator (P less than 0.01) and reduced vasoconstrictor (P less than 0.02) capacitance when compared with nonsmokers of the same ages regardless of whether or not other risk factors for stroke were present. Vasodilator capacitance to 5 per cent CO2 inhalation was reduced among smokers compared with nonsmokers of the same age by 48 per cent in non-risk subjects and 56 per cent in risk-factored subjects, while vasoconstrictor capacitance to 100 per cent O2 inhalation among smokers was decreased by 24 per cent in non-risk subjects and 34 per cent in risk-factored subjects. In risk-factored subjects, combined effects of smoking and other risks appeared to be additive.

Aged↗

PubMed1984

Effects of aging on cerebral blood flow in dementia.

Regional cerebral blood flow values were measured utilizing the 133Xe inhalation method in patients with multi-infarct dementia (MID) (n = 22, age 67.4 +/- 9.8 years), in patients with senile dementia of Alzheimer type (SDAT) (n = 36, age 63.8 +/- 8.0) and in age-matched normal healthy volunteers (n = 50, age 67.5 +/- 9.3). Mean hemispheric gray matter flow values were significantly reduced in MID (P less than 0.01) and SDAT (P less than 0.01) patients compared with age-matched normal volunteers. In normal volunteers, mean flow values showed gradual declines with advancing age (r = -0.44, P less than 0.005). In MID patients there were significant decreases in flow values with advancing age (r = -0.43, P less than 0.05), but flow values were consistently lower than in age-matched normals. Reductions of flow were most evident in the distribution of both middle cerebral arteries. Unlike MID patients, patients with SDAT had diffusely reduced flow values over all age ranges without correlation with advancing age. Reductions of mean flow values in both dementia groups were significantly correlated with severity of dementia (P less than 0.05 for both groups). Cerebral blood flow reductions related to the aging process also contribute to decreased cerebral perfusion in patients with MID. This is not true in SDAT, where the disease process itself pre-empts cerebral blood flow reductions attributable to aging.

Age Factors↗

PubMed1984

Cerebral blood flow changes in benign aging and cerebrovascular disease.

Cross-sectional analysis of CBF values was carried out among 668 volunteers and patients. Subjects were subdivided according to age, gender, and degree of cerebrovascular disease, ranging from healthy volunteers with or without risk factors for stroke to patients with multi-infarct dementia. Four-year longitudinal analysis was also carried out on 230 individuals from the original sample. Decrements in CBF values were evidenced by both cross-sectional and longitudinal analysis in relation to advancing age, progressive cerebrovascular disease, and dementia. Regional, age-related CBF declines in healthy volunteers were heterogeneous, possibly related to changes in levels of functional activity within different brain regions.

Aged↗

PubMed1983

Cigarette smoking decreases cerebral blood flow suggesting increased risk for stroke.

Effects of chronic cigarette smoking on cerebral blood flow were investigated by measuring gray matter blood flow (Fg) using xenon 133 inhalation among 192 volunteers without cerebrovascular symptoms. There were 108 normal, healthy volunteers; 84 had risk factors for stroke (hypertension, hyperlipidemia, diabetes mellitus, and/or heart disease). Of both risk and nonrisk groups, 75 were habitual smokers (0.5 to 3.5 packs per day for 25 years). Comparisons of mean Fg values for both hemispheres showed significant reductions related to tobacco consumption and risk factors for stroke. Multiple-regression equations using smoking, age, risk, and alcohol consumption indicated a combined R2 value of 0.22. Smoking seems to be a potent risk factor decreasing cerebral blood flow probably by enhancing cerebral arteriosclerosis. Chronic cigarette smoking in persons with other risk factors further reduced Fg values in an additive manner when compared with subjects who had corresponding risk factors who did not smoke.

Cerebrovascular Circulation↗