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Biomedical subjects

R C Petersen

Publications and source records attributed to R C Petersen.

At least 91 records · Page 5Linked to original sources
PubMed1997

Autonomic failure in Guamanian neurodegenerative disease.

Autonomic impairment is minor in idiopathic amyotrophic lateral sclerosis (ALS) and Alzheimer's-type dementia (D) and is usually not marked in Parkinson's disease. The autonomic status of Guamanian parkinsonism (P), ALS, and parkinsonism-dementia complex (PDC) is essentially unknown. We therefore evaluated the autonomic nervous system in Guamanian D, ALS, P, and PDC. Cardiovagal, adrenergic, and postganglionic sudomotor functions were quantitated in 16 patients and 14 paired household controls. Patients comprised PDC (N = 11), D (N = 2), P (N = 2), and ALS (N = 1). Autonomic deficit was expressed on a composite autonomic scoring scale (CASS) and its subsets that corrects for the effects of age and gender. CASS severity was rated from 0 to 10 and the maximal subset scores were 3, 3, and 4 for postganglionic sudomotor, cardiovagal, and adrenergic deficits, respectively. CASS scores for mild, moderate, and severe autonomic failure are 1 to 3, 4 to 6, and 7 to 10, respectively. Symptoms were scored by an Autonomic Symptom Profile (ASP). The affected patients were older than and had a sex distribution different from paired controls (64.2 +/- 8.0 versus 53.1 +/- 13.5; p < 0.01; male/female = 9/7 versus 2/12; p = 0.045). CASS scores were markedly increased over paired controls (6.2 +/- 2.3 versus 1.9 +/- 1.3; p < 0.001), and involvement was generalized by system. There were deficits in sudomotor, cardiovagal, and adrenergic function. Orthostatic hypotension occurred in 6 of 16 patients and 2 of 14 paired controls. Guamanian patients had more autonomic dysfunction than non-Guamanian Parkinson's disease. ASP scores were higher in patients than controls and regressed with CASS. These differences persisted when corrected for the confounding effects of age, gender, and diabetes. We conclude that Guamanian patients have autonomic failure to a greater extent than non-Guamanian Parkinson's disease or ALS. This autonomic failure suggests multisystem autonomic involvement similar to but less severe than in multiple system atrophy.

Adult↗
PubMed1997

Development of cognitive instruments for use in clinical trials of antidementia drugs: additions to the Alzheimer's Disease Assessment Scale that broaden its scope. The Alzheimer's Disease Cooperative Study.

The cognitive assessment protocol of the Alzheimer's Disease Cooperative Study (ADCS) was designed to evaluate the reliability and validity of cognitive assessment measures that might be valuable additions to the Alzheimer's Disease Assessment Scale (ADAS) or other concise batteries used in antidementia drug trials. As part of an overall ADCS protocol to develop new instruments to be used in trials of treatments for Alzheimer's disease (AD), patients with mild to moderate AD and cognitively normal elderly were administered a battery of five tests at least three times over 1 year. The tests included word list learning with delayed free recall, a recognition memory test for faces, a series of letter and digit cancellation tests to measure concentration, tests of praxis, and a series of maze completion tasks designed to assess planning and executive function. A version of the digit cancellation task was reliable and sensitive to a broad range of dementia severity so that it could provide a useful addition to the present version of the ADAS. Performance on the word learning task with delayed recall and a subset of the mazes task were impaired even in mild AD, so these tasks may be useful in trials involving mild or at-risk subjects. Performances on the facial recognition task and on the praxis tasks were not related to dementia severity, so these tasks would not be useful to evaluate treatments. Therefore, the major outcome of this investigation was the identification of some potential additions to the present ADAS that extend both the cognitive domains and the range of symptom severity covered.

Aged↗
PubMed1996

Predictive value of APOE genotyping in incipient Alzheimer's disease.

The Mayo Alzheimer's Disease Center/Alzheimer's Disease Patient Registry is a prospective, longitudinal project of aging and dementia in a community setting. Over 400 pairs of individuals have been studied through this project, and extensive data on clinical, radiological, neuropathological, and biological variables have been gathered. Previous case-control studies on this group of subjects have documented the role of the apolipoprotein E (APOE) epsilon 4 as a risk factor for dementia. Subsequent analyses between APOE and the age of the patients with dementia have shown that most of the epsilon 4 effect is manifest in subjects under 75 years of age. We have also used this patient resource to study a group of individuals who are at risk for dementia by virtue of having a significant memory impairment. We have designated these patients as having a mild cognitive impairment because they have abnormal memory function but do not reach criteria for dementia. Over the course of several years of follow-up, these subjects evolve to dementia at a rate of approximately 15% per year. The presence of an APOE epsilon 4 carrier status is the best predictor of subsequent development of dementia in these individuals. These studies indicate that APOE is an important risk factor for AD, and in patients with a mild cognitive impairment, APOE may be useful in predicting who is likely to progress to dementia.

Aged↗
PubMed1996

Plasma catechols and monoamine oxidase metabolites in untreated Parkinson's and Alzheimer's diseases.

Prior studies have documented functional and pathological compromise of the peripheral sympathetic nervous system in patients with Parkinson's disease, suggesting the possibility of reduced catecholamine release into the circulation. We measured free plasma catechols in early and untreated patients with Parkinson's disease, but found no evidence of reduced concentrations, compared to control subjects or a group of patients with probable Alzheimer's disease. Rather, there was a significant elevation of plasma norepinephrine within the Parkinson's disease group. Furthermore, 6 of 15 untreated Parkinson's disease patients (40%) displayed markedly elevated plasma concentrations of the catecholamine MAO metabolites, DOPAC or DOPEG. Despite this finding, platelet MAO-B activity measured in these and all other Parkinson's disease patients fell well within the range of the control subjects, and was also statistically similar to the group with Alzheimer's type dementia. Plasma dopa levels were similar in all groups, whereas the majority of patients in the three groups had plasma free dopamine and epinephrine concentrations below the limits of detection. These trends toward increased, rather than decreased, circulating catechol concentrations suggest that peripheral sympathetic nervous system catecholamine production and release is not severely compromised in patients with early Parkinson's disease. In addition, we were unable to confirm certain previous reports of elevated MAO-B activity in patients with Parkinson's or Alzheimer's diseases.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1996

Subjective memory complaints, psychological distress, and longitudinal change in objective memory performance.

Between 1992 and 1993, the Memory Function Questionnaire General Frequency of Forgetting Scale (MFQ-GEN), the Symptom Checklist-90-Revised General Severity Index (GSI), and Mayo Cognitive Factor Scales Learning and Retention (MCFS-LRN and MCFS-RET) current and change scores were obtained for 294 of 397 (74%) participants, ages 55-97 years, originally assessed in a 1988-1990 normative study. In multiple regression modeling, the GSI and MCFS-LRN current score contributed 20% and 3%, respectively, to MFQ-GEN variance. Thus, emotional status was a better predictor of subjective memory ratings than either absolute objective memory performance or objective longitudinal memory change. Persons who developed cognitive impairment over the longitudinal interval reported greater memory problems, but memory complaints had little sensitivity in identifying these persons. In an approximate census sample of these older people, minor memory problems were reported to be frequent but not serious.

Aged↗
PubMed1996

A 1-year multicenter placebo-controlled study of acetyl-L-carnitine in patients with Alzheimer's disease.

A 1-year, double-blind, placebo-controlled, randomized, parallel-group study compared the efficacy and safety of acetyl-L-carnitine hydrochloride (ALCAR) with placebo in patients with probable Alzheimer's disease (AD). Subjects with mild to moderate probable AD, aged 50 or older, were treated with 3 g/day of ALCAR or placebo (1 g tid) for 12 months. Four hundred thirty-one patients entered the study, and 83% completed 1 year of treatment. The Alzheimer's Disease Assessment Scale cognitive component and the Clinical Dementia Rating Scale were the primary outcome measures. Overall, both ALCAR- and placebo-treated patients declined at the same rate on all primary and most secondary measures during the trial. In a subanalysis by age that compared early-onset patients (aged 65 years or younger at study entry) with late-onset patients (older than 66 at study entry), we found a trend for early-onset patients on ALCAR to decline more slowly than early-onset AD patients on placebo on both primary endpoints. In addition, early-onset patients tended to decline more rapidly than older patients in the placebo groups. Conversely, late-onset AD patients on ALCAR tended to progress more rapidly than similarly treated early-onset patients. The drug was very well tolerated during the trial. The study suggests that a subgroup of AD patients aged 65 or younger may benefit from treatment with ALCAR whereas older individuals might do more poorly. However, these preliminary findings are based on past hoc analyses. A prospective trial of ALCAR in younger patients is underway to test the hypothesis that young, rapidly progressing subjects will benefit from ALCAR treatment.

Acetylcarnitine↗
PubMed1996

The Mini-Mental State Examination in general medical practice: clinical utility and acceptance.

OBJECTIVE: To examine the psychometric properties, acceptance, and screening efficacy of the Mini-Mental State Examination (MMSE) in an internal medicine practice. MATERIAL AND METHODS: The MMSE was administered more than 4,000 times by 27 internists to 3,513 elderly patients (2,299 women and 1,214 men, 60 to 102 years old) who underwent general medical examinations. The efficacy of the MMSE for screening was measured in a subsample of age- and sex-matched patients with dementia (N = 185) and control subjects (N = 227). MMSE scores were correlated with age and education in the community sample. The attitudes of physicians about the MMSE were assessed with a 12-question survey. Sensitivity, specificity, and predictive values were calculated. RESULTS: Performance on the MMSE among persons older than 59 years was influenced by age and education but not by sex. During an interval of 1 to 4 years, a change of 4 or more points in the total MMSE score is needed to indicate substantial cognitive deterioration. Participating physicians considered the MMSE of little value for routine screening in unselected populations but wanted it available for use as a clinical test. The traditional MMSE cutoff score of 23 or less had a sensitivity of 69% and a specificity of 99%. Use of age- and education-specific cutoff scores improved the sensitivity to 82% with no loss of specificity. With use of typical base rates for dementia in a general medical practice, the positive predictive value was less than 35%. CONCLUSION: The clinical utility of the MMSE and acceptance by physicians may be improved through awareness of the influences of age and education on the MMSE and by its application in settings with a high base rate of dementia. The MMSE is ineffective when used to screen unselected populations; it should be used for persons at risk of cognitive compromise.

Age Factors↗
PubMed1995

Apolipoprotein E status as a predictor of the development of Alzheimer's disease in memory-impaired individuals.

OBJECTIVE: The outcome of patients with mild cognitive impairment is not known, yet these patients present a difficult dilemma for the clinician. This study was designed to characterize the outcome of a group of patients with mild cognitive impairment and to determine whether the presence of the epsilon 4 allele on the apolipoprotein E gene (APOE) is a predictor of that outcome. DESIGN: A prospective, longitudinal inception cohort. SETTING: General community clinic. PARTICIPANTS: A consecutive sample of 66 patients who met criteria for a diagnosis of a mild cognitive impairment and who had at least one clinical reevaluation was identified from the Mayo Clinic Alzheimer's Disease Center/Alzheimer's Disease Patient Registry. INTERVENTIONS: We evaluated patients initially and at 12- to 18-month intervals up to 54 months using standard neurological and neuropsychological measures such as the Mini-Mental State Examination, the Dementia Rating Scale, the Wechsler Adult Intelligence Scale--Revised, the Wechsler Memory Scale--Revised, and the Free and Cued Selective Reminding Test. The APOE status of study patients was determined. MAIN OUTCOME MEASURE: The development of dementia as determined by the Diagnostic and Statistical Manual of Mental Disorders, Revised Third Edition and the National Institute of Neurological and Communicative Disorders and Stroke/Alzheimer's Disease and Related Disorders Association criteria. RESULTS: Sixty-six individuals had been reevaluated once (mean of 18 months), 36 individuals twice (mean of 36 months), and 22 individuals on three occasions (mean of 54 months), with conversion rates to dementia at these intervals of 24%, 44%, and 55%, respectively. A multivariate Cox regression model demonstrated that possession of an APOE epsilon 4 allele was the strongest predictor of clinical outcome. CONCLUSIONS: These data suggest the following: (1) patients with mild cognitive impairment can be clinically defined, (2) many members of this group progress to Alzheimer's disease, and (3) APOE epsilon 4 allele status appears to be a strong predictor of clinical progression.

Aged↗
PubMed1995

No evidence for systemic oxidant stress in Parkinson's or Alzheimer's disease.

Oxidant stress secondary to dopamine metabolism has been proposed as a pathogenic factor in the development of Parkinson's disease. Biochemical abnormalities extending beyond the central nervous system have been identified in patients with this condition. Previous investigators have found abnormally elevated concentrations of the lipid peroxidation product, malondialdehyde, in the plasma and serum of patients with Parkinson's disease. We attempted to replicate these findings but controlled for other factors that could influence malondialdehyde levels. We detected no significant elevations in mean serum malondialdehyde concentrations in either levodopa-treated or untreated patients with Parkinson's disease, compared to normal controls; similarly, no elevation was found in a group of patients with dementia of Alzheimer's type. On the other hand, a group of subjects with diabetes mellitus but no neurodegenerative disease had significantly elevated mean serum malondialdehyde levels, consistent with previous studies of diabetic patients. Autoxidation is one of the two major routes by which dopamine and dopa metabolism may generate oxygen free radicals. We analyzed the autoxidation product of dopa, 5-S-cysteinyl-dopa, in the plasma of these same groups of patients with neurodegenerative disease and normal controls; no significant differences were identified. Serum concentrations of two other antioxidant substances, alpha-tocopherol and uric acid, were also statistically similar in these groups. In conclusion, analysis of several blood products relevant to oxidant stress, including malondialdehyde, 5-S-cysteinyl-dopa, alpha-tocopherol, and uric acid, failed to distinguish patients with Parkinson's disease or dementia of Alzheimer's type from controls.

Aged↗
PubMed1995

Guamanian neurodegenerative disease: investigation of the calcium metabolism/heavy metal hypothesis.

OBJECTIVE: There is a high prevalence of neurodegenerative disease (parkinsonism, dementia, and motor neuron disease) on the western Pacific island of Guam. We sought evidence in support of the hypothesis that these conditions are triggered by nutritional deficiencies of calcium and magnesium leading to secondary hyperparathyroidism that then facilitates the entry of calcium and toxic heavy metals into the brain. METHODS: We analyzed indices of calcium metabolism plus blood-serum, urine, nail, and hair heavy metal concentrations in 12 patients with Guamanian neurodegenerative disease and 12 Chamorro control subjects. RESULTS: All 12 patients with Guamanian neurodegenerative disease had normal values for serum total and ionized calcium, 25-hydroxyvitamin D, and 24-hour urine collections for calcium. Eleven of 12 patients had normal serum parathyroid hormone values and alkaline phosphatase levels. No patient had reduced serum phosphorus or magnesium values although a minority of patients and controls had low urinary magnesium concentrations. Median blood-serum and 24-hour urine collections for heavy metals (aluminum, arsenic, cadmium, copper, iron, lead, manganese, mercury, and zinc) were statistically similar in the patient and control groups except for a slight elevation of blood, but not urine, lead in the patient group. Concentrations of heavy metals in hair and nails were similar in the two groups. CONCLUSIONS: We could find no evidence in support of abnormalities of calcium metabolism or heavy metal absorption as a major causative factor in the development of neurodegenerative disease on the island of Guam.

Aged↗
PubMed1995

Dementia: diagnosis and evaluation.

OBJECTIVE: To describe an approach to the diagnosis of dementia based on effective assessment methods. DESIGN: We reviewed the literature and summarized the available diagnostic and prognostic studies of dementia that may be useful to the primary-care physician. RESULTS: Although controversy exists about certain aspects of the diagnostic workup, exclusion of potentially reversible causes of dementia is essential. Laboratory studies (for example, for detection of underlying metabolic abnormalities) and neuroimaging of the brain may be useful. The pattern of onset and the temporal course of the disease may suggest a cause and help direct the investigation. Functional losses can substantially impair the patient's ability to live independently. CONCLUSION: Dementia can be mistakenly considered as part of the normal aging process, and diagnosis necessitates a thorough, although not exhaustive, approach. Early identification of dementing illnesses improves the outcome for reversible disease and may also enhance the management of incurable dementias.

Dementia↗
PubMed1994

Patterns and predictors of institutionalization in community-based dementia patients.

OBJECTIVE: To investigate patterns and predictors of institutionalization in a community-based sample of dementia patients. SETTING: The Mayo Clinic Alzheimer's Disease Patient Registry (ADPR), a community-based prospective registry. PATIENTS: Two hundred seventy-five participants, including 145 dementia patients and 130 controls on whom longitudinal follow-up data was available. The mean ages were 79.9 and 78.8 years, and the mean Mini-Mental State Examination (MMSE) scores at enrollment were 22.1 and 28.1 points for the demented cases and controls, respectively. MEASURES: Place of residence, marital status, number of direct support providers, global cognitive status, activities of daily living and instrumental activities of daily living were used in hazards modeling of institutionalization. RESULTS: The results from our community-based sample suggest a high rate of institutionalization for dementia patients. One-half of the sample of dementia patients were institutionalized within 2.5 years of enrollment in our patient registry. Identified assistance providers were absent in a significant proportion (36%) of our dementia sample. Marital status, global cognitive function, and functional status were significant terms in hazards models of institutionalization. Age, gender, number of direct caregivers, and dementia etiology were not associated with significant risk. Seventy-two percent of the dementia patients who died over the course of this study had been placed in nursing home care prior to death (with a mean length of stay of 2.8 years). CONCLUSIONS: Social (marital status) and disease-related variables (cognitive and functional status) are related to risk for institutionalization. These variables may be useful in estimating time to institutionalization in various clinical and research populations.

Aged↗
PubMed1994

Memory function in very early Alzheimer's disease.

The detection of very early Alzheimer's disease (AD) can be important for both theoretical and practical reasons. Typically, a memory impairment is the first sign of incipient disease, but the early clinical diagnosis can be challenging. We investigated several aspects of memory function in AD and normal aging to determine which indices of performance were most sensitive at detecting early impairments. We evaluated 106 pairs of patients with probable AD and matched controls from the Mayo Clinic Alzheimer's Disease Patient Registry using a logistic regression model that included measures of memory function, verbal and nonverbal intelligence, attention, and language. Results indicated that an index of learning, especially with semantic cuing, was most sensitive at separating the two groups. We then matched subsets of individuals from the larger groups of AD and control subjects on the Mini-Mental State Examination (range of scores, 24 to 26). A logistic regression analysis on these matched groups yielded the same results. A measure of learning with facilitation of performance using cues appears to be the best discriminator at detecting very mild AD. These measures can be useful in selecting patients for interventional strategies.

Aged↗
PubMed1994

Apolipoprotein E: risk factor for Alzheimer disease.

The apolipoprotein E gene (APOE) has three common alleles (epsilon 2, epsilon 3, and epsilon 4) that determine six genotypes in the general population. In this study, we examined 77 patients with late-onset Alzheimer disease (AD), along with an equal number of age- and sex-matched controls, for an association with the APOE-epsilon 4 allele. We show that the frequency of this allele among AD patients was significantly higher than that among the control population (.351 vs. .130, P = .000006). The genotype frequencies also differed between the two groups (P = .0002), with the APOE-epsilon 4/epsilon 3 genotype being the most common in the AD group and the APOE-epsilon 3/epsilon 3 being the most common in the control group. In the AD group, homozygosity for epsilon 4 was found in nine individuals, whereas none was found in the control group. The odds ratio for AD, when associated with one or two epsilon 4 alleles, was 4.6 (95% confidence interval [CI] 1.9-12.3), while the odds ratio for AD, when associated with heterozygosity for APOE-epsilon 4, was 3.6 (95% CI 1.5-9.8). Finally, the median age at onset among the AD patients decreased from 83 to 78 to 74 years as the number of APOE-epsilon 4 alleles increased from 0 to 1 to 2, respectively (test for trend, P = .001). Our data, which are in agreement with recent reports, suggest that the APOE-epsilon 4 allele is associated with AD and that this allelic variant may be an important risk factor for susceptibility to AD in the general population.

Age of Onset↗