Biomedical subjects

R C Petersen

Publications and source records attributed to R C Petersen.

At least 73 records · Page 4Linked to original sources

PubMed1999

Testing normal older people three or four times at 1- to 2-year intervals: defining normal variance.

Normative data were presented that defined the upper and lower standards for deciding if cognitive abilities show reliable change over 2 or more testing occasions when retesting occurs at 1- to 2-year intervals. The Mayo Cognitive Factor Scores (MCFS; G. E. Smith et al., 1994) were analyzed because they permit the quantitation of overall functioning in 5 clinically important cognitive domains: established verbal knowledge, nonverbal reasoning, attention and concentration, new learning, and delayed memory. To the authors' knowledge, this is the first report of both group-level and individual-level data analyses derived from a respectably sized sample of normal persons who have been tested 3 or more times at clinically common test-retest intervals.

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PubMed1998

Association of missense and 5'-splice-site mutations in tau with the inherited dementia FTDP-17.

Thirteen families have been described with an autosomal dominantly inherited dementia named frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17), historically termed Pick's disease. Most FTDP-17 cases show neuronal and/or glial inclusions that stain positively with antibodies raised against the microtubule-associated protein Tau, although the Tau pathology varies considerably in both its quantity (or severity) and characteristics. Previous studies have mapped the FTDP-17 locus to a 2-centimorgan region on chromosome 17q21.11; the tau gene also lies within this region. We have now sequenced tau in FTDP-17 families and identified three missense mutations (G272V, P301L and R406W) and three mutations in the 5' splice site of exon 10. The splice-site mutations all destabilize a potential stem-loop structure which is probably involved in regulating the alternative splicing of exon10. This causes more frequent usage of the 5' splice site and an increased proportion of tau transcripts that include exon 10. The increase in exon 10+ messenger RNA will increase the proportion of Tau containing four microtubule-binding repeats, which is consistent with the neuropathology described in several families with FTDP-17.

Alternative Splicing↗

PubMed1998

Hippocampal atrophy and apolipoprotein E genotype are independently associated with Alzheimer's disease.

A variety of anatomic and functional neuroimaging findings are associated with Alzheimer's disease (AD). One of the strongest imaging associations identified is between AD and hippocampal atrophy. The epsilon4 allele of the apolipoprotein E (ApoE) gene increases the risk of developing AD and lowers the mean age of onset of the disease. The purpose of this study was to assess the association between hippocampal volume and ApoE polymorphisms in elderly control subjects and in patients with probable AD. We performed magnetic resonance imaging-based volume measurements of the hippocampus in 125 cognitively normal elderly controls and 62 patients with probable AD. ApoE genotyping was performed by using standard methods. Hippocampal volumes were significantly smaller in AD cases than in control subjects. Hippocampal volumes did not differ significantly within either clinical group on the basis of ApoE genotype. Both the epsilon4 allele of ApoE and hippocampal atrophy were significantly but independently associated with AD.

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PubMed1998

Mayo's older Americans normative studies: category fluency norms.

Age-adjusted normative data are presented for persons over age 55 years on a common measure of category fluency. Further adjustment for education is also provided. These data were obtained as part of a series of projects known collectively as Mayo's Older Americans Normative Studies (MOANS). The normative information provided here should prove useful for characterizing performance on the individual measure of category fluency. In addition, these data should promote greater accuracy in comparing category fluency scores with performance on any other measures with MOANS norms, including tests of letter fluency. Limitations and unique features of MOANS normative data are also discussed.

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PubMed1998

Normative data for the Mattis Dementia Rating Scale.

Age-adjusted normative data are presented for persons over age 55 on the Mattis Dementia Rating Scale. Additional adjustment for the effect of education on test performance is also provided. These data were collected as part of Mayo's Older Americans Normative Studies (MOANS) in a continuing effort to develop age-appropriate norms for older persons on commonly used neuropsychological tests. The normative data presented here should prove more useful in characterizing the presence and severity of general cognitive dysfunction than currently available norms. Limitations and unique features of MOANS normative data are also discussed.

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PubMed1998

Clinical subtypes of Alzheimer's disease.

Alzheimer's disease (AD) can present as a variety of clinical profiles. Although the most common presentation is that of a progressive amnestic disorder with subsequent involvement of other cognitive functions and personality alterations, there are numerous other clinical profiles. AD can present as a focal cortical degenerative syndrome with the clinical features dependent on the regions of the brain involved. Some of these syndromes include disturbances of language, visuospatial skills, attentional functions, executive processes and praxis. The neuropathological substrate of these disorders is variable and can include AD. Recently, the Lewy body variant of AD has been described. Finally, other modifying features that affect the progression of AD, such as extrapyramidal symptoms and myoclonus, are also discussed. Although the progressive amnestic form of AD is the most common presentation, other variations on the clinical syndrome can be important to identify because they may have implications for prognosis and treatment.

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PubMed1998

Apolipoprotein E genotype influences cognitive 'phenotype' in patients with Alzheimer's disease but not in healthy control subjects.

We examined the association of apolipoprotein E (apo E) genotype with cognitive performance in Alzheimer's disease (AD) and Mild Cognitive Impairment (MCI) patients and in normal subjects. One hundred fifty-seven AD patients, 35 MCI patients who developed AD during longitudinal follow-up, and 341 normal control subjects from the Mayo Clinic Alzheimer's Disease Patient Registry were studied. All participants were typed for apo E using polymerase chain reaction-based assay, epsilon 4+ and epsilon 4- groups were compared on cognitive factor scores of Verbal Comprehension, Perceptual Organization, Attention/Concentration, Learning, and Retention. Raw delayed verbal recall and visual confrontation naming scores supplemented these scores. Multivariate ANOVA was completed for cognitive scores. As expected, a main effect for diagnostic group was present across all scores. Multivariate main effects for age group and apo E genotype were also statistically significant. Subsequent within-group comparisons revealed no genotype differences for control subjects across all cognitive scores except raw delayed recall where an interaction indicated that older epsilon 4+ control subjects actually scored better than younger epsilon 4+ patients. Genotype differences were present for the Retention factor in the MCI sample and for Verbal Comprehension and Learning in the AD sample. In a combined cognitive impairment sample (AD + MCI), genotype differences were present for Verbal Comprehension, Learning, and Retention. Possession of an apo E epsilon 4 allele did not appear to be associated with poorer cognitive performance among normal control subjects. In the AD and MCI samples, epsilon 4+ status was associated with greater memory impairment in analyses including duration of illness as a covariate. In combined AD + MCI analyses, epsilon 4 homozygosity was associated with poorer retention, learning, and verbal comprehension at a given disease duration. Possession of the epsilon 4 genotype may influence cognition in a dose-response relationship.

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PubMed1998

REM sleep behavior disorder and degenerative dementia: an association likely reflecting Lewy body disease.

BACKGROUND: REM sleep behavior disorder (RBD) has been reported with various neurodegenerative disorders, most frequently in disorders with Lewy body pathology. RBD often precedes the onset of PD, and a recent prospective study showed that 38% of patients with RBD eventually developed PD. METHODS: We identified 37 patients with degenerative dementia and a history of bursts of vigorous movement of the arms and legs with vocalization during sleep and associated with dream recall. Patients with and without two or more signs of parkinsonism were compared. Clinical, laboratory, and neuropsychometric features were analyzed, and criteria for the clinical diagnosis of dementia with Lewy bodies (DLB) were applied to all patients. RESULTS: Thirty-four of the 37 patients were male with mean age at onset of 61.5 years for RBD and 68.1 years for cognitive decline. RBD commenced before or concurrently with dementia in all patients but two. Parkinsonism (two or more signs) occurred in 54% of the sample (20/37), with a mean age at onset of 69.1 years. Polysomnography (PSG) confirmed RBD in all patients studied. Neuropsychological testing demonstrated impaired perceptual-organizational skills, verbal fluency, and marked constructional dyspraxia in more than one-half the patients. There were no statistically significant differences in the frequency of clinical features or in neuropsychological performance between patients with and without parkinsonism. Thirty-four patients (92%) met criteria for clinically possible or probable DLB. Three patients were autopsied; all had limbic with or without neocortical Lewy bodies. CONCLUSIONS: We report a group of predominantly male patients with a characteristic association of RBD and degenerative dementia. The clinical and neuropsychometric features of the groups of patients with and without parkinsonism are similar. We hypothesize that the underlying pathology in these patients is DLB.

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PubMed1998

Rate of medial temporal lobe atrophy in typical aging and Alzheimer's disease.

OBJECTIVES: To determine the annual rates of volumetric change of the hippocampus and temporal horn in cognitively normal elderly control subjects and individually matched patients with AD, and to test the hypothesis that these rates were different. BACKGROUND: Cross-sectional studies consistently reveal cerebral atrophy in elderly nondemented subjects compared with healthy young adults, and greater atrophy in patients with AD relative to elderly control subjects. However, rates of atrophy are estimated most accurately by performing serial measurements in the same individuals. METHODS: MRI-based volumetric measurements of the hippocampi and temporal horns were performed in 24 cognitively normal subjects aged 70 to 89 years who were individually matched with respect to gender and age with 24 patients with AD. Each subject underwent an MRI protocol twice, separated by 12 months or more. RESULTS: The mean annual rate of hippocampal volume loss among control subjects was -1.55+/-1.38% and the temporal horns increased in volume by 6.15+/-7.69% per year. These rates were significantly greater among AD patients: hippocampus, -3.98+/-1.92% per year, p < 0.001; temporal horn, 14.16+/-8.47% per year, p = 0.002. CONCLUSION: A statistically significant yearly decline in hippocampal volume and an increase in temporal horn volume was identified in elderly control subjects who represent typical aging individuals. These rates were approximately 2.5 times greater in patients with AD than in individually age- and gender-matched control subjects.

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PubMed1998

Transthyretin amyloidosis (serine 44) with headache, hearing loss, and peripheral neuropathy.

A 32-year-old man of Irish descent presented with severe progressive headache and sensorineural hearing loss. MRI/magnetic resonance angiography head scans were normal. A length-dependent sensorimotor peripheral neuropathy with autonomic dysfunction predated these symptoms. Systemic organ involvement and transthyretin (TTR) amyloid immunostaining of bone marrow and fat aspirate were documented. Direct DNA sequencing revealed both the normal TTT (phenylalanine) and a new variant TCT (serine) at position 44 of the TTR gene. This case expands the genotypic and phenotypic variability within TTR amyloidosis.

Adult↗

PubMed1998

Olfactory dysfunction in Guamanian ALS, parkinsonism, and dementia.

OBJECTIVES: To assess whether olfactory deficits are present in the general Guamanian Chamorro population and to evaluate olfaction in each of the four neurodegenerative disease syndromes of Guam: ALS, pure parkinsonism, pure dementia, and the combined parkinsonism-dementia complex (PDC). BACKGROUND: Olfactory dysfunction was previously reported in patients with PDC of Guam. METHODS: We developed a culturally adjusted olfactory test battery, derived from the original University of Pennsylvania Smell Identification Test (UPSIT), and administered this to Chamorro residents with ALS (n=9), pure parkinsonism (n=9), pure dementia (n=11), PDC (n=31), and 53 neurologically normal Chamorro and 25 North American control subjects. RESULTS: Similar, marked olfactory dysfunction was found in all four syndromes of Guamanian neurodegenerative disease. This correlated poorly with measures of parkinsonism and cognition. In the neurologically normal Chamorro control group, six subjects (11%) had very low olfactory scores; these were less than the lowest North American score, raising a question of subclinical neurodegenerative disease. CONCLUSIONS: Marked olfactory deficits are common to all four Guamanian neurodegenerative syndromes, and suggest the possibility of similar central neuropathologic substrates. The deficit in the Guamanian ALS group contrasts with idiopathic ALS, in which olfactory function has been reported to be only slightly compromised.

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PubMed1997

Guamanian neurodegenerative disease: ultrastructural studies of skin.

It is evident that Guamanian amyotrophic lateral sclerosis (ALS) and parkinsonism-dementia complex (PDC) are clinical variants of a single disease entity and that Guamanian ALS is clinically indistinguishable from sporadic ALS. We studied by electron microscopy the skin tissues from 11 patients with Guamanian neurodegenerative disease (PDC and ALS), 11 Chamorro control subjects, 10 Japanese patients with sporadic ALS and 11 Japanese control patients. Among patients with sporadic ALS, there was an inverse relationship of collagen fiber diameter and the duration of disease and a marked increase of amorphous material in the ground substance. These findings were not observed in the Guamanian patients or controls. Therefore, the skin studies reinforce the view of a different disease mechanism in Guamanian ALS and PDC compared to sporadic ALS.

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PubMed1997

Neuronal loss correlates with but exceeds neurofibrillary tangles in Alzheimer's disease.

To assess the relationship between dementia, neuronal loss, and neuropathological findings in Alzheimer's disease (AD), we counted the number of neurons, senile plaques, and neurofibrillary tangles in a high-order association cortex. We studied the superior temporal sulcus of 34 individuals with AD and 17 nondemented control subjects, using statistically unbiased, stereological counting techniques. The number of superior temporal sulcus neurons in nondemented control subjects was stable across the sixth to ninth decades. In AD, more than 50% of the neurons were lost. Both neuronal loss and neurofibrillary tangles increased in parallel with the duration and severity of illness, but the amount of neuronal loss exceeded by manyfold the amount of neurofibrillary tangles accumulated. In contrast to the correlation between neurofibrillary tangles and neuronal loss, the number of senile plaques and the percentage of the superior temporal sulcus that was covered by Abeta (amyloid burden) were not related to neuronal loss, number of neurofibrillary tangles, or duration of disease. Neither the amount nor the rate of neuronal loss in the superior temporal sulcus in AD correlated with apolipoprotein E genotype. These data suggest that neuronal loss in association areas such as the superior temporal sulcus contributes directly to cognitive impairment in AD.

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PubMed1997

Aging, memory, and mild cognitive impairment.

In recent years, patients who are at high risk for developing Alzheimer's disease (AD) have become a focus of study. Several research groups have identified these patients, developed diagnostic criteria, and followed the patients longitudinally. These patients therefore constitute a clinical entity that is suitable for therapeutic interventions. In this article, we report our 5-year experience at the Mayo Clinic in characterizing a group of patients with mild cognitive impairment. These subjects were recruited from community-dwelling individuals who were receiving general medical care in the Department of Internal Medicine. They received the diagnosis of mild cognitive impairment if they met the following criteria: (a) complaint of defective memory, (b) normal activities of daily living, (c) normal general cognitive function, (d) abnormal memory function for age, and (e) absence of dementia. In following more than 75 of these patients, some of whom have been studied for as long as 5 years, it appears that approximately 10% to 15% of the subjects evolve to AD each year. We therefore evaluated the cognitive profiles of these patients at the time of their initial diagnosis in an attempt to predict who would remain stable and who would evolve to AD. Certain features of learning and memory performance indicated patients who were more likely to progress, but the strongest predictor was their apolipoprotein E status. The patients who possessed an epsilon 4 allele were more likely to convert to AD at a more rapid rate then those who were not carriers. Our results and similar data from other study groups indicate that diagnostic criteria can be defined for patients who are likely to convert to AD; the natural history of these patients is becoming apparent, and variables that predict ultimate conversion can be defined. Consequently, patients with mild cognitive impairment constitute an important group for study, particularly form the aspect of therapeutic interventions.

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PubMed1997

Free and cued selective reminding test: MOANS norms.

Age-adjusted norms are presented for persons age 56-98 years on the Free and Cued Selective Reminding Test (FCSRT; Buschke, 1984; Grober & Buschke, 1987). These data were obtained via several research projects that are known collectively as Mayo's Older Americans Normative Studies (MOANS). These norms should be useful when the FCSRT is used as a "stand alone" test. They should also promote accuracy in the comparison of any person's FCSRT performance against his or her functioning on any other tests with MOANS norms. The unique features of the FCSRT are discussed. These norms will, hopefully, enhance the utility of the test when it is used in clinical and research investigations of various amnestic disorders.

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PubMed1997

Hippocampal transverse relaxation times in patients with Alzheimer disease.

PURPOSE: To determine whether hippocampal relaxation times in magnetic resonance (MR) imaging differ between patients with probable Alzheimer disease and elderly control subjects with normal cognition. MATERIALS AND METHODS: MR imaging relaxation times were measured in the head and body of the right and left hippocampi in 123 subjects: 62 patients with Alzheimer disease (44 women, 18 men; age range, 65-89 years) and 61 elderly control subjects without cognitive impairment (39 women, 22 men; age range, 65-89 years). Hippocampal relaxation times were correlated with clinical status (patient vs control subject), age, sex, laterality (right vs left), and location within the hippocampus (body vs head). The hippocampal T2 value was correlated with the severity of disease in the patients. RESULTS: No statistically significant difference in the relaxation times was found between the two clinical groups for the analysis of the right versus left hippocampi and the hippocampal head versus body. In both patients and control subjects, no correlation was found between T2 measurements and age or sex. Twenty-seven patients had a clinical dementia rating (CDR) score of 0.5 (very mild dementia), 21 patients had a CDR score of 1.0 (mild dementia), and eight patients had a CDR score of 2.0 (moderate dementia). The CDR score was not available in six patients. No statistically significant association between T2 values and severity of disease was observed. CONCLUSION: MR relaxation time measurements in the hippocampus are not useful for the detection of Alzheimer disease.

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PubMed1997

Guamanian neurodegenerative disease: are diabetes mellitus and altered humoral immunity clues to pathogenesis?

On the western Pacific island of Guam, parkinsonism, dementia, and amyotrophic lateral sclerosis are highly prevalent but the cause is not known. To assess the possibility that the pathologic process extends beyond the nervous system, we studied patients with Guamanian neurodegenerative disease (N = 16) and Guamanian Chamorro control subjects (N = 16) in the Clinical Research Center of the Mayo Clinic, Rochester, MN. The principal abnormalities found in those with neurodegenerative disease included diabetes mellitus in 44%, elevated levels of serum immunoglobulin A (IgA) in 50%, and elevated IgG in 44%. The mean serum IgM level in the patient group was significantly lower than in the control group. Diabetes mellitus and elevated IgA and IgG levels were also present in 31% of neurologically normal Guamanian subjects. Some of these control subjects, however, probably have preclinical neurodegenerative disease, as found in previously published postmortem studies. Extensive serologic testing did not reveal any consistent profile of autoimmunity. Other blood and urine studies failed to identify hematologic, nutritional, renal, hepatic, or metabolic abnormalities that distinguished patients. Whether diabetes mellitus or abnormalities of immune regulation share common etiopathology with Guamanian neurodegenerative disease deserves further study.

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PubMed1997

Medial temporal atrophy on MRI in normal aging and very mild Alzheimer's disease.

Magnetic resonance imaging (MRI)-based volumetric measurements of medial temporal lobe (MTL) structures can discriminate between normal elderly control subjects and patients with Alzheimer's disease (AD) of moderate to advanced severity. In terms of clinical utility, however, a more important issue concerns the ability of the technique to differentiate between normal elderly control subjects and AD patients with the very mildest form of the disease. We performed MRI-based volumetric measurements of the hippocampus, parahippocampal gyrus, and amygdala in 126 cognitively normal elderly control subjects and 94 patients with probable AD. The diagnosis of AD was made according to NINDS/ADRDA criteria, and disease severity was categorized by Clinical Dementia Rating (CDR) scores. Patients with CDR 0.5 were classified as very mild, CDR 1 as mild, and CDR 2 as moderate disease severity. Volumes of each structure declined with increasing age in control subjects and did so in parallel for men and women. The volume of each measured MTL structure also declined with age in patients with AD. The volume of each MTL structure was significantly smaller in AD patients than control subjects (p < 0.001). Of the several MTL measures, the total hippocampal volumetric measurements were best at discriminating control subjects from AD patients. The mean hippocampal volumes for AD patients relative to control subjects by severity of disease were as follows: very mild AD (CDR 0.5) -1.75 SD below the control mean, mild AD (CDR 1) -1.99 SD, and moderate AD (CDR 2) -2.22 SD. Age- and gender-adjusted, normalized MRI-based hippocampal volumetric measurements provide a sensitive marker of the MTL neuroanatomic degeneration in AD early in the disease process.

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