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Biomedical subjects

A S Buchman

Publications and source records attributed to A S Buchman.

17 recordsLinked to original sources
PubMed2007

Physical activity and motor decline in older persons.

We tested the hypothesis that physical activity modifies the course of age-related motor decline. More than 850 older participants of the Rush Memory and Aging Project underwent baseline assessment of physical activity and annual motor testing for up to 8 years. Nine strength measures and nine motor performance measures were summarized into composite measures of motor function. In generalized estimating equation models, global motor function declined during follow-up (estimate, -0.072; SE, 0.008; P < 0.001). Each additional hour of physical activity at baseline was associated with about a 5% decrease in the rate of global motor function decline (estimate, 0.004; SE, 0.001; P = 0.007). Secondary analyses suggested that the association of physical activity with motor decline was mostly due to the effect of physical activity on the rate of motor performance decline. Thus, higher levels of physical activity are associated with a slower rate of motor decline in older persons.

Activities of Daily Living↗
PubMed2006

Body mass index in older persons is associated with Alzheimer disease pathology.

OBJECTIVE: We examined the extent to which body mass index (BMI) in older persons is associated with common age-related neuropathologies known to contribute to dementia including Alzheimer disease (AD) pathology, cerebral infarction, and Lewy body disease. METHODS: We studied brain autopsies from 298 deceased Catholic clergy participating in the Religious Orders Study, a longitudinal clinical-pathologic investigation. BMI was assessed at annual clinical evaluations during an average follow-up of 4.9 years (SD = 2.7 years). Each person's average BMI, derived from all evaluations, was used in analyses. Multiple regression analyses were used to examine the relation of common postmortem neuropathologic findings to average BMI prior to death. RESULTS: Mean age at death was 85.7 years (SD = 6.8 years), and average BMI during the course of the study was 26.0 (SD = 5.1). A series of linear regression models was performed with average BMI as the outcome and controlling for age, sex, and education. Level of AD pathology was associated with BMI proximate to death (estimate = -1.15; SE = 0.42; p = 0.007). However, Lewy body pathology (estimate = -0.45; SE = 0.73; p = 0.53) and cerebral infarctions (estimate = -0.10; SE = 0.61; p = 0.88) were not associated with average BMI. The association of AD pathology with BMI was unchanged after controlling for dementia, chronic diseases, and physical activity. CONCLUSION: Body mass in old age is associated with Alzheimer disease pathology in persons with and without dementia.

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PubMed2005

Change in body mass index and risk of incident Alzheimer disease.

OBJECTIVE: To examine the association of change in body mass index (BMI) with risk of Alzheimer disease (AD). METHODS: Nine hundred eighteen older Catholic clergy participating in the Religious Orders Study without dementia at baseline were studied. Outcome measures were the clinical diagnosis of AD and change in cognitive function. RESULTS: During a mean follow-up of 5.5 years, 151 persons developed AD. BMI averaged 27.4 at baseline and declined in about half the participants. In a proportional hazards model adjusted for age, sex, and education, each 1-unit less of BMI at baseline was associated with about a 5% increase in the risk of AD (hazard ratio = 0.944; 95% CI = 0.908 to 0.981), and each 1-unit annual decline in BMI (about the 10th percentile) was associated with about a 35% increase in the risk of AD compared with a person experiencing no change in BMI (about the 50th percentile) (hazard ratio = 0.730; 95% CI = 0.625 to 0.852). The results were similar after controlling for chronic diseases and excluding persons who developed AD during the first 4 years of observation. Random effects models showed that the rate of cognitive decline increased by about 8% for each 1-unit less of BMI at baseline and declined an additional 40%/year in persons losing 1 unit of BMI/year compared with those with no change in BMI. CONCLUSION: Declining body mass index (BMI) is associated with increased risk of incident Alzheimer disease (AD). Loss of BMI may reflect pathologic processes that contribute to the subsequent development of AD.

Age Factors↗
PubMed2001

Control of movement distance in Parkinson's disease.

Studies of electromyographic (EMG) patterns during movements in Parkinson's disease (PD) have often yielded contradictory results, making it impossible to derive a set of rules to explain how muscles are activated to perform different movement tasks. We sought to clarify the changes in modulation of EMG parameters associated with control of movement distance during fast movements in patients with PD. Specifically, we studied surface EMG activity during rapid elbow flexion movements over a wide range of distances (5-72 degrees) in 14 patients with relatively mild symptoms of PD and 14 control subjects of similar age, sex, height, and weight. The PD group exhibited several changes in EMG modulation including impaired modulation of agonist burst duration; increased number of agonist bursts; reduced scaling of agonist EMG magnitude in the more severely impaired subjects; and increased temporal overlap of the antagonist and agonist signals in the most severely impaired subjects. These findings suggest that progressive motor dysfunction in PD is accompanied by increasing deficits in modulating muscle activation. These results help clarify previous disparate and sometimes contradictory results of EMG patterns in subjects with PD.

Adult↗
PubMed2000

Effect of age and gender in the control of elbow flexion movements.

In previous studies of rapid elbow movements in young healthy men, characteristic task-dependent changes in the patterns of muscle activation when movement speed or distance was varied have been reported. In the present study, the authors investigated whether age or gender is associated with changes in the patterns of muscle activity previously reported in young men. Arm movements of 10 healthy older and 10 healthy younger participants (5 men and 5 women in each group) were studied. Surface electromyograms (EMGs) from agonist (biceps) and antagonist (triceps) muscles, kinematic and kinetic parameters, as well as anthropometric and strength measures were recorded. All 4 groups of participants showed similar task- (distance or speed) dependent changes in biphasic EMG activity. Similar modulation of the initial rate of rise of the EMG, integrated agonist and antagonist EMG activity, as well as their relative timing were observed in all 4 groups. Those results suggest that older individuals of both genders retain the control strategies for elbow movements used by young individuals. Despite the qualitative similarities in the patterns of muscle activation, the men moved more quickly than the women, and younger participants moved more quickly than older participants. Those performance differences could not be explained in terms of differences in body size and strength alone.

Adult↗
PubMed1998

The effect of changes in head posture on the patterns of muscle activity in cervical dystonia (CD).

Twelve patients with cervical dystonia (CD) and predominant rotation were studied to determine the effects of changes in head posture on the specific patterns of cervical muscle activity. Turns analysis was used to quantify muscle activity underlying head rotation, recorded simultaneously from the agonist and antagonist muscle pairs bilaterally (sternocleidomastoid [SCM] and splenius [SPL]). Muscle activity was compared between the uncompensated dystonic posture and during the maintenance of midposition. In addition, patients were separated into two groups (geste = 6; no geste = 6) based on whether they had a clinically efficacious geste to determine the effect of geste on patterns of cervical muscle activity. Muscle activity was measured during the maintenance of midposition with and without a clinical or simulated geste. Differences in muscle activity between the groups and postures were compared using repeated measure analysis of variance (ANOVA) analyses. The four muscles tested showed a significant difference in muscle activity in the uncompensated dystonic posture as a result of the increased activity in the agonist muscle pair (SCM and SPL responsible for the dystonic posture) (EMG amplitude: F[1,11] = 18.81, p = 0.0012; EMG frequency: F[1,11] = 32.07, p = 0.0001). Maintaining the head in the midposition was associated with a significant reduction in muscle activity compared with the uncompensated dystonic posture (EMG amplitude: F[1,9] = 6.36, p < 0.033; EMG frequency: F[1,9] = 10.96, p < 0.0091). This reduction in midposition muscle activity was significantly greater in the agonist muscle pair (EMG amplitude: F[1,10] = 19.70, p = 0.0013; EMG frequency: F[1,10] = 44.67, p < 0.0001). In the patients with clinically effective geste, there was no additional reduction in muscle activity observed in the midposition when they performed their geste (EMG amplitude: F[1,9] = 4.63, p = 0.060; EMG frequency: F[1,9] = 1.22, p = 0.298). These findings suggest that CD with rotation is characterized by predominantly increased agonist muscle activation. Patients with CD retain the ability to modulate this involuntary agonist muscle activity to maintain the head in the midposition. The maintenance of the midposition does not seem to be facilitated by geste.

Adult↗
PubMed1993

Quantitative electromyographic analysis of changes in muscle activity following botulinum toxin therapy for cervical dystonia.

Reports of efficacy of botulinum toxin for cervical dystonia have relied on subjective reports of improvement or various clinical rating scales. We studied 19 patients with cervical dystonia using Turns analysis to determine if quantitative EMG measures of muscle activity changed following botulinum toxin injections. Before and after botulinum toxin injections, six muscles were evaluated bilaterally. Quantitative EMG analysis of active muscles injected with botulinum toxin showed a significant decline in muscle activity after botulinum toxin (F = [1,41] 55.0; p < 0.001). Significant reductions in quantitative EMG parameters were also noted in noninjected active muscles after botulinum toxin treatment (F = [1,51] 59.15; p < 0.001). The sum of EMG activity for all active muscles was calculated for each subject and showed a significant reduction after botulinum toxin injection [MANOVA: (F = [1,5] 5.69; p < 0.05]. Quantitative EMG assessment provides an objective measure of response to botulinum toxin. Decreased muscle activity in noninjected muscles may result from toxin diffusion or reflect relaxation of muscles only secondarily involved in cervical dystonia.

Adult↗
PubMed1992

Determining neuromuscular jitter using a monopolar electrode.

Neuromuscular jitter was determined in the extensor digitorum communis (EDC) of 41 healthy control subjects and 8 patients with myasthenia gravis (MG). Standard single-fiber electromyographic (SFEMG) techniques were used, except that a monopolar electrode (MPE) was substituted for a single-fiber electrode (SFE). In normals, mean jitter for 20 pairs was 22.4 +/- 2.8 microseconds and the mean jitter for an individual pair was 22 +/- 5.6 microseconds. In the age range tested (18 to 49 years), jitter did not change with increasing age. When MPE jitter studies were repeated in 16 normals, mean jitter usually varied by less than 10% (mean 7.4% +/- 6.2%) and remained normal. Jitter was significantly increased in MG compared to normals 73 +/- 56 microseconds versus 22 +/- 5.6 microseconds (F = 149.4, P less than 0.0001). Using an analog pain scale, the discomfort during electromyography using MPE and SFE was compared between the left and right arms in 35 normals. MPEs caused less discomfort than SFEs (P = 0.0031), and were preferred (71% versus 20%) to SFEs (chi 2 = 9.21, P = 0.01). Based on these results, we conclude that MPE determined jitter studies are reproducible, can distinguish between normals and MG, and are associated with less discomfort than SFE.

Adult↗
PubMed1992

Botulinum toxin injection for spasmodic torticollis: increased magnitude of benefit with electromyographic assistance.

To determine the usefulness of EMG-assisted botulinum toxin (BOTOX) injections for the treatment of spasmodic torticollis (ST), we randomized 52 ST patients into two groups and studied them prospectively. In one group [(E+C)RX, N = 28], the muscles were selected for BOTOX injection using both clinical and EMG examination and then injected with EMG assistance. In the second group [(C)RX, N = 24] the muscles were selected for BOTOX injection based solely on clinical examination and injected without EMG assistance. The percentage of patients showing any improvement after BOTOX as similar in both the (E+C)RX and (C)RX groups. A significantly greater magnitude of improvement was present in the (E+C)RX group, as well as a significantly greater number of patients with marked improvement. In particular, patients with retrocollis, head tilt, and shoulder elevation demonstrated additional benefit with EMG-assisted BOTOX injection. EMG assistance may be effective because the technique increases the ability to effectively identify and treat the deep cervical muscles.

Adult↗
PubMed1988

Risk factors for progression in Parkinson's disease.

Using case-control methodology, we assessed prevalence and duration of exposure to putative risk factors for rapid progression of Parkinson's disease (PD) in patients not taking levodopa or direct dopamine agonists. We identified 31 patients termed "rapidly progressive" who were stage I or II (Hoehn and Yahr) on their first visit to our center and who progressed to stage III during the study period; we pair-matched this group with 31 "slowly progressive" patients who had the same symptom duration and the same Hoehn and Yahr stage at study entry, but whose parkinsonism did not progress to stage III during the study. Only age of PD onset was associated with different rates of PD progression; older patients at PD onset progressed more rapidly than younger patients.

Age Factors↗
PubMed1988

Hemiparkinsonism with hemiatrophy.

We studied fifteen patients with hemiparkinsonism and ipsilateral hemiatrophy (HP/HA) to better characterize the clinical features of this syndrome and its rate of progression. Patients were distinguished by highly asymmetric parkinsonism with predominant signs on the side of HA, early age of onset (43.7 years versus 60.2 years in our control population of idiopathic Parkinson's disease [IPD], abnormal birth history (7/15), and dystonia occurring prior to levodopa therapy (10/15). In six patients, the mean duration of disease until the initiation of levodopa therapy was 14.2 years, as compared with 4.1 years in our control population of IPD. The slow progression of disease underscores the relatively favorable prognostic significance of HP/HA and its distinction from IPD.

Adult↗
PubMed1986

Word deafness: one hundred years later.

Since its original description the diagnosis of word deafness has been greatly expanded. Confusion has arisen with regard to the usage of the related terms pure word deafness, auditory agnosia, and cortical deafness. Three new cases of word deafness are presented including one case with CT and necropsy correlation. These cases are compared with 34 previously reported cases of various cortical auditory disorders. Our review establishes that patients with word deafness who have had formal testing of linguistic and non-linguistic sound comprehension and musical abilities always demonstrated a more pervasive auditory agnosia. Despite the spectrum of auditory deficits and associated language abnormalities, patients with word deafness share common features including aetiology, pathology, clinical presentation and course. These common features justify inclusion of heterogeneous cortical auditory disorders under the rubric of word deafness. Despite some limitations the term "word deafness" should be retained for this syndrome, since inability to comprehend spoken words is the most distinctive clinical deficit. Word deafness is most frequently caused by cerebrovascular accidents of presumed cardiac embolisation, with bitemporal cortico-subcortical lesions. The sequence of cerebral injury is not predictive of resulting auditory deficits. Impairment of musical abilities parallels the severity of the auditory disorder.

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