Biomedical subjects

G van Belle

Publications and source records attributed to G van Belle.

At least 37 records · Page 2Linked to original sources

PubMed1997

Behavioral changes following participation in a home health promotional program in King County, Washington.

This study examined behavioral changes in households after participation in a home environmental assessment. Home assessment visits by a trained coach, which involved a walk-through in the home with the home residents, were conducted in 36 homes. The walk-through included a list of recommended behavioral changes that the residents could make to reduce their exposures to home pollutants in areas such as dust control, moisture problems, indoor air, hazardous household products, and hobbies. Recruited households were surveyed 3 months after the home assessment to evaluate their implementation of the recommendations. Following the home visits, 31 of 36 households reported making at least one behavioral change, and 41% of the recommendations made by the volunteer coaches were implemented. In conclusion, this study found that the majority of the households who participated in the home assessment reported implementing at least one recommendation. This home health promotional method was effective in influencing behavioral changes.

Feedback↗

PubMed1997

Consortium to establish a registry for Alzheimer's disease: development, database structure, and selected findings.

The Consortium to Establish a Registry for Alzheimer's Disease (CERAD) was funded in 1986 by the National Institute on Aging to develop standardized assessments for patients with Alzheimer's disease (AD). Since that time, CERAD has developed and evaluated clinical and neuropsychological test batteries, a neuroimaging protocol, and an assessment of the neuropathological findings of the brains of these patients at autopsy. Approximately 1,200 carefully screened patients with AD and 450 control subjects were evaluated using these instruments at 24 major medical centers around the United States. Annual follow-up observations of these subjects were made for up to eight years. Autopsy examinations of the brain were done in over half of the deceased cases and the clinical diagnosis of AD was confirmed in 85 percent of them. This article outlines the procedures used for identifying the clinical sites, the entry and annual evaluations of patients and control subjects, the collection and analysis of data at a central Methodology and Data Management Center, and evaluation of the CERAD measures. We also present selected data from the 50 or so peer-reviewed papers published to date, with particular emphasis on findings from African-American patients with AD, and related policy implications.

Aged↗

PubMed1996

Randomized trial of leaving messages on telephone answering machines for control recruitment in an epidemiologic study.

To determine whether leaving messages on answering machines would aid control recruitment via random-digit telephone dialing, a randomized trial was conducted during 1992-1994 involving 1,323 western Washington households with answering machines. For the experimental group, a message was left informing them about the study and promising a call-back; for the control group, no message was left. Leaving a message increased the response rate by about 20 percentage points (p = 0.002). More households were successfully screened for eligible controls, and individuals found eligible were more likely to participate. Leaving a message can help to improve response rates in telephone surveys.

Adult↗

PubMed1996

Incidence of amyotrophic lateral sclerosis in three counties in western Washington state.

We conducted a population-based study of amyotrophic lateral sclerosis (ALS) in King, Pierce, and Snohomish counties in western Washington state. Between April 1, 1990 and March 31, 1995, neurologists diagnosed 235 patients with ALS, including 127 men (54%) and 108 women (46%). The incidence rate, age-adjusted to the 1990 total U.S. population, was higher for men at 2.1 per 100,000 per year (95% CI, 1.3 to 2.9) than for women at 1.9 (95% CI, 1.1, 2.7) and increased with age for both men and women. These incidence rates are consistent with other studies from northern latitudes.

Adult↗

PubMed1995

Solvent exposure as a risk factor for Alzheimer's disease: a case-control study.

This case-control study investigates whether history of organic solvent exposure is associated with increased risk of Alzheimer's disease. The study base includes about 23,000 persons aged 60 years or more from the local membership of a health maintenance organization in Seattle, Washington, who entered the study between 1987 and 1992. Probable Alzheimer's disease cases (n = 193) who had presented with new dementia symptoms were identified, enrolled, and diagnosed by our Alzheimer's Disease Patient Registry following standardized criteria. Control subjects (n = 243), free of dementia and neurologic disease causing dementia, were selected randomly from the study base and frequency matched to cases for age and sex. Proxy informants provided specific solvent exposure history as well as job descriptions likely to involve solvent use as part of a comprehensive risk factor interview. Kappa statistics indicated substantial agreement for control-control proxy solvent responses. History of exposure to one or more solvent groups (benzene and toluene; phenols and alcohols; ketones; other solvents) yielded an adjusted Alzheimer's disease odds ratio of 2.3 (95 percent confidence interval 1.1-4.7); among males only, it increased to 6.0 (95% confidence interval 2.1-17.2). Thus, past exposure to organic solvents may be associated with onset of Alzheimer's disease.

Age Factors↗

PubMed1995

The effect of diagnosing Alzheimer's disease on frequency of physician visits: a case-control study.

OBJECTIVE: Two groups of elderly subjects were studied to see whether patterns of visits to physicians changed after one group received the diagnosis of Alzheimer's disease. DESIGN: Case-control study. SETTING: Health maintenance organization (HMO). PATIENTS/PARTICIPANTS: Two groups of ambulatory subjects (mean age 77 years) were enrolled from an HMO population for this case-control study: 120 cases had probable Alzheimer's disease diagnosed at enrollment, and another 120 cognitively intact controls with similar comorbidity were enrolled after being frequency-matched for age and gender. Exclusion criteria were nursing home admission and death during the study period. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Medical records were examined for a four-year period: two years prior to and two years following enrollment and diagnosis. Physician visits declined slightly after enrollment for the persons receiving the diagnosis of Alzheimer's disease [17.5/2 years prior vs 16.5/2 years after (NS)], whereas visits increased over time for the controls [13.7/2 vs 16.3/2 (p < 0.05)], hence the rates were similar after enrollment [16.5 vs 16.3 (NS)]. The proportion of subjects with fewer visits during the period after enrollment was higher among the cases than it was among the controls [54% vs 37%; odds ratio = 2.0 (95% confidence interval = 1.6, 3.1)]. Hospitalizations and emergency department use did not change significantly after enrollment. CONCLUSIONS: Physician visit frequency was high before, then decreased after, demented patients received their diagnosis, approaching the frequency in a control population without dementia. This phenomenon cannot be accounted for by nursing home placement, comorbidity, or mortality. Increased hospitalization and emergency department use did not ensue after diagnosis.

Aged↗

PubMed1995

Lack of cholinergic regulation of vasopressin and norepinephrine responses to hypertonic saline in humans.

In vitro studies in hypothalamic-pituitary explants in the rat have suggested cholinergic mediation of arginine vasopressin (AVP) osmoregulation. In this study we attempted to demonstrate, in humans, cholinergic mediation of AVP osmoregulation. Specifically, we tested the hypothesis that the plasma AVP response to an osmolar stimulus would be attenuated by pharmacologic blockade of central nervous system muscarinic or nicotinic receptors in humans. We also evaluated the effects of cholinergic blockade on the norepinephrine (NE) response to an osmolar stimulus. Young normal males underwent hypertonic saline infusion following administration of the centrally active muscarinic antagonist scopolamine or the centrally active nicotinic antagonist mecamylamine. Neither mecamylamine nor scopolamine affected the AVP response to hypertonic saline infusion. Mecamylamine reduced NE concentrations in a dose-dependent manner, but did not affect the slope of the NE increase during hypertonic saline infusion. In a second experiment, we evaluated the effects of scopolamine and mecamylamine on the AVP and NE responses to physostigmine, a cholinesterase inhibitor which stimulates AVP release into plasma through a non-osmolar central nervous system cholinergic mechanism. Scopolamine eliminated the AVP response to physostigmine. Mecamylamine reduced NE concentrations both before and after scopolamine administration but did not affect the slope of the AVP response. These results fail to support cholinergic regulation of the AVP response to osmolar stimulation in humans.

Adult↗

PubMed1995

Geographically overlapping Alzheimer's disease registries: comparisons and implications.

In the medical and epidemiologic literature, a registry denotes a data base in which registrants share some common characteristic such as disease category. One criticism of registries is that they frequently collect subjects in a haphazard fashion and, hence, are "nonrepresentative of the population purportedly being represented." In this report, we compare two registries: an incident-based Alzheimer's Disease Patient Registry (ADPR) recruiting subjects for epidemiologic studies from a large health maintenance organization; and an Alzheimer's Disease Research Center (ADRC) registry recruiting subjects for phenomenologic, biologic, and pharmacologic studies. While these registries share personnel, overlap geographically, and use similar diagnostic procedures, they differ substantially in their missions and resulting recruitment strategies. We compared these registries with respect to demographic characteristics and cognitive features at subject entry. Subjects enrolled in the incident-based registry are older and report shorter time between symptom onset and recruitment. They are less demented and mirror the general population demographically more closely than do subjects in the other registry. The ADRC registry contains a much greater proportion of subjects with higher educational attainment.

Age Factors↗

PubMed1994

Postmenopausal estrogen replacement therapy and the risk of Alzheimer's disease: a population-based case-control study.

Preliminary animal and human data suggest that estrogens may be protective against Alzheimer's disease in women. In a population-based case-control study at Group Health Cooperative of Puget Sound, Seattle, Washington, the authors compared the exposure of estrogen replacement therapy of 107 female Alzheimer's disease cases with 120 age- and sex-matched controls by using computerized pharmacy data. The cases were obtained from the Alzheimer's Disease Patient Registry of the University of Washington, Seattle, Washington, which is based on the enumerated health plan population from 1987 to 1992. Newly recognized cases of probable Alzheimer's disease according to standardized diagnostic criteria were ascertained, evaluated, and enrolled in the Registry. The controls were selected from the same defined population by stratified random sampling. When the authors applied logistic regression, ever use of estrogens did not show an association with Alzheimer's disease (adjusted odds ratio = 1.1, 95 percent confidence interval 0.6-1.8). Oral and vaginal estrogens yielded similar results. In conclusion, this study provides no evidence that estrogen replacement therapy has an impact on the risk of Alzheimer's disease in women.

Administration, Intravaginal↗

PubMed1994

Subarachnoid hemorrhage and hormonal factors in women. A population-based case-control study.

OBJECTIVE: To determine the degree to which endogenous and exogenous hormonal factors influence the risk for subarachnoid hemorrhage in women. DESIGN: A population-based case-control study. SETTING: King County, Washington. PARTICIPANTS: 103 women with an incident, spontaneous subarachnoid hemorrhage and 2 age- and sex-matched controls per case-patient who were identified through random-digit dialing. MEASUREMENTS: Information on exposures was collected during in-person interviews of case-patients, controls, and their surrogates. RESULTS: Premenopausal women, especially those without a history of smoking or hypertension, were at a reduced risk for subarachnoid hemorrhage compared with age-matched postmenopausal women (odds ratio, 0.24; 95% CI, 0.09 to 0.68). The use of hormone replacement therapy was associated with a reduced risk (odds ratio, 0.47; CI, 0.26 to 0.86); the reduction was significantly greater in women who had smoked than in those that had never smoked. Of the 23 premenopausal case-patients, 74% were either menstruating when hemorrhaging occurred or had had their last menstrual period 21 or more days before hemorrhaging compared with the expected 43% (difference, 31%; CI, 4% to 58%). CONCLUSIONS: Premenopausal women are at reduced risk for subarachnoid hemorrhage, especially those without a history of smoking or hypertension. Hormone replacement therapy reduced the risk only in postmenopausal women who had ever smoked. Among women still menstruating, the risk for hemorrhage was greatest in the perimenstrual period.

Adult↗

PubMed1994

Completeness and accuracy of interview data from proxy respondents: demographic, medical, and life-style factors.

To evaluate the quality of exposure data provided by proxy respondents, we used a dual interview protocol in a case-control study of subarachnoid hemorrhage. All control subjects and their proxy respondents were interviewed (N = 283 control-proxy pairs), as were the cases who were able to provide their own information and their proxy respondents (N = 68 case-proxy pairs). The reliability of proxy-derived data was excellent for demographic and body habitus measures (kappa or intraclass correlation range = 0.86-0.99), and all aspects of cigarette smoking history (range = 0.79-0.93). Proxy reliability was somewhat lower for questions regarding medications and hormone preparations (range = 0.55-0.88), alcohol consumption (range = 0.52-0.82), and recreational physical activity (range = 0.55-0.67). Proxy reliability varied according to the relationship of the proxy to the index subject. Relative to the index subjects, proxy respondents tended to underreport the presence or level of exposure. For most exposures, odds ratios computed with proxy-derived data were similar in magnitude to odds ratios obtained with index subject data; important bias due to differential nonresponse or differential misclassification was suggested only for questions regarding hormone replacement therapy. Epidemiologic studies that rely on proxy respondents may require more subjects to offset the effect of nondifferential nonresponse and misclassification on the precision of effect estimates.

Adolescent↗

PubMed1994

Interlaboratory comparison of neuropathology assessments in Alzheimer's disease: a study of the Consortium to Establish a Registry for Alzheimer's Disease (CERAD)

Concerns about intercenter variation in methods and interpretation prompted CERAD investigators to examine standardization of the neuropathological assessment of Alzheimer's disease (AD). Contiguous frontal lobe sections derived from autopsy brains of eight patients clinically diagnosed as having probable AD and two cognitively normal individuals were distributed to 24 neuropathologists from 18 medical centers in the United States and Canada. Using their routine staining method(s), neuropathologists determined the rank order of severity of AD neuropathology in these cases, as well as semiquantitative and quantitative senile plaque and neurofibrillary tangle frequencies. Ranking of the ten cases revealed 75% inter-rater reliability among the 24 raters. Semiquantitative analyses showed reasonable inter-rater agreement, whereas quantitative measures yielded significant differences between raters for plaque and tangle counts (p < 0.0001). These differences reflected variation in stain sensitivity, staining technique (even when the same stain was used), and interpretation of the histological findings. Ratings on the cases with the highest proportions of diffuse plaques showed the greatest dependence upon stain sensitivity and variability in interpretation. This study indicates that greater attention to quality improvement is needed for the neuropathological evaluation of AD, particularly when pooling data in multicenter studies such as CERAD.

Aged↗

PubMed1994

Symptom patterns and comorbidity in the early stages of Alzheimer's disease.

OBJECTIVE: To learn whether patients with early Alzheimer's disease tend to under-report or over-report symptoms and to compare their comorbidity with non-demented patients. DESIGN: Case Control Study in a population-based dementia registry. SETTING AND PATIENTS: Three groups of subjects (mean age 76) were enrolled from an HMO base population: 154 cases had clinically diagnosed probable Alzheimer's disease, 92 subjects were found to be not demented although they had complaints of cognitive impairment, and another 129 cognitively intact controls were enrolled after frequency-matching for age and sex. MEASUREMENTS AND RESULTS: Medical records were examined for the 2 years prior to enrollment. Symptoms suggestive of cognitive impairment were evident 7.8 months prior to enrollment (median 6 months) in 95% of cases, in 77% of the not demented subjects, and in 6% of controls. After corrections for multiple comparisons, only symptoms of cognitive impairment were more frequent in cases, whereas several common symptoms not suggestive of cognitive impairment (eg, gastrointestinal discomfort, joint pain, vision problems) occurred more often in controls and the not demented group, even though comorbidity was similar among all three groups (Charlson Index mean scores: case = 0.7, not demented = 0.7, control = 0.5). CONCLUSIONS: Persons with Alzheimer's disease do complain of symptoms clearly related to cognitive impairment early in the course of illness, but may under-report common symptoms not suggestive of cognitive impairment, even though their comorbidity is similar to patients without dementia.

Aged↗

PubMed1994

Aspartame ingestion and headaches: a randomized crossover trial.

To examine whether ingestion of aspartame is associated with headaches, we conducted a double-blind crossover study using volunteers with self-identified headaches after using aspartame. Of the 32 subjects randomized to receive aspartame (approximately 30 mg/kg/d) and placebo in a two-treatment, four-period crossover design, 18 completed the full protocol, seven completed part of the protocol before withdrawing due to adverse effects, three withdrew for other reasons, two were lost to follow-up, one was withdrawn due to noncompliance, and one withdrew and gave no reason. Each experimental period was 7 days long. Subjects reported headaches on 33% of the days during aspartame treatment, compared with 24% on placebo treatment (p = 0.04). Subjects who were "very sure" prior to the study that aspartame triggered some of their headaches reported larger treatment differences (aspartame = 0.37 headache-days, placebo = 0.18 headache-days; p < 0.001) than subjects who were "somewhat sure" (aspartame = 0.29 headache-days, placebo = 0.22 headache-days; p = 0.51) or "not sure" (aspartame = 0.33 headache-days, placebo = 0.39 headache-days; p = 0.51). There was no significant treatment difference in the length or intensity of headaches or in the occurrence of side effects associated with the headaches. This experiment provides evidence that, among individuals with self-reported headaches after ingestion of aspartame, a subset of this group report more headaches when tested under controlled conditions. It appears that some people are particularly susceptible to headaches caused by aspartame and may want to limit their consumption.

Adult↗

PubMed1993

The consortium to establish a registry for Alzheimer's disease (CERAD). Part IV. Rates of cognitive change in the longitudinal assessment of probable Alzheimer's disease.

Reliable information on rate of progression of cognitive impairment in probable Alzheimer's disease (AD) is important for evaluating possible beneficial effects of therapeutic agents and in planning long-term care for patients with this chronic illness. However, wide variability exists in published rates of change for psychometric measures of the dementing process, and there is need for an accurate analysis of large numbers of persons with the disorder studied over long periods. Utilizing the large, well-characterized sample of the Consortium to Establish a Registry for Alzheimer's Disease and employing a least squares regression method to adjust for different levels of impairment and periods of observation, we report rates of change on the Short Blessed Test, Mini-Mental State Examination, Blessed Dementia Scale, Clinical Dementia Rating, and other cognitive measures in 430 patients with probable AD (mean age at entry = 70.9 +/- 8.0 SD years) studied for up to 4 years. We found that rate-of-change determinations are less reliable when the observation period is 1 year or less, that dementia progression may be nonlinear when described by certain measures, and that simple change scores do not accurately characterize the rate of decline. We also found that rate of progression in AD is determined by the severity of cognitive impairment: the less severe the dementia, the slower the rate of decline.

Aged↗

PubMed1993

Relationship between cigarette smoking and Alzheimer's disease in a population-based case-control study.

We investigated whether cigarette smoking is negatively associated with Alzheimer's disease (AD) in a population-based, frequency-matched, case-control study of 152 AD patients and 180 controls. Ever having smoked was associated with lower risk of AD (adjusted odds ratio = 0.61; 95% confidence interval: 0.37-0.99). Additional multivariate analyses demonstrated that education and history of hypertension modified this association. The direction of the modification was for higher education level and history of hypertension to further reduce the risk. The "dose-response" pattern showed the greatest risk reduction among those who smoked least and suggests a biologic mechanism of a dose-dependent up-regulation of nicotinic (cholinergic) brain receptors. These data, although consistent with current opinion about pathophysiology of AD, do not suggest smoking should be used as a preventive strategy for AD.

Aged↗

PubMed1993

Clinical course of spontaneous subarachnoid hemorrhage: a population-based study in King County, Washington.

Over 2 years, we identified 171 patients in King County, Washington, experiencing an incident subarachnoid hemorrhage and characterized their clinical course and outcome. Most (65%) were women and most (68%) were under age sixty-five. Only five died without medical attention. The remaining 166 patients were hospitalized and had CTs of the head. Of these, 103 underwent aneurysm surgery, 40 developed acute hydrocephalus, 32 had symptomatic vasospasm, and 30 re-bled. Sixty-eight percent (68%) survived to 1 month after the bleed and 62% to 1 year. Independent predictors of good recovery by 1 month after the bleed included youth, a high score on the admission Glasgow Coma Scale, and absence of blood on the first CT. In this population-based series, at 1 month after the bleed, approximately one-third of patients were dead, one-third had neurologic deficits, and one-third were doing well.

Adult↗

PubMed1993

Comparison of the severity of neuropathologic changes in familial and sporadic Alzheimer's disease.

We compared the density of neurofibrillary tangles (NT) and neuritic (senile) plaques (NP) in 10 cortical areas, the amygdala, the hippocampus, the parahippocampal gyrus, and the cerebellum in patients with familial (FAD) and sporadic (SAD) Alzheimer's disease with early (< 55 years), intermediate (55-70 years) and late (> 70 years) ages of onset of dementia and age-matched controls. From a total of 199 cases of pathologically confirmed AD in our laboratory, 60 cases with appropriate brain sections and information as to family history, age of onset, duration of dementia, and brain weight were available for semiquantitative analysis of the frequency of NT and NP utilizing the Consortium to Establish a Registry for Alzheimer's Disease protocol. There were 28 SAD and 32 FAD (including seven Volga Germans) cases and 16 age-matched controls. In all brain regions, cases had more severe changes than controls (p < 0.001). Brain weight correlated inversely with duration of disease (p < 0.001). No significant differences were found in the severity scores of NT and NP between FAD and SAD. There was an inverse correlation between age of onset of dementia and the density of NT and NP in all regions in FAD and SAD combined. P values for NT were in the frontal (superior-middle and orbital, p < 0.0005; gyrus rectus, p = 0.0029), parietal (p = 0.0007), and medial occipital cortex (areas 17 and 18, p < 0.01), and for NP were in the superior temporal gyrus (p = 0.0085) and area 17 (p = 0.0003), and age of onset of dementia. In summary, using these criteria we found no compelling evidence that the neuropathologic characteristics of FAD are different from those of SAD.

Aged↗